geology of a major new porphyry copper center in the superior pioneer district arizona a new porphyry copper deposit has been discovered in the superior pioneer district of east central arizona lying under thick tertiary cover approximately 2 km south of the historic magma vein the porphyry center was encountered in the course of an exploration drilling campaign conducted from 1992 through 1997 comprising a series of subvertical surface core holes and subhorizontal underground core holes ranging in length from 1 000 to 1 955 m the system is large structurally intact and shows indications of a substantial hypogene mineralized zone that averages between 1 0 and 2 0 percent cu the deposit is hosted by a thick sequence of cretaceous volcaniclastic and siliciclastic sedimentary rocks the mesozoic strata rest disconformably on calcareous units of the uppermost paleozoic naco group and are intruded by an east northeast striking swarm of quartz porphyry dikes the dike swarm is truncated at the basal tertiary unconformity under which the mesozoic section is buried by 600 to 1 200 m of unmineralized overburden composed of the oligocene miocene whitetail conglomerate and the miocene 18 6 ma apache leap dacite tuff the attitude of the basal tertiary beds shows that the porphyry center has been tilted 30 to 35 to the east northeast a broad zone of hydrolytic alteration characterizes the high structural levels in mesozoic wall rocks peripheral propylitic alteration in the volcaniclastic rocks is marked by epidote and chlorite giving way inwardly to a narrow zone of chlorite dominant alteration in which epidote is destabilized in favor of smectite clays and carbonate this chlorite zone corresponds closely to the intermediate argillic alteration type of meyer and hemley 1967 the propylitic fringe of the system is erratically mineralized by vein controlled pyrite sphalerite and specularite with minor chalcopyrite and galena chloritic rocks in the intermediate argillic halo contain pyrite and chalcopyrite the intermediate argillic alteration mantles an inner zone of pervasive quartz sericite pyrite the sericitic zone is strongly pyritic with bornite and lesser chalcopyrite within sericitically altered rock pyrite chalcocite digenite bornite veins exhibit centimeters to meters wide halos of advanced argillic alteration in which sericite is replaced by kaolin group clays the quartz sericite pyrite zone is superimposed on earlier potassic alteration that remains preserved at deeper levels the base of the mesozoic sequence and shaly beds in the upper naco group section are pervaded with secondary biotite calcareous rocks in the naco group are altered to 1 pyroxene epidote hornfelses and minor garnet magnetite skarn overprinted by 2 actinolite and 3 chlorite carbonate clay alteration biotitically altered rocks are mineralized by quartz pyrite chalcopyrite anhydrite veins molybdenite is present in an early generation of quartz rich pyrite chalcopyrite veins hornfelses and skarn in the naco group are strongly mineralized by quartz poor chalcopyrite pyrite anhydrite veins with chloritic envelopes surface and underground drilling into the deposit has outlined a zone of 1 0 percent hypogene cu that is at least 750 m long by 250 m wide by 300 m high elongated to the east northeast the same volume of rock also averages 0 02 percent mo and 2 ppm ag this zone apexes approximately 300 m below sea level slightly more than 1 5 km below the ground surface and remains open in all directions laterally and at depth four of the last five drill holes penetrating this zone ended in rock assaying 2 0 percent hypogene cu

application of thermochronology to hydrothermal ore deposits thermochronology finds many applications in economic geology utilizing temperature sensitive radiometric dating techniques to reveal low temperature upper crustal processes can elucidate many aspects of deposit genesis including timing and duration of mineralization processes rate of exhumation and erosion of intrusive ore deposits and comparative preservation potential the tools are utilized to best advantage when combined with other thermochronometry techniques that provide complementary information in addition when thermochronometers are combined with geochronometers e g zircon u pb over 800 c of thermal history is revealed from emplacement to erosion fig 1 with the advent of computational algorithms that provide more accurate and detailed models of thermochronology results the economic geologist has a powerful tool to use when assessing economic favorability of a region or prospect this chapter summarizes the various ways that low temperature thermochronometers have been utilized in studies of economic mineralization and primarily focuses on studies of porphyry ore deposits these deposits are well characterized and provide a good platform from which to demonstrate the extended understanding of ore formation processes that is provided by thermochronology studies in this section we review the fundamental application of u th he fission track and 40ar 39ar thermochronometry methods to mineralized systems we then present a synopsis of how these techniques can be used in thermal history analysis either alone or in combination with other chronometers in order to provide more information on deposit genesis the discussion is presented from low through to higher temperature thermochronometers corresponding to their presentation on figure 1 u th he thermochronology as documented earlier in the volume u th he thermochronology is based on measuring the accumulation of radiogenic 4he produced from u and th decay the daughter helium is retained until the mineral is heated to a temperature at which its structure and helium retentivity change this closure temperature varies from

factors controlling geochemical and mineralogical compositions of coals preserved within marine carbonate successions a case study from the heshan coalfield southern china abstract the late permian coals in the heshan coalfield of southern china are preserved within marine carbonate successions and characterized by super high organic sulfur 5 13 10 82 minerals identified in the coals include quartz kaolinite illite mixed layer illite smectite albite pyrite marcasite calcite and dolomite along with trace amounts of smectite fluorite strontianite rey bearing carbonate minerals jarosite and water bearing fe oxysulfate the coals are very rich in trace elements including f up to 3362 g g v up to 270 g g se up to 24 4 g g mo up to 142 g g u up to 111 g g and to a lesser extent sr y zr nb cd cs heavy rare earth elements hf ta w hg and th previous studies attributed the high organic sulfur and elevated trace elements to the seawater influence or the formation of soil horizons before the accumulation of peat in the basin however mineralogical and geochemical data presented in this study have shown that the sediment source region and multi stage hydrothermal fluids are the dominant influences on the mineralogical composition and elevated trace elements in the coal although seawater influence also contributed to the composition of the mineral matter for example a large proportion of the quartz and clay minerals as well as almost all the albite in both the coal benches and the parting mudstones were derived from detrital materials of terrigenous origin in the yunkai upland high concentrations of lithophile trace elements were also derived from the sediment source region minerals including fluorite calcite dolomite strontianite and rey bearing carbonate minerals were derived from multi stage hydrothermal activities high concentrations of v mo and u that occur through the coal seam sections were probably derived from hydrothermal solutions during peat accumulation or at the early diagenetic stages the hydrothermal fluids also corroded the syngenetically formed minerals quartz albite and pyrite and caused re distribution of lithophile elements from partings to the underlying coal benches resulting in higher key element ratios yb la nb ta and zr hf and more abundant heavy rare earth elements in the coal benches than in the immediately overlying partings

petrographic and geochemical contrasts and environmentally significant trace elements in marine influenced coal seams yanzhou mining area china abstract the yanzhou mining area in west shandong province china contains coals of permian and carboniferous age the 31 and 32 seams of the permian shanxi formation and seams 6 15 17 of the carboniferous taiyuan formation were analyzed for coal petrology mineralogy and geochemical parameters the parameters indicate that the coal is high volatile bituminous in rank the coal is characterized by high vitrinite and low to medium inertinite and liptinite contents these properties may be related to evolution of the coal forming environment from more reducing conditions in a marine influenced lower delta plain environment for the early taiyuan coals to more oxidizing paleoenvironments in an upper delta plain for the upper shanxi coal seams the major mineral phases present in the coal are quartz kaolinite pyrite and calcite sulfur is one of the hazardous elements in coal the major forms of sulfur in coal are pyritic organic and sulfate sulfur pyritic and organic sulfur generally account for the bulk of the sulfur in coal elemental sulfur also occurs in coal but only in trace to minor amounts in this paper the distribution and concentration of sulfur in the yanzhou mining district are analyzed and the forms of sulfur are studied the sulfur content of the taiyuan coal seams is considerably higher than that of the shanxi coals organic sulfur content is positively correlated to total and pyritic sulfur the vertical variation of cu zn pb as th u and sulfur contents in coal seam 3 of the shanxi formation in the xinglongzhuang mine show that all these trace elements with the exception of th are enriched in the top and bottom plies of the seam and that their concentrations are also relatively high in the dirt bands within the seam the pyritic sulfur is positively correlated with total sulfur and both are enriched in the top bottom and parting plies of the seam the concentrations of the trace elements are closely related to sulfur and ash contents most of the trace elements are correlated with the ash content and may be associated with the mineral matter in the coal

origin of minerals and elements in the late permian coals tonsteins and host rocks of the xinde mine xuanwei eastern yunnan china abstract this paper reports the mineralogical and geochemical compositions of the late permian c2 and c3 coals both medium volatile bituminous coal from the xinde mine near xuanwei in eastern yunnan which is located close to the area with the highest female lung cancer mortality in china the two coals are characterized by high ash yields and low sulfur contents three factors including sediment source region multi stage volcanic ash generation and multi stage hydrothermal fluid injections were responsible for variations in the geochemical and mineralogical compositions of the xinde coals trace elements including v sc co ni cu zn se zr nb hf and ta are enriched in the coals and were mainly derived from the sediment source kangdian upland region major minerals in the samples of coal roof floor and non coal sediment partings include quartz kaolinite and chamosite as well as interstratified illite smectite and anatase chamosite in the coal was derived from reactions between kaolinite and fe mg rich hydrothermal fluids however chamosite in the roof strata was directly precipitated from fe mg rich hydrothermal fluids or was derived from the alteration of precursor minerals e g biotite by hydrothermal fluids quartz in some samples is very high especially in the roof strata of the c2 and c3 coal such high quartz along with minor minerals including pyrite chalcopyrite sphalerite calcite celestite vanadinite barite clausthalite and silicorhabdophane were derived from multi stage hydrothermal fluids the floors of both the c2 and c3 coal seams are fully argillized fine grained tuffaceous claystone and the immediate roof of the c2 coal is argillized coarse grained tuff the original materials of the floors and roofs of these coal seams were high ti alkali basaltic volcanic ashes as indicated by high tio 2 nb and siderophile elements and the distribution patterns of rare earth elements two intra seam tonstein layers in the c3 coal were identified based on their lateral persistence mineralogical mode of occurrence and composition as well as their elemental composition the tonsteins are dominated by kaolinite with minor quartz and possibly mixed layer illite smectite both tonsteins were derived from dacitic magma the ratios of nb ta zr hf and u th are much lower in tonsteins than in the adjacent coal benches which is attributed to the hydrothermal leaching

fluid chemistry structural setting and emplacement history of the rosario cu mo porphyry and cu ag au epithermal veins collahuasi district northern chile the rosario cu mo ag deposit is located in the collahuasi district of northern chile it comprises high grade cu ag au epithermal veins superimposed on the core of a porphyry cu mo orebody rosario has mining reserves of 1 094 million metric tons mt at 1 03 percent copper an additional 1 022 mt at 0 93 percent copper occurs in the district at the nearby ujina and quebrada blanca porphyry deposits the rosario reserve contains over 95 percent hypogene ore whereas supergene sulfide ores dominate at ujina and quebrada blanca mineralized veins are hosted within lower permian volcanic and sedimentary rocks lower triassic granodiorite and late eocene porphyritic quartz monzonite the rosario fault system a series of moderate southwest dipping faults has localized high grade cu ag au veins at cerro la grande similar high grade cu ag au veins are hosted in north northeast trending sinistral wrench faults normal movement in the rosario fault system is interpreted to have been synchronous with sinistral strike slip deformation at la grande hydrothermal alteration at rosario is characterized by a k feldspar core focused in the rosario porphyry that grades out to a secondary biotite albite magnetite assemblage paragenetic relationships indicate that magnetite was the earliest formed alteration product but has been replaced by biotite albite vein crosscutting relationships indicate that k feldspar formed during and after biotite albite alteration chalcopyrite and bornite were deposited in quartz veins associated with both k feldspar and biotite albite assemblages the early hydrothermal fluid was a hypersaline brine 40 45 wt nacl that coexisted with vapor between 400 degrees and 600 degrees c weakly mineralized illite chlorite intermediate argillic alteration of the early k and na silicate assemblages was caused by moderate temperature 250 degrees 350 degrees c moderate salinity brines 10 15 wt nacl molybdenite was precipitated in quartz veins that formed between the potassic and intermediate argillic alteration events these fluids were 350 degrees to 400 degrees c with salinities between 10 and 15 wt percent nacl porphyry style ore and alteration minerals were overprinted by structurally controlled quartz alunite pyrite pyrophyllite dickite and muscovite quartz phyllic alteration assemblages the quartz alunite pyrite alteration formed at 300 degrees to 400 degrees c from fluids with a salinity of 10 wt percent nacl the pyrophyllite dickite assemblage formed between 250 degrees and 320 degrees c from dilute 5 wt nacl fluids an upward flared zone of muscovite quartz pyrite altered rocks surrounds the fault controlled domain of advanced argillic alteration thick veins 0 5 2 m wide of fault hosted massive pyrite chalcopyrite and bornite precipitated brines with a salinity of 30 wt percent nacl at temperatures of 250 degrees to 300 degrees c pressure depth estimates indicate that at least 1 km of rock was eroded at rosario between formation of the k na silicate and advanced argillic assemblages this erosion was rapid occurring over a period of 1 8 m y the rosario porphyry intruded immediately after the incaic tectonic phase implying that it was emplaced as the domeyko cordillera underwent gravitational collapse expressed as normal faults in the upper crust gravitational sliding potentially accelerated exhumation and helped to promote telescoping of the high sulfidation environment onto the rosario porphyry the hydrothermal system responsible for porphyry cu mineralization at rosario was partially exhumed prior to the formation of high sulfidation ore and alteration assemblages this implies that emplacement of a second blind intrusion occurred somewhere beneath the rosario and cerro la grande high sulfidation vein systems and is supported by the fault geometry and zoning of precious metals and sulfosalts at the district scale

properties origin and nomenclature of rodlets of the inertinite maceral group in coals of the central appalachian basin u s a abstract resin rodlets sclerenchyma strands and woody splinters which are collectively called rodlets were studied by chemical optical petrographic and scanning electron microscopic sem techniques a study was made of such rodlets from the bituminous coal beds of the central appalachian basin pennsylvanian upper carboniferous of the united states comparisons were made with rodlets from coal beds of the illinois basin the southern anthracite field of pennsylvania the st rose coal field of nova scotia and european and other coal fields in order to determine their physical and chemical properties a detailed study was made of the rodlets from the pomeroy coal bed high volatile a bituminous coal monongahela formation upper pennsylvanian of kanawha county west virginia the origin of the rodlets was determined by a comparative analysis of a medullosan seed fern stem from the herrin no 6 coal bed high volatile c bituminous coal carbondale formation from washington county illinois rodlets are commonly concentrated in fusain or carbominerite layers or lenses in bituminous coal beds of the central appalachian basin most of the rodlets examined in our study were probably derived from medullosan seed ferns the three types of rodlets are distinguished on the basis of cellularity morphology and fracture the resin rodlets studied by us are noncellular and appear to be similar in properties and origin to those found in coal beds of the middle and upper pennsylvanian of the illinois basin the resin rodlets extracted from the pomeroy coal bed exhibit high relief and high reflectance when polished and viewed in reflected light they are opaque in transmitted light in cross section the resin rodlets are oval to round and have diameters ranging from 60 to 450 m many are solid but some have vesicles canals or cavities which are commonly filled with clay probably kaolinite typically they have distinct fracture patterns kerfs in longitudinal and cross sections and many are characterized by dense probably oxidized rims the orientation and amounts of void space and mineralization of resin rodlets in coal have resulted in much confusion in their recognition and classification the resin rodlets are petrographically recognized as sclerotinites of the inertinite maceral group we here propose that resin rodlets be assigned to the maceral variety of sclerotinites termed resino sclerotinite because of their presumable resinous origin other investigators have confused some fusinitized resin rodlets with fungal masses which have different morphological properties and which probably have different chemical properties we here propose that such fungal masses be assigned to the maceral variety of sclerotinites termed fungo sclerotinite the sclerenchyma strands examined in our study are cellular thick walled and crescent shaped in cross section they exhibit high reflectance and high relief and belong to semifusinite and fusinite of the inertinite maceral group sclerenchyma strands are commonly associated with resin canals in medullosa and related seed fern genera which are common in coal balls of the illinois basin we here propose adoption of the maceral varietal terms sclerenchymo fusinite and sclerenchymo semifusinite for these bodies the woody splinters in the pomeroy coal bed are cellular and thin walled and have scattered pits as much as a few microns in diameter they are dark brown to black in transmitted light and commonly have a lower reflectance than the resino sclerotinite and sclerenchymo fusinite of the pomeroy coal the woody splinters belong to semifusinite and fusinite of the inertinite maceral group the maceral varietal terms xylemo semifusinite and xylemo fusinite are here proposed for these bodies elemental chemical data for the resin rodlets of the pomeroy coal bed of the central appalachian basin indicate that resin rodlets have significantly lower atomic h c and o c ratios than do sclerenchyma strands and woody splinters the lower atomic h c and o c ratios of the resin rodlets correlate with the highest reflectance in the coal ball medullosan seed fern stem from the herrin no 6 coal bed of the illinois basin the reflectances of the resin rodlets woody splinters and sclerenchyma strands are similar and comparable to those of associated vitrinite in the coal ball stem and in the attached coal however resin rodlets and sclerenchyma strands in the attached coal have significantly higher reflectances similar to those of the pomeroy coal

the elkhorn mountains revisited new data for the late cretaceous paleomagnetic field of north america the late cretaceous portion of north america s apparent polar wander apw path is poorly known due to a dearth of suitable post 85 ma reference poles a paleomagnetic re investigation of elkhorn mountains volcanics 80 ma was initiated to fill this void and to determine the degree to which the onset of an apparent rapid episode of apw during this time interval correlates with known late cretaceous tectonic events a total of 249 paleomagnetic samples 30 sites were collected from three separate areas within the elkhorn mountains using both alternating field and thermal demagnetization a characteristic direction of magnetization was isolate at 15 sites a95 15 which passes a fold test at the 95 confidence level the mean pole calculated from site virtual geomagnetic poles is located at 80 3 n 189 5 e n 15 a95 9 6 k 16 8 interestingly the elkhorn mountains pole is not concordant with the cretaceous stillstand poles but is nearly coincident with the paleocene reference pole and the recently published pole for the adel mountains dated at 76 ma these new data suggest the onset of apw which brought the pole from its cretaceous position to near its early tertiary position occurred prior to 80 ma and the transition was exceedingly rapid the onset of this rapid apw now appears to coincide more closely in time with many of the significant late cretaceous tectonic events e g the laramide orogeny however since the elkhorn mountains volcanics are floored by a major east directed thrust and have undergone crustal scale deformation the data should be viewed with caution until more results are available for this time interval

mineralogical composition of late permian coal seams in the songzao coalfield southwestern china abstract coals from three seam sections in the songzao coalfield sw china are mainly high ash high sulphur semianthracites minerals within the songzao coals are mainly kaolinite pyrite or marcasite in some cases and quartz with various proportions of non kaolinite clay minerals carbonates feldspars and anatase the illite and mixed layer illite smectite i s are na rich in some of the datong coal samples the i s in the lower coals of the datong section is most likely an alteration product of dispersed volcanic ash due to the availability of necessary ions e g k na and mg in the marine influenced coal swamp organically bound na which was expelled from the organic matter with coal rank advance especially with anthracitization may have supplied additional na for the formation of na rich illite authigenic i s also occurs in a tonghua coal ply that is overlain by a mafic bentonite and underlain by an alkali tonstein potassium na and mg for the formation of such i s were probably derived from the leaching of the adjacent alkali tonstein and mafic bentonite although the marine water was also a possible supplier of the alkali elements authigenic i s is rare in coal plies that occur further away from the altered volcanic layer leaching of the volcanic claystones in the tonghua coal seam probably led to the formation of relatively abundant anatase and rhabdophane in the underlying coal ply fracture filling ree minerals probably ree hydroxides or oxyhydroxides also occurring in that coal ply crystallized from ascending ree rich hydrothermal fluids probably associated with contemporaneous volcanic activity

the occurrence of buddingtonite in super high organic sulphur coals from the yishan coalfield guangxi southern china abstract this paper discusses the identification abundance modes of occurrence and origin of buddingtonite and associated minerals in three lopingian coals from the yishan coalfield guangxi province southern china the coals of this coalfield are preserved within carbonate successions and are characterized by super high organic sulphur contents mostly 6 9 three different types of feldspars have been identified in these coals buddingtonite albite and minor k feldspar both the albite and k feldspar in the coal were largely derived from detrital materials of terrigenous origin although some were authigenically deposited they were subsequently subjected to corrosion dissolution by percolating fluids buddingtonite was derived largely from k feldspar via diffusion mechanisms through the substitution of k by nh4 the latter coming from decomposition of organic matter in the coal or from changes in the organic matter with rank advance a small proportion of the buddingtonite was also derived from albite through the replacement of na by nh4

influence of late cretaceous magmatism on the sevier orogenic wedge western montana late cretaceous large volume pluton emplacement and accompanying volcanism within the evolving western montana thrust wedge may have played important roles in determining the geometric and kinematic development of the thrust wedge thereby influencing patterns of sediment dispersal and subsidence in the adjacent foreland basin intrusion of the upper cretaceous boulder batholith and coeval eruption of the elkhorn mountains volcanics were focused mainly at the trailing margin of the lombard eldorado allochthon the resultant thick 16 17 km igneous culmination evolved over a relatively short interval 80 70 ma thickening the orogenic wedge to the point of supercritical taper and facilitating continued motion along the lombard eldorado thrust system thrust imbrication at the wedge toe and forelandward translation of the helena salient delivery of eroded volcaniclastic detritus from the thickened thrust wedge and accelerated basin subsidence due to thrust loading resulted in accumulation of a thick 4 5 km sequence of campanian maastrichtian volcaniclastic strata in the foreland basin livingston group the structural and sedimentological effects of this structural magmatic culmination are similar to those of basement cored culminations elsewhere in the sevier orogen and to the neogene central andean orogenic wedge

mineralogical analysis of coals as an aid to seam correlation in the gloucester basin new south wales australia abstract quantitative mineralogical analysis using a rietveld based x ray diffraction method has been carried out on a succession of permian coal seams and associated strata in a small but structurally complex area of the gloucester basin new south wales to identify criteria that will assist stratigraphic correlation the coals are relatively rich in mineral matter which is dominated by quartz illite and interstratified illite smectite of detrital and pyroclastic origin however the mineral matter in the coals typically contains higher proportions of kaolinite and lesser proportions of illite than the associated noncoal strata suggesting at least some leaching and reprecipitation of aluminosilicates in the original peat swamp when considered on a quantitative basis several of the seams contain distinctive assemblages in their mineral matter that can assist recognition of the seams in subsurface studies these include an increased abundance of pyrite and feldspar in the marine influenced upper glenview seam an increased abundance of well ordered kaolinite in the upper bowens road seam and a higher proportion of quartz in the lower avon seam the roseville seam also contains measurable proportions of phosphate minerals which are not detected in the other coal beds used in conjunction with other factors quantitative mineralogical studies using xrd thus appear to be sufficiently sensitive to allow discrimination between individual seams in a sequence even though the coals contain an abundant overprint of detrital and pyroclastic mineral components

mineralogy of the pennsylvanian coal seam in the datanhao mine daqingshan coalfield inner mongolia china genetic implications for mineral matter in coal deposited in an intermontane basin abstract this paper deals with the mineral matter in the coal and associated strata from the datanhao mine daqingshan coalfield which is closely located to the previously reported adaohai and hailiushu mines of the same coalfield the coal from the datanhao mine is mainly high ash and low sulfur bituminous the mineral assemblage in the coal is dominated by quartz kaolinite with varying proportions of carbonates calcite ankerite and siderite small proportions of muscovite illite pyrite and anatase the associated non coal claystone samples have similar mineral assemblage except that most non coal samples contains less quartz than the adjacent coal plies although deposited in the same intermontane basin of the orogenic belt the yinshan upland the datanhao coal seam shows different mineralogical characteristics from those of the nearby adaohai and hailiushu mines this may reflect the different sediment source regions during the peat accumulation stage the sediment source for the datanhao coal was probably the ordovician quartz rich sandstone or the sinan quartzite in the surrounding sub uplifts high proportions of quartz in the datanhao coal suggest intense terrigenous input into the paleomire and a short distance from the sediment source region different mineralogical characteristics of the coals from the three mines datanhao hailiushu and adaohai of the daqingshan coalfield are probably due to the different source material in their respective surrounding subuplifts within the intermontane basin kaolinite displaying graupen tabular and vermicular textures and the common presence of quartz in the intra seam non coal bands from the datanhao coal seam indicate that most of these bands are tonsteins altered airborne volcanic ash the original magma is probably high level volatile rich silicic in composition

fluid inclusion systematics in porphyry copper deposits the super giant grasberg deposit indonesia as a case study abstract fluid inclusion data provide a unique insight into the behaviour of magmatic fluids as they expand from source to surface to form porphyry copper deposits for example saline liquid phase inclusions in combination with vapor phase inclusions help to define the environment of mineralization in terms of large scale two phase fluid flow within a magmatic vapor plume however the pressure at which ore formation occurs within the plume is controversial because inclusion based estimates are commonly much higher than those based on geological estimates uniquely the grasberg supergiant porphyry copper deposit occupies the breccia filled diatreme underlying the crater of a maar volcano and preserved a lacustrine volcaniclastic sequence that marks the paleo surface to within a few hundred meters interpreting fluid inclusion data with respect to this paleo surface shows that porphyry mineralization extended from a paleo depth of about 500 m to over 1500 m depth as defined by drilling the grasberg deposit has three distinct populations of fluid inclusions low salinity hypersaline liquid and multi solid inclusions that are strongly clustered with respect to salinity and trapping temperature similar clusters of co existing liquid and vapor rich inclusions are also common to porphyry copper deposits worldwide applying the principles of energy and mass conservation a simple model of isenthalpic phase separation by condensation may be derived to account for these data clusters and how they are related vapor and liquid rich hypersaline inclusions may be shown quantitatively to be the consequence of expansion of a continuum low salinity low density magmatic vapor phase to a two phase fluid where the liquid fraction is minor the application of mass and energy conservation principles also shows that even though metal partitioning to the liquid phase may be favored the proportion of total metal fractionated to the small mass of liquid is low relative to that remaining in the vapor phase therefore while partitioning of metals between liquid and vapor phases may be a contributing process for metal deposition in porphyry copper deposits other vapor phase processes are required to efficiently deposit these major metal resources

thrust timing growth of structural culminations and synorogenic sedimentation in the type sevier orogenic belt western united states most of the regional shortening in the type area of the sevier orogenic belt in central utah was accommodated by displacement on the canyon range neocomian aptian pavant aptian albian paxton cenomanian campanian and gunnison late campanian paleocene thrust systems inception of each thrust system generated synorogenic sediment associated with frontal thrust tip anticlines or triangle zones and older thrust sheets that were elevated above major ramps farther toward the hinterland the sevier culmination a large antiformal duplex cored by crystalline basement rocks developed during paxton and gunnison thrusting west of and structurally beneath the canyon range and pavant thrusts growth of the sevier culmination was coeval with reactivation of the canyon range and pavant thrust systems and produced a second culmination in proterozoic lower cambrian rocks in the canyon range these structural highs provided much of the sediment to the adjacent foreland basin from late cenomanian to late paleocene time and may have helped to maintain critical taper in the thrust belt

geology and alteration geochemistry of the porphyry cu au deposit at bajo de la alumbrera argentina this paper describes the igneous geology alteration mineralogy and geochemistry as well as the ore mineralization history of bajo de la alumbrera a world class porphyry copper gold deposit in northwestern argentina the deposit occurs in the k rich calc alkaline farallon negro volcanic complex located 200 km east of the main andean porphyry copper belt of chile the deposit consists of a composite stock of dacitic porphyry intrusions and extends into the surrounding andesitic volcanic rocks two of the earliest intrusions now occupying the center of the intrusive complex show intense hydrothermal alteration and mineralization these two porphyries host the highest ore grades and were subsequently intruded by several weakly mineralized or barren porphyries intense quartz magnetite k feldspar alteration pervades the first mineralized porphyry whereas similar but lower intensity alteration affected the second laterally this alteration grades into potassic alteration secondary k feldspar and biotite which affects all porphyries except the latest dikes andesitic wall rocks within a hundred meters of the intrusions are dominated by dark hydrothermal biotite an outer halo of propylitic alteration epidote chlorite albite calcite extends up to 1 km into the andesites feldspar destructive alteration sericite pyrite clay minerals gypsum overprints the potassic and propylitic alteration in the volcanic rocks and all porphyries the alteration is locally controlled by faults and late fractures and developed most pervasively upon the outer part of the potassic zone and toward the transition to propylitic alteration in the upper part of the deposit mass balance calculations show small positive changes in net volume for the potassic alteration and minor volume decreases for the chlorite epidote and feldspar destructive alteration the intensely quartz magnetite veined sample of quartz magnetite alteration indicates a total volume increase of 350 percent copper and gold are intimately associated at all scales they occur as composite gold sulfide grains chalcopyrite rarely bornite show a close correlation of ore grades in sample assays and have a closely overlapping distribution on the mine scale a well developed ore shell coincides with potassic alteration and partly with the distribution of intense quartz magnetite veins even though the bulk of the ore minerals now occupy texturally late positions in vugs and fractures a barren zone with intense quartz magnetite potassic alteration and veins but little or no sulfides is interpreted as the focus of upflow of high temperature ore fluids prior to ore mineral saturation and coprecipitation of copper sulfides and gold in the ore shell

analysis origin and significance of mineral matter in coal an updated review abstract the material classed as mineral matter in coal embraces crystalline mineral materials as well as a range of inorganic elements that occur in non crystalline form this review outlines the methods that may be used to evaluate the percentage of mineral matter for a coal sample as opposed to the ash yield and to identify the minerals their individual percentages and their modes of occurrence within the coal the principal techniques include low temperature oxygen plasma ashing quantitative evaluation of x ray diffraction data observation using optical microscopy and a combination of observation chemical analysis and in some cases mapping based on scanning electron microscopy and related methods a range of other techniques may also be used to provide additional information on particular mineral matter components processes responsible for mineral matter formation include detrital input biogenic activity and authigenic precipitation at different stages of the coal s depositional and post depositional history differential migration of non mineral inorganic elements may also occur in lower rank coals and expulsion of non mineral inorganics may take place with rank advance knowledge of the mineral matter may be of assistance in understanding the modes of trace element occurrence with implications for assessing possible environmental impacts and also the potential for recovery of economic products from coal the behaviour of different mineral matter components at high temperatures is also discussed as well as methods for mineralogical analysis of ashes and other coal utilization products information from mineral matter studies may provide an improved basis for understanding coal formation and for evaluating the response of particular coals to different combustion gasification and coking processes

geological controls on mineralogy and geochemistry of the late permian coals in the liulong mine of the liuzhi coalfield guizhou province southwest china abstract this paper investigates the mineralogical and geochemical compositions of the late permian coals in the liulong mine liuzhi coalfield western guizhou province china by using xrd sem edx icp aes and icp ms both the no 3 and no 7 coals are classified as low volatile bituminous coal however the no 3 coal is a medium ash 29 8 on average and high sulfur 4 76 on average coal while the no 7 coal is a low ash 12 4 on average and medium sulfur 2 16 on average coal major minerals in both coal seams include quartz pyrite marcasite kaolinite calcite and to a lesser extent gypsum and anatase illite chlorite rectorite albite ankerite and siderotil are only present in the no 3 coal the no 3 coal contains higher elemental concentrations than the no 7 coal probably due to the higher mineral contents in the no 3 coal and is enriched in nb and ta and to a lesser extent in k ti li v co cu sr zr mo and ba the mineralogical and geochemical data presented in this study have shown that the no 3 coal was formed under a higher degree of marine influenced coal forming environment than the no 7 coal however the both coals have the kangdian upland made of mafic igneous rocks such as basalt rocks as sediment source region like other coals from guizhou province three geological factors control the geochemical patterns of the no 3 and no 7 coals namely 1 the high detrital input in the no 3 coal causing high ash yields 2 the sediment source region kangdian upland basalt causing high ti nb and ta contents and a minor proportion of co cr v and cu when combined with the high detrital input in the no 3 coal 3 the higher degree of marine influenced depositional environment in the no 3 coal causing a high s sr and ba contents

mineral occurrence and its impact on fracture generation in selected qinshui basin coals an experimental perspective abstract the effect of mineral matter on the fracture evolution was investigated for lower permian and upper pennsylvanian coal samples from the qinshui basin of china optical microscopy scanning electron microscopy with energy dispersive x ray spectrometry sem eds and x ray computed tomography x ray ct were used to investigate the composition and modes of occurrence of minerals within the coals and to characterize the natural and induced fractures present within the samples the spatial distribution of mineral matter investigated by x ray ct demonstrates that the variation of mineralization within the cleats fractures occurred at fine scales and most of minerals were scattered in coal core samples the original fractures normally were present as two sets one set was almost parallel to the bedding plane and the other was almost perpendicular to the bedding plane for created fractures the difference in density between the matrix and mineral matter may weaken the cohesion of coals and it could explain why the created fractures propagate along the junction of minerals and organic coal matrix the internal fracture porosities varied from 0 06 to 20 69 which indicates a strong internal heterogeneity of the coals after a stress is applied the inclination of the main shear fractures ranges from 55 to 95 using energy analysis the fracture energy appears to represent nearly half of the total dissipated energy which can be correlated with the fracture density and orientation the formation and distribution of shear fractures is related to the spatial distribution of mineral matter and the overall mineral content these investigations serve to characterize hydro fracturing and pulverized coal generation during coalbed methane development

quantification of crystalline mineral matter in some turkish coals using interactive rietveld based x ray diffractometry quantitative x ray diffractometry using a rietveld based computational method siroquant has been carried out for a series of coal samples from the various turkish mines standard proximate and ultimate analyses were carried out chemical compositions of the high temperature ash hta of coal samples were determined by x ray fluorescence xrf spectrometry technique crystalline mineral matter and amorphous content of raw coal samples were estimated the ca si al s and fe concentrations are higher than those of the other major elements ti mn mg na p k in the studied coal samples the percentage of crystalline mineral matter for each sample varies from 16 5 to 36 1 of the coal samples the minerals in the sampled coals consist mainly of quartz clay minerals calcite pyrite and gypsum percentages of crystalline mineral matter in ash content remarkably decrease for the elbistan orhaneli and tufanbeyli lower rank coals

mineralogical and geochemical anomalies of late permian coals from the fusui coalfield guangxi province southern china influences of terrigenous materials and hydrothermal fluids abstract the late permian coal in the fusui coalfield of southern china is characterized by high fe sulfide and organic sulfur contents 2 60 and 2 94 respectively trace elements including zr 354 g g on average hf 9 18 g g y and rare earth elements rey 302 g g li 97 9 g g and cs 7 02 g g are significantly enriched in these coals in addition to hg and se enrichment in the roof and floor of the coal fluorine mo and u are enriched in the roof the floor is rich in cl s fe pb and cd compared to the upper continental crust rey in the parting and coal bench samples are characterized by heavy rey and light rey enrichment respectively the coals partings and host rocks roof and floor have negative eu anomalies the coal benches have higher ratios of u th yb la nb ta and zr hf and more abundant heavy rare earth elements than their adjacent partings these geochemical anomalies are attributed to the composition of terrigenous materials derived from the yunkai upland multi stage syngenetic and epigenetic hydrothermal fluid activities and intensive leaching and re distribution of lithophile elements from partings to the underlying coal benches both the organic and sulfide sulfur are also derived mainly from the hydrothermal fluids rather than the marine influence the minerals in the samples studied including kaolinite quartz and ree bearing minerals are of both terrigenous and hydrothermal origin al oxyhydroxides crystalline feso 4 oh water bearing fe oxysulfate and goyazite were derived from the hydrothermal activity kaolinite quartz ree bearing minerals and apatite from the sediment source region were also subjected to destruction by hydrothermal fluid leaching

scanning electron microscope cathodoluminescence analysis of quartz reveals complex growth histories in veins from the butte porphyry copper deposit montana scanning electron microscope cathodoluminescence sem cl analysis of quartz reveals textures that cannot be observed using optical microscopy or backscattered electrons these cryptic textures yield insight into timing and physical conditions of quartz growth especially in environments with multiple quartz precipitation events hydrothermal quartz from quartz sulfide veins in the porphyry copper deposit in butte montana was analyzed by sem cl revealing the following textures euhedral growth zones wide nonluminescing bands that cut across multiple quartz grains rounded luminescent quartz grain cores with euhedral overgrowths nonluminescing splatters of quartz connected by networks of cobweb like nonluminescing quartz in otherwise luminescent quartz concentric growth zones and wide nonluminescent grain boundaries these textures indicate that many veins have undergone fracturing dilation growth of quartz into fluid filled space quartz dissolution and recrystallization of quartz precipitation and dissolution textures indicate that early quartz molybdenite veins formed as a result of pressure fluctuations between lithostatic and hydrostatic at high temperatures and later pyrite quartz veins formed near hydrostatic pressure in response to temperature decrease through and beyond the field of retrograde quartz solubility

distribution and origin of minerals in high rank coals of the south walker creek area bowen basin australia the coals of the south walker creek area in the northern bowen basin with a vitrinite reflectance rvmax of 1 7 to 1 95 are among the highest rank coals currently mined in australia x ray diffraction studies have identified an unusual mineral variation through the vertical sequence with kaolinite rich assemblages typical of other australian coals at the top and bottom of the seam section and an illite chlorite assemblage resembling a metamorphic association in the middle calcite and ankerite are also abundant in parts of the vertical sequence diaspore is abundant in the middle section of the seam in some areas and paragonite dickite or nacrite occurs in some locations as well the distribution of the non carbonate mineral assemblages cross cuts the seam stratigraphy and appears to be primarily controlled by faults and other structural features integration of the mineral distribution with optical and electron microscope data on the coal and non coal bands chemical data from coal ash analysis and information from x ray micro tomography suggests that the illite chlorite and diaspore bearing assemblages resulted from hydrothermal effects associated with fluid migration through the middle part of the coal seam this is further confirmed by the development of metamorphic textures in a tonstein band also altered to illite and chlorite in the illite rich part of the seam section in contrast to a tonstein with more normal sedimentary textures and a kaolinite composition in the kaolinite rich upper part of the seam detailed studies of cleat mineralisation suggest that fluids rich in ca mg and al were introduced relatively early in the seam s post depositional history associated with heat flow sufficient to alter the minerals in the coal and tonstein in the affected part of the seam section the relatively uniform vitrinite reflectance profile observed through the seam section may indicate that the coal was already of high rank before the fluids were introduced or that any localised heat effects on the organic matter associated with the changes in clay mineralogy were overprinted by subsequent wider ranging rank advance processes

mineralogy and geochemistry of a superhigh organic sulfur coal yanshan coalfield yunnan china evidence for a volcanic ash component and influence by submarine exhalation abstract the mineralogy and geochemistry of a superhigh organic sulfur shos coal of late permian age from the yanshan coalfield yunnan province southwestern china have been studied using optical microscope low temperature ashing plus x ray diffraction analysis scanning electron microscope equipped with energy dispersive x ray spectrometer a sequential chemical extraction procedure and inductively coupled plasma mass spectrometry the m9 coal from the yanshan coalfield is a shos coal that has a total sulfur content of 10 12 11 30 and an organic sulfur content of 8 77 10 30 the minerals in the coal consist mainly of high temperature quartz sanidine albite muscovite illite pyrite and trace amounts of kaolinite plagioclase akermanite rutile and dawsonite as compared with ordinary worldwide bituminous coals and anthracite and chinese coals the m9 coal is remarkably enriched in b 268 g g f 841 g g v 567 g g cr 329 g g ni 73 9 g g mo 204 g g and u 153 g g in addition elements including se 25 2 g g zr 262 g g nb 20 1 g g cd 2 07 g g and tl 2 03 g g are also enriched in the coal occurrence of high temperature quartz sanidine muscovite and illite in the m9 coal is evidence that there is a volcanic ash component in the coal that was derived from acid volcanic ashes fallen into the swamp during peat accumulation occurrence of albite and dawsonite in the coal and strong enrichment of some elements including f s v cr ni mo and u are attributed to the influence by submarine exhalation which invaded along with seawater into the anoxic peat swamp abundances of lithophile elements including rare earth elements nb y zr and tio2 indicate that the silicate minerals in the coal were derived from the northern vietnam upland to the south of the basin

chronology of exotic mineralization at el salvador chile by 40ar 39ar dating of copper wad and supergene alunite exotic copper mineralization is a complex hydrochemical process linking supergene enrichment lateral copper transport and precipitation of copper oxide minerals in the drainage network of a porphyry copper deposit at the el salvador porphyry copper deposit in northern chile the majority of the exotic ore comprised a mixture of copper bearing manganese oxyhydrates termed copper wad x ray diffraction scanning electron microscopy and electron probe microanalysis show that the copper wad is composed of copper bearing cryptomelane k1 2 mn3 mn4 8o16 x h2o and birnessite k0 33 batchmode documentclass fleqn 10pt legalpaper article usepackage amssymb usepackage amsfonts usepackage amsmath pagestyle empty begin document mn 7 3 9 end document o14 7h2o structures these natural occurrences within the exotic ore provide the opportunity to directly date the formation of these deposits using recent advances in 40ar 39ar geochronology of supergene k mn oxides formed by weathering a suite of copper bearing cryptomelane and birnessite samples from exotic deposits within the el salvador district were characterized and dated by 40ar 39ar laser step heating supergene alunite kal3 so4 2 oh 6 found in paleospring feeder systems leading from the source zones of copper outward to the exotic mineralization was dated to independently constrain the age of exotic ore formation although the ar retentivity of the layered birnessite structure has been questioned by others the ar retentivity of these samples is thought to be a function of their natural preservation and limited postcrystallization ground water interaction in the hyperarid atacama desert the 40ar 39ar analytical results show that ar and or k losses after crystallization excess 40ar and 39ar recoil do not pose significant problems therefore in the context of exotic copper deposits within hyperarid environments this dating method is applicable to both cryptomelane and birnessite within copper wad the 40ar 39ar dating of exotic mineralization at el salvador indicates that supergene and exotic mineralization processes were active at 35 ma about 5 m y after the emplacement of hydrothermal mineralization and continued until the middle miocene the majority of exotic mineralization extends from the oligocene miocene 24 ma boundary through the middle miocene 11 ma and relates to supergene fluid emanating in multiple directions from the source of copper in indio muerto which represents a topographic high above the exotic deposits one reconnaissance date of exotic mineralization at the chuquicamata porphyry copper deposit yielded an age of 17 03 0 03 ma coincident with the known supergene alunite dates for this deposit reconnaissance dating at exotica mina sur and el abra proved problematic due to the presence of contaminant silicate minerals within the copper wad ages derived here for exotic mineralization are similar to the known supergene ages throughout northern chile the dates indicate that supergene exotic mineralization began at the eocene oligocene boundary and continued through the oligocene eventually ceasing in the middle miocene due to desiccation of the atacama desert a series of 10 cm thick supergene alunite veins were microsampled across their widths and dated to address the kinetics of alunite vein growth apparent growth rates of the veins vary from 71 to 100 mm m y in the horizontal direction to 24 mm m y in the vertical presumably caused by differences in pressure regimes due to their orientation

shrimp u pb and 40ar 39ar age constraints for relating plutonism and mineralization in the boulder batholith region montana the composite boulder batholith montana hosts a variety of mineral deposit types including important silver rich polymetallic quartz vein districts in the northern part of the batholith and the giant butte porphyry copper molybdenum pre main stage system and crosscutting copper rich main stage vein system in the southern part of the batholith previous dating studies have identified ambiguous relationships among igneous and mineralizing events mineralizing hydrothermal fluids for these types of deposits and magma for quartz porphyry dikes at butte have all been considered to be late stage differentiates of the boulder batholith however previous dating studies indicated that the boulder batholith plutons cooled from about 78 to 72 ma whereas copper rich main stage veins at butte were dated at about 61 ma recent efforts to date the porphyry copper molybdenum pre main stage deposits at butte resulted in conflicting estimates of both 64 and 76 ma for the mineralizing events silver rich polymetallic quartz vein deposits elsewhere in the batholith have not been dated previously to resolve this controversy we used the u s geological survey stanford shrimp rg ion microprobe to date single age domains within zircons from plutonic rock samples and 40 ar 39 ar geochronology to date white mica biotite and k feldspar from mineral deposits u pb zircon ages are rader creek granodiorite 80 4 1 2 ma unionville granodiorite 78 2 0 8 ma pulpit rock granite 76 5 0 8 ma butte granite 74 5 0 9 ma altered steward type quartz porphyry dike i 15 roadcut 66 5 1 0 ma altered steward type quartz porphyry dike continental pit 65 7 0 9 ma and quartz monzodiorite of boulder baldy big belt mountains 66 2 0 9 ma zircons from rader creek granodiorite and quartz porphyry dike samples contain archean inheritance the 40 ar 39 ar ages are muscovite silver rich polymetallic quartz vein basin district 74 4 0 3 ma muscovite silver rich polymetallic quartz vein boulder district 74 4 1 2 ma muscovite early dark micaceous vein continental pit 63 6 0 2 ma biotite early dark micaceous vein continental pit 63 6 0 2 ma potassium feldspar early dark micaceous vein continental pit 63 to 59 ma and biotite biotite breccia dike continental pit 63 6 0 2 ma outlying silver rich polymetallic quartz veins of the basin and boulder mining districts probably are directly related to the 74 5 ma butte granite whereas steward type east west quartz porphyry dikes and butte pre main stage deposits are parts of a 66 to 64 ma magmatic mineralization system unrelated to emplacement of the boulder batholith the age of the crosscutting main stage veins may be about 61 ma as originally reported but can only be bracketed as younger than the 64 ma pre main stage mineralization and older than the about 50 ma eocene lowland creek intrusions the 66 ma age for the quartz monzodiorite of boulder baldy and consideration of previous dating studies in the region indicate that small ca 66 ma plutonic systems may be common in the boulder batholith region and especially to the east the approximately 64 ma porphyry copper systems at butte and gold mineralization at miller mountain are indicative of regionally important mineralizing systems of this age in the boulder batholith region resolution of the age and probable magmatic source of the butte pre main stage porphyry copper molybdenum system and of the silver rich polymetallic quartz vein systems in the northern part of the boulder batholith documents that these deposits formed from two discrete periods of hydrothermal mineralization related to two discrete magmatic events

230th and 231pa in the arctic ocean implications for particle fluxes and basin scale th pa fractionation abstract we report concentrations of 231pa 230th and 232th measured in unfiltered seawater samples from three stations occupied during the 1994 arctic ocean section at the western edge of the canada basin in the makarov basin and in the amundsen basin at the north pole the north pole data agree well with previously published profiles from the amundsen basin 230th and 231pa concentrations in the canada and makarov basins are intermediate between those reported previously for the beaufort sea and the alpha ridge reinforcing the observation that scavenging rates are variable in the western and central arctic and can be as rapid as in the eurasian basin and other oceans thorium 232 data indicate that relatively high rates of scavenging under the permanent ice cover are driven at least in part by offshore transport of detrital particulate material a comparison of water column 230th 231pa ratios throughout the arctic suggests that there may be little basin scale fractionation of these two isotopes in this ocean contrary to expectations based on the relatively large area of the continental shelves and their contrasts with the deep basins models of shelf basin exchange and 230th 231pa scavenging incorporating available constraints support this suggestion and point to the need for more data from the arctic shelves where the imprint of th pa fractionation if any is expected be most pronounced

mineral matter in low rank coals and associated strata of the mae moh basin northern thailand abstract the mineral and other ash forming constituents in lignites of the mae moh basin in northern thailand have been identified and evaluated in relation to the minerals present in the associated interseam non coal strata and the intra seam non coal bands treatment of the coal with water ammonium acetate and hydrochloric acid shows that a considerable part of the ash forming inorganic matter occurs in water soluble acid soluble or ion exchangeable form although the distribution of elements may be modified by the effects of pyrite oxidation the mobile fraction of the fresh coal is dominated by water soluble ion exchangeable and acid soluble calcium water soluble and exchangeable magnesium water soluble sodium and sulphur and acid soluble iron and aluminium calcium is most abundant especially in coals where a low proportion of silicate minerals quartz clay etc is present it combines readily with the different sulphur forms on combustion to produce an ash with a distinctively high cao and so 3 content the main minerals in the coals are quartz pyrite and a clay fraction consisting of kaolinite illite and an expandable irregular mixed layer mineral the mixed layer clay appears to be more abundant in the coal and illite less so than in the mudrocks of the associated non coal strata the non coal partings within the main seams contain quartz pyrite and a similar clay mineral assemblage but they also contain an abundance of calcite and or aragonite and in some cases consist entirely of carbonate minerals shell fragments and possibly plant replacement structures are present in some of these materials gypsum bloedite hexahydrite and other sulphate minerals and calcite are deposited as fracture fillings and surface coatings on some exposed open cut mine faces

seismic reflection profiling in the boulder batholith montana seismic reflection profiling combined with gravity data allows more exact determination of the geometry of the controversial boulder batholith of montana reveals laminated structure of the lower crust beneath the batholith and identifies the moho at a depth of 38 km the batholith has inward dipping contacts the dip being about 50 on the west side on the basis of seismic data and the depth to the batholith floor is constrained between 12 and 18 km indicating a great volume for the batholith the boulder batholith was emplaced between 80 and 70 ma during an eastward thrusting in the fold and thrust belt a presumed basal decollement of the thrust system might coincide with the batholith floor and may correspond to the top of the lower crustal layering at a depth of 18 km

some genetic implications of silica and aluminosilicates in peat and coal abstract the inorganic content of okefenokee peat in the absence of a significant detrital contribution is a function of sponge spicule phytolith and diatom abundance in addition to the degree of organic matter decomposition and the frequency of fires the detrital component quartz dominates ash composition where it is present no clear correlation has been observed between the inorganic content of coals examined in this study and their maceral composition vitrinite rich coals have a wide range of ash yield these observations suggest that the minerals have been introduced detritally rather than accumulated as a result of peat degradation quartz in the coals appears to be detrital and the presence of 2m 1 mica indicates that there is also a detrital contribution to the clay minerals present

clays and other minerals in coal seams of the moura baralaba area bowen basin australia abstract the clays and other minerals in a succession of late permian coals of high volatile bituminous to semi anthracite rank have been identified using low temperature oxygen plasma ashing and x ray diffraction and evaluated to identify the relative roles in mineral matter formation of detrital input early diagenesis in the peat swamp and late diagenesis associated with rank advance although well ordered kaolinite of probable early diagenetic origin is abundant throughout the succession the uppermost and lowermost seams of the sequence regardless of rank contain relatively abundant illite and or interstratified illite smectite along with a small but significant proportion of chlorite these clays are thought to be essentially of detrital origin washed or blown into the peat deposit in relative abundance during the establishment and subsequent overwhelming of an extensive and long lived swampy environment quartz is also abundant in the lower seams of the sequence especially close to the regional sediment source area illite is unusually abundant in the topmost seam in both high and low rank parts of the succession and thus appears to represent detrital input from a particular source material although significant changes are reported in the clays of the associated strata due to rank advance the principal effect of rank advance on the minerals in the coal itself appears to be the development of an ammonium illite and possibly some additional fine grained chlorite in the semi anthracite material isolation within the organic matter of the coal is thought to have inhibited access for ions such as k which might otherwise have become involved in metamorphic reactions and given rise to mineralogical changes commonly found in non coal sedimentary successions

mineralogical and geochemical compositions of the pennsylvanian coal in the adaohai mine daqingshan coalfield inner mongolia china modes of occurrence and origin of diaspore gorceixite and ammonian illite abstract aluminum hydroxide boehmite rich pennsylvanian coals of high volatile a bituminous rank were found previously in the jungar coalfield inner mongolia china this paper reports new results on 48 bench samples of the cp2 coal from the adjacent adaohai mine daqingshan coalfield inner mongolia and provides new insights into the origin and modes of occurrence of the minerals and elements present in the cp2 coal compared to the same coal in the adjacent mines the cp2 coal in the adaohai mine has a higher rank ro ran 1 58 which is attributed to igneous intrusions during the late jurassic and early cretaceous epochs the proportion of inertinite 35 3 in the coal is higher than that in other late paleozoic coals in northern china but lower than that in the jungar coals minerals in the cp2 coal include diaspore boehmite gorceixite calcite dolomite siderite clay minerals kaolinite and ammonian illite and trace amounts of anatase fluorapatite quartz and pyrite based on mineral proportions in the coal bench samples the cp2 coal may be divided into four zones i to iv from bottom to top the major mineral in zones i and iv is kaolinite zones ii and iii are mainly composed of ammonian illite diaspore boehmite gorceixite calcite dolomite and siderite diaspore boehmite and gorceixite forming materials were derived from oxidized bauxite in the weathered crust of the benxi formation in the sediment source region during peat accumulation however gorceixite may have formed earlier than diaspore the diaspore was derived from gibbsite that was subjected to dehydration by the heat of the igneous intrusions the ammonian illite may have been formed at a relatively high temperature by interaction of kaolinite with nitrogen released from the organic matter in the coal during metamorphism caused by the igneous intrusion the calcite and dolomite occur as epigenetic cell and fracture fillings and were probably derived from the igneous fluids compared to the common chinese and world coals the cp2 coal is enriched in cao 1 69 mgo 0 32 p2o5 0 214 f 207 g g ga 16 3 g g zr 446 g g ba 276 g g hg 0 33 g g and th 12 4 g g but has a lower sio2 al2o3 ratio due to the higher proportions of diaspore boehmite and gorceixite in the coal the f occurs mainly in gorceixite and fluorapatite the major carriers of ga are diaspore and kaolinite but not gorceixite barium mainly occurs in gorceixite and barite mercury was probably derived from the igneous intrusion and is distributed in both the organic matter and the minerals the elements are classified into five associations by cluster analysis groups a b c d and e group a represents a ree be y se ga ge sc in pb bi nb ta tio2 w hg sb zr hf th u association most of the elements in group a are lithophile elements that occur in aluminosilicate minerals group b sn te zn cd v as cr cu mo ni re is weakly correlated with ash yield and is associated with unidentified trace sulfide minerals elements in group c ad na2o al2o3 sio2 li k2o rb cs tl association probably occur in the clay minerals and diaspore group d consists of p2o5 ba f sr s and cl and with the exception of s they occur in minerals gorceixite and fluorapatite oxides of fe2o3 mno cao mgo make up group e and mainly occur in the carbonate minerals the coals are enriched in light rees and the lrees hrees have been highly fractionated with an average la yb n of 8 71 the heavy rees in the coals have a stronger organic affinity than the lrees

mineralogical and compositional characteristics of late permian coals from an area of high lung cancer rate in xuan wei yunnan china occurrence and origin of quartz and chamosite abstract some townships in xuan wei county yunnan province have one of the highest lung cancer mortality rates in china and the epidemic disease in the area has generally been attributed to the polycyclic aromatic hydrocarbons pahs released from domestic coal burning however the cancer causing culprit is not settled as tian tian l 2005 coal combustion emissions and lung cancer in xuan wei china ph d thesis university of california berkeley found nanometer quartz in these coals soot emissions and lung cancer tissues we have conducted mineralogical and geochemical studies of the coals from xuan wei for the purpose of shedding light on the minerals which may be related to the epidemic lung cancer in this paper abundances modes of occurrence and origins of minerals and elements in the coals from two mines in xuan wei have been studied using optical microscope low temperature ashing x ray diffraction analysis scanning electron microscope equipped with energy dispersive x ray spectrometer and inductively coupled plasma mass spectrometry the minerals in the coals are mainly composed of quartz chamosite kaolinite and calcite the particle size of quartz is rather small mostly less than 20 m and it is of authigenic origin chamosite occurs mainly as cell fillings the occurrence of quartz and chamosite indicates that they were derived from the hydrothermal fluids epigenetic calcite is derived from calcic fluids kaolinite is derived mainly from sediment source region of kangdian oldland to the west of coal basin the composition of xuan wei coal is high in sio2 fe2o3 tio2 cao mno v co ni cu and zn the high sio2 content is attributed to quartz and the fe2o3 content to chamosite the high mn and low mg contents in the coal indicate the inputs of hydrothermal fluids cao occurs mainly in epigenetic calcite elements ti co ni cu zn and rare earth elements were derived from the basaltic rocks at sediment source region

mineralogical and geochemical compositions of the coal in the guanbanwusu mine inner mongolia china further evidence for the existence of an al ga and ree ore deposit in the jungar coalfield abstract aluminum hydroxide boehmite and diaspore ga rey rare earth elements and y and al rich pennsylvanian taiyuan formation coals have previously been found in the jungar and daqingshan coalfields inner mongolia china gallium rey and al are potentially extractable and usable elements in combustion residues derived from these coals this paper reports new results on 50 bench samples of the no 6 coal from the guanbanwusu mine jungar coalfield inner mongolia and provides new data and evidence for the existence of an al ga rey ore deposit in the unique jungar coalfield the no 6 coal in the guanbanwusu mine has a low rank ro ran 0 56 and a low sulfur content st d 0 58 the proportion of inertinite in the coal 56 7 mineral free basis is higher than that of vitrinite 31 the minerals in the coal are mainly represented by kaolinite boehmite and chlorite along with variable proportions in some samples of calcite ankerite siderite and goyazite boehmite goyazite and part of the kaolinite were derived from bauxite in the weathered surface of the sediment source region ankerite calcite and siderite in the coal are of authigenic origin the chlorite in the guanbanwusu coals appears to have a chemical composition intermediate between cookeite and chamosite this mineral mainly occurs as cell fillings also indicating an authigenic origin and was probably derived from hydrothermal fluids a new mineral phase mainly composed of ti cl and fe is probably a ti bearing oxychloride or hydroxychloride compared to other chinese coals and to world hard coals the coal from the guanbanwusu mine is enriched in al2o3 9 34 p2o5 0 126 li 175 g g f 434 g g cl 1542 g g ga 12 9 g g sr 703 g g and th 12 9 g g but has a lower sio2 al2o3 ratio 0 74 due to the higher proportions of boehmite and goyazite in the coal the major carrier of p2o5 and sr is goyazite lithium mainly occurs in the chlorite cf cookeite kaolinite and possibly to a lesser extent illite fluorine in the coal has a major boehmite affinity but a small proportion may also occur in the organic matter and chlorite gallium in the coal largely occurs in goyazite chlorine is independent of other elements in the coal associated neither with moisture nor with organic matter but possibly occurring in molecular form cl2 and in the ti bearing oxychloride or hydroxychloride thorium in the coal occurs in the clay and accessory minerals and was mainly derived from detrital materials of the source region rare earth elements and y have a mixed organic and inorganic affinity largely occurring in goyazite group minerals and to a lesser extent boehmite and organic matter most coal benches and partings have either an l type or h type of rey enrichment owing respectively to the weathered bauxite source region and groundwater effects the al2o3 ga rey and possibly li in the guanbanwusu coals like those in coals from the jungar and adjacent daqingshan coalfields are industrially useful metals that could potentially be recovered from the relevant coal combustion residues it is suggested that if ga in ash 50 g g rey 800 900 g g sio2 al2o3 40 in ash and coal thickness 5 m the coal combustion residues would be expected to be suitably enriched in al2o3 and can be considered for al2o3 ga and rey recovery

timing of porphyry cu mo and base metal zn pb ag cu mineralisation in a magmatic hydrothermal system morococha district peru the morococha district in central peru is characterised by economically important cordilleran polymetallic zn pb ag cu vein and replacement bodies and the large toromocho porphyry cu mo deposit in its centre u pb re os and 40ar 39ar geochronology data for various porphyry related hydrothermal mineralisation styles record a 3 5 ma multi stage history of magmatic hydrothermal activity in the district in the late miocene three individual magmatic hydrothermal centres were active the codiciada toromocho and ticlio centres each separated in time and space the codiciada centre is the oldest magmatic hydrothermal system in the district and consists of a composite porphyry stock associated with anhydrous skarn and quartz molybdenite veins the hydrothermal events are recorded by a titanite u pb age at 9 3 0 2 ma and a molybdenite re os age at 9 26 0 03 ma these ages are indistinguishable from zircon u pb ages for porphyry intrusions of the composite stock and indicate a time span of 0 2 ma for magmatic hydrothermal activity the small ticlio magmatic hydrothermal centre in the west of the district has a maximum duration of 0 3 ma ranging from porphyry emplacement to porphyry mineralisation at 8 04 0 14 ma 40ar 39ar muscovite cooling age the toromocho magmatic hydrothermal centre has a minimum of five recorded porphyry intrusions that span a total of 1 3 ma and is responsible for the formation of the giant toromocho cu mo deposit at least two hydrothermal pulses are identified post dating a first pulse of molybdenite mineralisation wide spread hydrous skarn covers an area of over 6 km2 and is recorded by five 40ar 39ar cooling ages at 7 2 6 8 ma these ages mark the end of the slowly cooling and long lived toromocho magmatic hydrothermal centre soon after last magmatic activity at 7 26 0 02 ma district wide 50 km2 cordilleran base metal vein and replacement bodies post date the youngest recorded porphyry mineralisation event at toromocho by more than 0 5 ma polymetallic veins 5 78 0 10 and 5 72 0 18 ma 40ar 39ar ages and the manto italia polymetallic replacement bodies 6 23 0 12 and 6 0 0 2 ma 40ar 39ar ages are interpreted to have been formed by a single hydrothermal pulse hydrothermal activity ceased after the formation of the base metal vein and replacement bodies overlapping monazite u pb 8 26 0 18 ma and muscovite 40ar 39ar ages 8 1 0 5 ma from the early base metal stage of one cordilleran vein sample in the sulfurosa area provide evidence that a discrete hydrothermal pulse was responsible for polymetallic vein formation 2 6 ma prior to the district wide polymetallic veins these ages pre date those of toromocho porphyry cu mo formation and show that zn pb ag cu mineralisation formed during several discrete magmatic hydrothermal pulses in the same district

mineralogy of lignites and associated strata in the mavropigi field of the ptolemais basin northern greece the mineralogy of five lignite layers and the associated roof floor and intercalating strata has been analysed using low temperature oxygen plasma ashing and quantitative x ray diffraction techniques the lignite contains quartz kaolinite illite and smectite and in some cases small proportions of feldspar thought to represent mainly detrital minerals in the original peat deposits one sample also contains crystalline calcium oxalates with weddellite present in the raw lignite and whewellite in the low temperature ash lta of the same lignite sample minor proportions of gypsum are present in some of the raw lignite samples possibly in part derived from precipitation of dissolved ca and so4 in the pore waters on drying all the ltas however contain much higher proportions of bassanite and or gypsum compared to the other minerals present consistent with production of calcium sulphate artefacts from interaction of abundant organically associated ca and s in the lignite during the plasma ashing procedure the inorganic strata are mainly carbonate rocks consisting almost entirely of calcite with minor aragonite small proportions of illite traces of pyrite and in some cases siderite some non carbonate rocks are also associated with the lignite seams these are dominated by plagioclase feldspar and mica along with illite kaolinite and a relatively minor proportion of quartz the mineral assemblages can be related to the palaeoenvironmental conditions under which the various sediments including lignite were deposited comparison of the mineral abundances in the samples to the chemical composition of the materials shows that the quantitative xrd technique provides results consistent with ash analysis data although abundant in the associated rocks calcite does not occur in the lignite samples while part of the relatively abundant ca in the lignite occurs as either gypsum or weddellite most of it appears to be organically bound mine products that incorporate calcareous rocks of the type associated with the lignite may however contain separate calcite phases and display high carbonate co2 contents

a new late cretaceous paleomagnetic pole from the adel mountains west central montana north america s apparent polar wander path has been poorly defined between the mid cretaceous and paleocene reference pole positions existing data allowed 13 of apparent polar motion over about 22 m y 87 65 ma roughly coinciding with the beginning of laramide deformation 80 ma we report on a paleomagnetic study of the adel mountain volcanic rocks to refine the north american apparent polar wander path for this interval the shonkinite rocks of the adel mountain volcanic field are on the eastern edge of the cretaceous paleocene fold and thrust belt some of these structures disturb the western edge of the volcanic pile we obtained two new k ar dates from the adel rocks one date on biotite from a shonkinite dike that crosscuts most of the volcanic rocks is 71 2 2 7 ma the other a whole rock date from a flow deep in the volcanic pile is 81 1 3 5 ma we collected six to nine paleomagnetic samples from each of 34 sites in roadcuts and natural outcrops of flows dikes and laccoliths positive fold and conglomerate tests along with alternating field and thermal demagnetization indicate that our characteristic remanent directions are primary magnetizations acquired before late cretaceous to paleocene thrust belt deformation averaging the virtual geomagnetic poles from 26 reliable sites all of normal polarity yields a paleopole at 82 2 n 209 9 e 95 6 80 k 18 38 this pole is concordant with the paleocene reference pole 82 0 n 170 2 e 95 3 5 k 18 6 diehl et al 1983 and is 11 6 from the globerman and irving 1988 mid cretaceous pole at 71 n 196 e the youngest information in the cretaceous stillstand pole is from the niobrara formation shive and frerichs 1974 at about 85 89 ma if we take the average age of the adel mountain volcanics to be 76 ma then 12 of apparent polar motion occurred between 87 ma and 76 ma thus rapid apparent polar motion correlates well with the onset of laramide deformation

paleogeographic and paleotectonic setting of laramide sedimentary basins in the central rocky mountain region in the rocky mountain region between central montana and central new mexico sedimentologically isolated nonmarine basins were produced by basement deformation during the laramide orogeny within the area formerly occupied by a broad late cretaceous foreland basin in which laterally continuous marine facies had accumulated previously laramide structures of varying trend and scale reflect heterogeneity of crustal strain caused by shear between the continental lithosphere and an underlying subhorizontal slab of subducted oceanic lithosphere laramide basins include perimeter basins along the cratonic periphery of the arcuate laramide province axial basins along a north south intramontane trend and ponded basins located farther west closer to the overthrust belt twelve specific stratigraphic and sedimentologic criteria for the onset duration and termination of laramide deformation allow the chronology of basin development to be inferred independently for each basin maastrichtian initiation of laramide deformation was approximately synchronous throughout the laramide province but termination of laramide deformation was systematically diachronous from north to south between early and late eocene time widespread eocene erosion surfaces truncate syntectonic laramide sequences and are overlain by largely volcanic and volcaniclastic post laramide strata of eocene age in the north and oligocene age in the south fluvial depositional systems draining toward the great plains were dominant in perimeter and axial basins but ponded basins were occupied at times by large lakes that served as regional sediment traps paleocene drainages from ponded basins also led eastward toward the continental interior but partly interconnected lakes that developed within several ponded basins by mid eocene time were either closed hydrologically or else they drained westward into the tyee paleoriver of the pacific northwest

two event lode ore deposition at butte usa 40ar 39ar and u pb documentation of ag au polymetallic lodes overprinted by younger stockwork cu mo ores and penecontemporaneous cu lodes abstract the ore genesis model for world class deposits of the butte mining district montana usa is deep pre main stage porphyry cu mo and overlying main stage ag zn cu zoned lode deposits both of which formed from hydrothermal fluids driven by minor volumes of rhyolitic magma the lode specific model is that hydrothermal processes diminished in intensity outward from district center along lode veins synchronously forming metal zones the accepted models are controverted by new geologic and multi method geochronologic studies the new data reveal the following sequence of events 1 thermal study of country rock indicates that the 76 9 ma butte granite cooled to 350 400 c by 4 m y after emplacement 2 five quartz porphyry rhyolite dikes were emplaced at 67 65 ma and another at 60 ma shrimp u pb into the cooled butte granite without resetting 40ar 39ar ages in country rock 3 fifty eight white mica and k feldspar samples from alteration envelopes adjacent to ag au polymetallic lodes in outer parts of the district zn rich lodes in intermediate parts and cu rich lodes in the district center yield 40ar 39ar ages of 73 70 ma for ag rich lodes 65 64 ma for cu rich lodes and complex age spectra of 69 65 ma for zn rich lodes the data show that ag au polymetallic lodes occupied cross district fractures by about 73 ma forming the greater butte mining district at 67 65 ma minor quartz porphyry dikes were emplaced into central and eastern parts of the rejuvenated fracture system but without evidence of related cupola or volcanic rocks or of thermal disturbance in the country rock at 64 5 ma overlapping hydrothermal cells formed two stockwork cu mo domes in deep parts of the fracture system at 65 64 ma and closely related to late stage stockwork cu mo activity a penecontemporaneous hydrothermal pulse formed a high sulfidation hydrothermal plume that 1 utilized the large re opened fractures to cannibalize and remobilize cu from autologous stockwork and older ag au polymetallic lodes 2 deposited the rich high sulfidation cu lodes and 3 mobilized metals from early ag au polymetallic veins in middle parts of the district transported the metals outward and redeposited them enriching early veins especially in the intermediate zn plus cu areas metals zones in lodes of the butte district are the result of an intensely focused cu rich hydrothermal plume that variably reworked the center of significantly larger 10 m y older ag au polymetallic lodes

mineralogy and sulfur isotope geochemistry of polymetallic porphyry epithermal mineralization peripheral to the golden sunlight gold mine montana abstract the golden sunlight mine located 50 km east of the famous butte porphyry lode deposit is the largest gold mine in montana and has produced over 3 6 m oz of gold in its 36 year history most of this gold has come from the mineral hill breccia pipe mhbp a west plunging cylindrical body of brecciated latite porphyry and siliciclastic sedimentary rocks of the mesoproterozoic belt supergroup this paper focuses on four areas of mineralization outside the mhbp termed the apex bonanza north pit and 102 sunlight zones the apex and 102 sunlight areas consist of auriferous pyrite rich veins cutting precambrian sediments and the cambrian flathead quartzite whereas the bonanza and north pit areas are polymetallic mo cu ag au prospects hosted in latite porphyry and belt sediments recent dating 40ar 39ar of igneous biotite shows the porphyry at bonanza was emplaced at 78 1 ma which is several m y younger than the porphyry associated with the mhbp 81 9 1 9 ma zircon u pb and several m y older than the main phase of the boulder batholith that hosts the butte deposit overall the ore and gangue mineral assemblages in the peripheral deposits are similar to those described previously for the mhbp deposit pyrite locally as rich is abundant in all settings with varying amounts of galena sphalerite chalcopyrite bornite molybdenite at bonanza tetrahedrite tennantite and traces of pearceite tetradymite aikinite calaverite petzite goldfieldite buckhornite gold and electrum gangue minerals include quartz carbonates fe dolomite siderite magnesite barite anhydrite adularia and alumino phosphate sulfate aps minerals spectral analysis indicates that some of the adularia is ammonium rich i e buddingtonite values of 34s for sulfide minerals from the peripheral deposits overlap with values obtained by previous workers from the mhbp the bulk of the analyses including all samples from the porphyry hosted bonanza deposit have 34s values between 12 and 4 with a tail to heavier values 5 it is postulated that most of the lighter s was introduced into the district by late cretaceous magmatic hydrothermal fluids whereas the heavier s is attributed to sedimentary pyrite in the precambrian greyson and lahood formations a weak negative correlation exists between gold grade and the 34s of associated pyrite all samples in this study that contain 0 1 oz ton au have 34s reduced s

geology mineralization alteration and structural evolution of the el teniente porphyry cu mo deposit sir the el teniente cu mo deposit in central chile is an extraordinary accumulation of cu mo ore fig 1 and we welcome the opportunity provided by skewes and stern 2007 to discuss and clarify several important issues regarding its classification and interpretation and to address several incorrect assertions that they make regarding our manuscript cannell et al 2005 we have interpreted el teniente to be a typical porphyry deposit in terms of its alteration assemblages vein and breccia styles and spatial and temporal relationships between cu mo mineralization and felsic porphyries skewes and stern 2007 dispute our claims that mineralization occurred primarily in veins and was related to felsic intrusive activity they also take issue with our interpretations of the various geochronological datasets from el teniente and our classification of el teniente as a porphyry cu mo deposit we address each of these in turn below in order to facilitate the following discussion table 1 correlates the geologic nomenclature of skewes and stern 2007 with that of cannell et al 2005 figures 1 and 2 illustrate the location of the main geologic units on underground mine level 6 at el teniente also shown on figure 1 are the approximate locations of the hypogene sulfide mineral zones figure 2 shows the block model of mo grades in the mine for more details of geologic relationships at el teniente refer to figure 4 of cannell et al 2005 and figures 4 and 5 of skewes et al 2002 although the dacite porphyry dike is shown as a single unit on figure 1 note that rojas 2002 2003 mapped multiple phases within this composite intrusive body skewes and stern 2007 criticized our use of what they assert to be an outdated map of hypogene mineralization

mineralogical and geochemical characterization of the saray and pinarhisar coals northwest thrace basin turkey abstract this study investigates the mineralogical and geochemical characteristics of coals from the saray and pinarhisar coalfields in the northwest thrace basin using optical microscopy scanning electron microscopy x ray diffraction and inductively coupled plasma mass spectrometry the saray and pinarhisar coals were deposited in a limnic environment the sulfur content of the coals ranges from 0 3 to 15 3 and high sulfur contents may originate from both seawater and volcanism pyritic and organic sulfur are the dominant sulfur forms 1 2 and 2 7 on average respectively the mineral matter of the coals consists mainly of pyrite barite gypsum muscovite and kaolinite with minor amounts of quartz butlerite tamarugite and rozenite the coals are enriched in trace elements including v 61 ppm on average co 5 85 ppm on average ni 79 ppm on average as 39 2 ppm on average th 3 6 ppm on average and u 6 7 ppm on average based on pearson correlation coefficients ti v cr fe co ni cu se rb au hg pb and th have mainly inorganic affinities r ash elements 0 5 in the pinarhisar coals fe as and au also have inorganic affinities r ash elements 0 5 in the saray coals the element contents and correlation coefficients indicate that the strandja massif the tethyan ophiolite belt and the oldest basement sediments were included in the sediment source region for both coalfields while the strandja massif was the prevailing sediment source region for pinarhisar coalfield

40ar 39ar and re os geochronology of porphyry copper molybdenum deposits and related copper silver veins in the collahuasi district northern chile the rosario and ujina porphyry cu mo deposits together with porphyry copper mineralization at the nearby quebrada blanca deposit constitute the third largest concentration of copper mineralization associated with the domeyko fault system in northern chile at rosario fault hosted cu ag rich massive sulfide veins are associated with pyrophyllite alunite quartz altered rocks the rosario massive sulfide veins cut biotitealbite magnetite k feldspar and illite chlorite altered rocks associated with porphyry style copper molybdenum mineralization similar massive sulfide veins occur in the la grande area 1 to 2 km south of rosario copper ore at ujina is associated with a k feldspar biotite altered quartz monzonite intrusion the k feldspar biotite assemblage has been overprinted by white mica chlorite alteration new geochronologic data presented in this paper constrain the ages of hydrothermal activity in the rosario and ujina deposits the 40ar 39ar biotite illite and alunite dates at 2 sigma error and a re os molybdenite date at 0 5 error are reported for porphyritic rocks and hydrothermal alteration from the rosario and ujina mineralized centers a weighted mean 40ar 39ar plateau age of 34 4 plus or minus 0 3 ma is obtained for igneous biotite in a monzonite porphyry that hosts copper mineralization at the rosario deposit illite and hypogene alunite from separate overprinting alteration events yielded 40ar 39ar ages of 34 5 plus or minus 0 5 ma plateau age and 32 6 plus or minus 0 3 ma plateau age respectively an re os age of 33 3 plus or minus 0 2 ma for molybdenite at rosario is slightly younger than the 40ar 39ar age of illite but older than the alunite a weighted mean plateau age of 32 7 plus or minus 1 6 ma for hypogene alunite from the la grande cu ag au vein south of rosario is indistinguishable from the age of rosario alunite at ujina the weighted mean 40ar 39ar plateau age of igneous biotite for a monzonite intrusion that hosts copper mineralization is 35 2 plus or minus 0 3 ma the monzonite is intruded by postmineralization porphyry dikes of similar composition from which igneous biotite yielded a 40ar 39ar age of 34 7 plus or minus 0 3 ma igneous biotite in the rosario porphyry cooled through its closure temperature during and after the formation of illite implying that porphyry style ore and alteration minerals in the rosario deposit had formed by 34 3 ma the age of alunite at rosario and la grande indicate that a second discrete episode of hydrothermal activity was superimposed 1 8 plus or minus 0 4 m y later onto the earlier formed porphyry cu system hydrothermal activity at ujina is constrained by the 40ar 39ar ages of igneous biotite in the premineralization and postmineralization intrusions and occurred during a minimum interval of 0 5 plus or minus 0 4 m y the biotite granite at la profunda 1 5 km east of ujina has a igneous biotite age of 81 2 plus or minus 2 9 ma indicating that this intrusion is unrelated to the mineralized eocene oligocene porphyry intrusions at ujina rosario and quebrada blanca the 40ar 39ar data for igneous biotite in the rosario and ujina porphyries are cooling ages after multiple hydrothermal events in most cases these are minimum hydrothermal ages i e ages of the last high temperature hydrothermal event to have affected the samples not magmatic ages however the biotite age for the inca porphyry is possibly only slightly younger than the intrusion age because biotite has not been affected by later hydrothermal alteration

sequence stratigraphy of cenozoic continental rocks southwestern montana because the presently used bozeman group lithostratigraphy is difficult to apply to cenozoic basin fill rocks in the jefferson beaverhead melrose and divide valleys southwestern montana we advocate the use of sequence stratigraphy surface sequence boundaries are in many cases marked by calcic paleosol zones these zones can be projected into the subsurface and tied to seismic reflection data density velocity contrasts between calcic paleosol zones and overlying nonpedogenic rocks generate bright reflectors that define sequence boundaries sequence boundary delineation is further enhanced by reflection termination patterns similar to those found in marine strata sequence age calibration is based upon vertebrate fossil and radiometric age data five sequences separated by basin wide unconformities are recognized most sequence bounding unconformities are marked by paleosols an occurrence not previously reported for cenozoic strata of southwestern montana the sequences and their age ranges are 1 bridgerian uintan approximately 50 to 44 ma calc alkaline volcanic flows and interstratified sedimentary rocks 2 duchesnian to whitneyan approximately 42 to 30 ma terrestrial sedimentary and volcanic rocks 3 arikareean approximately 27 to 21 ma terrestrial sedimentary and volcanic rocks 4 barstovian to blancan approximately 16 to 4 ma terrestrial sedimentary and volcanic rocks and 5 early quaternary approximately 1 8 ma to holocene terrestrial sedimentary and volcanic rocks

paleomagnetic and isotopic dating of thrust belt deformation along the eastern edge of the helena salient northern crazy mountains basin montana thrust belt deformation along the eastern edge of the disturbed belt in the helena salient of montana has not been well dated owing to a lack of syn or postorogenic strata in situ paleomagnetic data from alkaline intrusions exposed in the easternmost folds of the salient in the northern crazy mountains basin previously described as pre syn or posttectonic with respect to deformation are well grouped dec 343 inc 61 95 5 0 k 46 n 16 sites a negative fold test is significant at minimally 95 confidence intrusion and magnetization acquisition thus postdate fold and thrust deformation k ar age determinations of selected intrusions range from 52 to 48 ma paleomagnetic and isotopic age data combined with stratigraphic information indicate that folding in the northern crazy mountains basin is middle to late paleocene in age this age is in agreement with suggested dates for deformation in the northern montana disturbed belt but is recognizably older than the youngest episodes of frontal deformation in the utah idaho wyoming salient data from this study and existing structural and stratigraphic information demonstrate that deformation in the overthrust belt and foreland provinces of southwest montana overlapped temporally and spatially ranged from late cretaceous to earliest eocene in age and progressed from west to east through time

mineralogical and geochemical responses of coal to igneous intrusion in the pansan coal mine of the huainan coalfield anhui china the huainan coalfield where magma is commonly intruded into the coal measures in the northern section e g the zhuji dingji pansan and panbei mines is the largest energy base in eastern china to investigate the mineralogical and geochemical responses of coal to igneous intrusion minerals major and trace elements in sandstone thermally altered coal igneous rock sandy mudstone and unaltered coal samples were collected from a representative profile of the no 1 coal of the pansan coal mine the samples were analyzed using an optical microscope powder x ray diffraction scanning electron microscopy in conjunction with x ray energy dispersive spectroscopy x ray fluorescence inductively coupled plasma atomic emission spectrometry and mass spectrometry the results indicated that the thick sill transformed from mafic rocks at the bottom via intermediate rocks in the middle to felsic rocks at the top of the profile the moisture total sulfur and carbon contents of the coal increased whereas volatile matter hydrogen and nitrogen decreased during contact metamorphism caused by igneous intrusion epigenetic minerals i e dolomite quartz and pyrite occurred in the thermally altered coals three stages of hydrothermal fluids i e ca mg and fe rich si rich and fe and or h2s rich solutions were identified iron ca s si mg zn cd and pb were transported into the thermally altered coal by hydrothermal fluids the concentrations of co and ni in the thermally altered coal increased in relation to the increase of ash yields that were caused by contact metamorphism whereas the b in the coal was volatilized manganese is directly related to the intrusive magma phosphorus ge and sr might be introduced into the coal by groundwater however k na ga and ba were leached out titanium sc cr v cu zr nb and rare earth elements and yttrium rey in the coals originated from terrigenous input and were not influenced by igneous intrusion

fault controlled pluton emplacement in the sevier fold and thrust belt of southwest montana usa abstract problems associated with syncompressional pluton emplacement center on the need to make room for magma in environments where crustal shortening not extension occurs on a regional scale new structural data from the pioneer and boulder batholiths of southwest montana usa suggest emplacement at the top of frontal thrust ramps as composite tabular bodies at crustal depths between 1 and 10 km frontal thrust facilitated pluton emplacement was accommodated by 1 a magma feeder zone created along the ramp interface 2 providing releasing steps at ramp tops that serve as initial points of emplacement and subsequent pluton growth and 3 localizing antithetic back thrusts that assist in pluton ascent a model of magma emplacement is proposed that involves these elements this model for syntectonic ramp top emplacement of plutons helps explain how space is made for plutons within fold and thrust belts

mineral matter and trace elements in coals of the gunnedah basin new south wales australia abstract the concentrations of major and trace inorganic elements in a succession of permian coals from the gunnedah basin new south wales have been determined by x ray fluorescence techniques applied to both whole coal and high temperature ash samples the results have been evaluated in the light of quantitative data on the minerals in the same coals determined from x ray diffraction study of whole coal samples using a rietveld based interpretation program siroquant to determine relationships of the trace elements in the coals to the mineral species present comparison of the chemical composition of the coal ash interpreted from the quantitative mineralogical study to the actual ash composition determined by xrf analysis shows a high degree of consistency confirming the validity of the xrd interpretations for the gunnedah basin materials quartz illite and other minerals of detrital origin dominate the coals in the upper part of the sequence whereas authigenic kaolinite is abundant in coals from the lower part of the permian succession these minerals are all reduced in abundance however and pyrite is a dominant constituent in coals formed under marine influence at several stratigraphic levels calcite and dolomite occur as cleat and fracture infillings mostly in seams near the top and bottom of the sequence the potassium bearing minerals in the detrital fraction are associated with significant concentrations of rubidium and the authigenic kaolinite with relatively high proportions of titanium zirconium is also abundant with associated p and hf in the gunnedah basin coal seams relationships exhibited by ti zr nd and y are consistent with derivation of the original sediment admixed with the seams from an acid volcanic source pyrite in the coals is associated with high concentrations of arsenic and minor proportions of thallium no other element commonly associated with sulphides in coals however appears to occur in significant proportions with the pyrite in the sample suite small concentrations of cl present in the coal are inversely related to the pyrite content and appear to represent ion exchange components associated with the organic matter strontium and barium are strongly associated with the cleat filling carbonate minerals ge and ga appear to be related to each other and to the coal s organic matter cr and v are also related to each other as are ce la nd and pr but none of these show any relationship to the organic matter or a particular mineral component

mineralogical and geochemical compositions of the pennsylvanian coal in the hailiushu mine daqingshan coalfield inner mongolia china implications of sediment source region and acid hydrothermal solutions abstract this paper investigates the mineralogical and geochemical compositions of the pennsylvanian coal in the hailiushu mine daqingshan coalfield neighboring previously reported al ga ree ore deposits including the adaohai mine in the same coalfield and deposits in the jungar coalfield using optical microscopy field emission scanning electron microscopy x ray fluorescence and inductively coupled plasma mass spectrometry the mineralogical and geochemical compositions in the coal were primarily controlled by the sediment source region during peat accumulation and by epigenetic acid hydrothermal solutions the hailiushu coal was deposited in a sub depression intermontane basin in the inner part of the orogenic belt with a sediment source region composed mainly of cambrian ordovician strata and archaean metamorphic rocks the minerals in the coal from the hailiushu mine dominantly consist of kaolinite with minor amounts of quartz sulfide and selenide minerals including chalcopyrite selenian galena galena sphalerite clausthalite and siegenite aluminophosphates and rhabdophane the coal is enriched in sio2 17 05 on average tio2 0 60 al2o3 13 71 zr 289 g g hf 7 09 g g and to a lesser extent f sc v cu ga se y nb mo cd sn la ta w hg pb bi and th titanium largely occurs in the kaolinite elements such as cu se sn hg pb and bi in the coal mainly occur in sulfide and or selenide minerals zirconium hf and nb were largely derived from the sediment source region the substitution of ti for al in kaolinite the corrosion of previously formed zircon anatase and quartz and the enrichment of middle rare earth elements in the coal were caused by the epigenetic acid hydrothermal solutions

palaeoenvironmental reconstruction of the cardak coal seam sw turkey abstract the study focuses on the firstly documented cardak coal seam cored in the neogene acigol basin denizli province being formed in a late stage of alpine orogeny in sw turkey the aim is to contribute reconstructing the palaeoenvironmental conditions before during and after coal formation on the basis of coal petrology mineralogical and palaeontological data combined with the results of previous studies the basin infilling consists of alluvial fluvial and lacustrine sediments their deposition depended on the water level in the basin which in turn was controlled by the interplay between tectonics and climate coal seam was probably formed in latest miocene early pliocene under the influence of basin s fluvial regime in oxbow and terminal lakes the coal seam comprises alternating inorganic and coal layers logged between depths of 599 00 to 627 00 m beneath surface the coal being lignite to subbituminous in rank displays moderate to high ash yield 21 31 46 11 wt on dry basis and high total sulphur content up to 13 30 wt on dry ash free basis the maceral composition points to an origin from mainly herbaceous helophytes along with woody species in the upper part of the core the presence of salinity tolerant ostracod species along with gypsum and halite are documented the palaeontological and mineralogical data obtained imply changes of climate water level and lake chemistry in the basin

mineralogy and geochemistry of the no 6 coal pennsylvanian in the junger coalfield ordos basin china abstract this paper discusses the mineralogy and geochemistry of the no 6 coal pennsylvanian in the junger coalfield ordos basin china the results show that the vitrinite reflectance 0 58 is lowest and the proportions of inertinite and liptinite 37 4 and 7 1 respectively in the no 6 coal of the junger coalfield are highest among all of the late paleozoic coals in the ordos basin the no 6 coal may be divided vertically into four sections based on their mineral compositions and elemental concentrations a high boehmite content mean 6 1 was identified in the no 6 coal the minerals associated with the boehmite in the coal include goyazite rutile zircon and pb bearing minerals galena clausthalite and selenio galena the boehmite is derived from weathered and oxidized bauxite in the weathered crust of the underlying benxi formation pennsylvanian a high pb bearing mineral content of samples zg6 2 and zg6 3 is likely of hydrothermal origin the no 6 coal is enriched in ga 44 8 g g se 8 2 g g sr 423 g g zr 234 g g rees 193 3 g g hg 0 35 g g pb 35 7 g g and th 17 8 g g gallium and th in the no 6 coal mainly occur in boehmite and the pb bearing selenide and sulfide minerals contribute not only to se and pb contents in the coal but also probably to hg content a high zr content is attributed to the presence of zircon and sr is related to goyazite the rees in the coal are supplied from the sediment source region and the rees leached from the adjacent partings by groundwater

miocene extension in the east range nevada a two stage history of normal faulting in the northern basin and range the east range in northwestern nevada is a large east tilted crustal block bounded by west dipping normal faults detailed mapping of tertiary stratigraphic units demonstrates a two phase history of faulting and extension the oldest sedimentary and volcanic rocks in the area record cumulative tilting of 30 45 e whereas younger olivine basalt fl ows indicate only a 15 20 e tilt since ca 17 13 ma cumulative fault slip during these two episodes caused a minimum of 40 extensional strain across the east range and quaternary fault scarps and seismic activity indicate that fault motion has continued to the present day apatite fi ssion track and u th he data presented here show that faulting began in the east range ca 17 15 ma coeval with middle miocene extension that occurred across much of the basin and range this phase of extension occurred contemporaneously with middle miocene volcanism related to the nearby northern nevada rifts suggesting a link between magmatism and extensional stresses in the crust that facilitated normal faulting in the east range younger fault slip although less well constrained began after 10 ma and is synchronous with the onset of low magnitude extension in many parts of northwestern nevada and eastern california these fi ndings imply that rather than migrating west across a discrete boundary late miocene extension in western nevada is a distinct younger period of faulting that is superimposed on the older middle miocene distribution of extended and unextended domains the partitioning of such middle miocene deformation may refl ect the infl uence of localized heterogeneities in crustal structure whereas the more broadly distributed late miocene extension may refl ect a stronger infl uence from regional plate boundary processes that began in the late miocene

geological controls on prediction of coalbed methane of no 3 coal seam in southern qinshui basin north china article i nfo in order to better understand the geological controls on coalbed methane cbm in southern qinshui basin sqb north china geological surveys and laboratory experiments including coal petrology analysis proximate analysis and methane adsorption desorption were conducted results show that the coals from the sqb contain 0 59 3 54 moisture 3 5 15 54 ash yield 73 62 88 92 fixed carbon and 2 14 4 04 hydrogen with c h ratios in the range of 19 96 36 25 the vitrinite reflectance ro m ranges from 1 95 to 3 49 the coals are composed of 18 5 97 4 vitrinite and 2 4 81 4 inertinite the geologic structures coal bearing strata and coal depositional environment were studied by both field geological research and laboratory tests a positive relationship is found between cbm content and basin hydrodynamics in which cbm easily concentrates in the groundwater stagnant zone because of the water pressure furthermore integrated geographical information system gis and analytical hierarchy fuzzy prediction method ahp were used to evaluate the cbm resources in the sqb the results show that the amount of cbm associated with the no 3 coal seam in the sqb is 3 62 10 11 m 3 t he cbm resource concentration gas in place per square kilometer in the sqb is in the range of 0 72 2 88 10 8 m 3 km 2 with an average of 1 21 10 8

history of the sevier orogenic wedge in terms of critical taper models northeast utah and southwest wyoming problems with applying critical taper models to ancient orogenic wedges are overcome in the late cretaceous late paleocene sevier orogenic wedge in utah and wyoming by a symptomatic approach in which wedge behavior is inferred from the time space distribution of thrust faulting erosion and synorogenic sediment accumulation in association with the orogenic wedge in turn the causes of wedge behavior are interpreted in terms of features that are known about the sevier wedge such as the locations of major decollements and the lithologic constituents of major thrust sheets from coniacian through late paleocene time 35 m y basement and cover rocks in the sevier wedge were shortened by 100 km in three major and one minor events an overall eastward progression of thrusting was punctuated by several episodes of out of sequence and hinterland vergent thrusting over the long term wedge taper was controlled by internal wedge strength initial taper and changes in the durability of the upper surface of the wedge and its internal lithostratigraphy critical taper was maintained by the offsetting effects of basement duplexing in the rear of the wedge and forward imbrication at the front of the wedge while the basal decollement was mainly in basement rocks the wedge was highly tapered and thrust spacing was relatively close 15 km beginning ca 75 ma the basal decollement ramped upward and eastward into weak cambrian shale and jurassic salt thrust spacing increased to 25 45 km and wedge taper decreased drastically the highly tapered rear part of the wedge carried strong basement rocks above moderately weak mylonitic and cataclastic decollements whereas the frontal lower taper part of the wedge carried sedimentary rocks above extremely weak salt and shale decollements through time internal strength of the wedge decreased as it incorporated an increasing proportion of sedimentary rocks the thrust belt was able to advance eastward in spite of its decreasing internal strength and decreasing taper because the basal decollement of the wedge also became weaker through time both by strain softening beneath the rear of the wedge and by propagating along extremely weak rocks beneath the front of the wedge provenance data from associated synorogenic conglomerates indicate that the durability of the upper surface of the wedge probably increased over the long term history of the sevier wedge as an increasing proportion of the erosional surface became occupied by resistant precambrian quartzite and basement rocks this would have had the effect of decreasing the rate of erosion through time and maintaining a steeper surface slope which would have helped the wedge to remain at critical to supercritical taper the sevier wedge also exhibits several shorter term 10 km and 3 was subjected to regional erosion marked by major unconformities that ultimately caught up with tectonic thickening and caused the wedge to stall this cyclicity is attributed to the need for wedges to become supercritical before they can propagate forward over large distances and a lag time between wedge thickening and uplift and wedge erosion erosion eventually catches up to the rate of uplift the wedge stalls and the locus of deformation shifts to the rear of the wedge in order to rebuild taper this analysis suggests that orogenic wedges continually deform and find a way to maintain taper sufficient to allow forward propagation as long as a sufficient push from the rear exists the actual taper value may change substantially through time as lithostratigraphy internal strength upper surface durability and presence absence of weak potential stress guides conspire to maintain a critical taper

minerals in bituminous coals of the sydney basin australia and the illinois basin u s a although other forms of inorganic components may be significant in lower rank coals the mineral matter in most bituminous coals is dominated by silicates carbonates sulphides phosphates and other crystalline mineral groups these may be present in various forms including thin bands and laminae intimately associated with the organic matter as well as lenticles nodules crystal aggregates and cell infillings all of which indicate approximately contemporaneous formation with the peat bed other minerals however occur as veins or cleat and fracture fillings indicating precipitation after most of the compaction and presumably after most of the rank advance ome of the penecontemporaneous mineral matter is of detrital origin representing epiclastic or pyroclastic particles washed or blown into the peat swamp other mineral matter however including much of the pyrite quartz and siderite as well as abundant well crystallized kaolinite appears to have been formed by precipitation processes either within the swamp waters or in the pores of the peat deposit pyrite largely formed by bacterial reduction of dissolved sulphate ions seems to be related in abundance to marine transgressions which allowed permeation of sea water into the swamp and through the peat bed beneath siderite appears to form in the absence of sulphate rich sea water probably from co2 released by organic decay the clay fraction of the noncoal rocks in many coal bearing sequences is typically dominated by illite or interstratified clay minerals with kaolinite chlorite and possibly montmorillonite also present to a variable though typically minor extent although perhaps modified by chemical reactions or ion exchange mechanisms in the peat swamp these clay minerals may also be present in the coal as well especially near the base of top of the seam the kaolinite in the noncoal rocks is usually poorly crystallized and typically a minor constituent but well crystallized kaolinite is characteristically present and often the dominant component in the mineral fraction of bituminous coal beds as well as in some of the lutites including underclays intimately associated with the seams a progressive upward gradation to a particularly kaolinite dominated mineral assemblage occurs in some seams of the sydney basin australia this gradation is thought to be due to either increased blockage of detrital contaminants as the swamp developed or to in situ chemical or biological leaching of the mineral fraction and reconstitution of the residues in the upper parts of the peat bed superimposition of such cycles is also noted within the seam in some instances suggesting repetition of several phases of this type during major peat accumulations

quantification of mineral matter in the argonne premium coals using interactive rietveld based x ray diffraction abstract the mineral matter in the eight reference north american coal samples of the argonne premium coal series has been investigated on a quantitative basis using x ray diffraction xrd techniques x ray diffraction data obtained from electronic low temperature oxygen plasma ash lta residues from ashes produced by heating the coals in air at 370 c and also from the raw coals themselves were evaluated using an interactive data processing system siroquant based on rietveld interpretation methods the results from the three types of material lta 370 c ash and raw coal were compared for each sample this allowed the components present in the raw coals in crystalline form to be recognised separately from mineral artifacts produced particularly in the low rank coals from interaction of organically associated elements ca s etc during the two ashing processes after the allowance for the production of any artifacts the quantitative mineral assemblages identified from xrd of the raw coals were found to be consistent even for coals having a relatively low ash percentage around 5 with the results obtained from the respective mineral concentrates prepared by the ashing methods the effects of heating the coal to 370 c could also be distinguished relative to the raw coal or the lta through changes in components such as pyrite and the clay minerals although some areas of uncertainty exist particularly with magnesium in the low rank coals the calculated chemical compositions of the coal ash derived from the mineral mixtures identified for each coal were also found to be consistent with the results of direct chemical analysis of the respective coal ash materials

high sr y magma petrogenesis and the link to porphyry mineralization as revealed by garnet bearing i type granodiorite porphyries of the middle cauca au cu belt colombia porphyry style cu au mo mineralization is widely associated with igneous suites with sr y 40 and low heavy rare earth element hree content this geochemical signature is commonly attributed to garnet or amphibole fractionation in the lower crust where mantle derived melts evolve into intermediate composition arc suites however the presence of a residuum related to mineralized porphyry systems where amphibole and garnet are stable is generally inferred from geochemistry and has nowhere been documented directly we here report on two occurrences of late miocene garnet bearing granodiorite porphyry at the tesorito au cu prospect in the quinchia district and el poma au cu prospect in the middle cauca au cu porphyry belt in colombia these rocks provide proof that garnet was stable in the lower crust at the time of porphyry mineralization at both studied sites garnet bearing i type granodiorite porphyries were intruded by intramineralization garnet free plagioclase phyric granodiorite porphyries that were cut by quartz and k feldspar veins and affected by biotite alteration garnet bearing porphyries predate intramineralization porphyries by 0 4 to 2 m y garnet occurs as unzoned grains commonly included in large plagioclase phenocrysts that in some cases also contain inclusions of igneous epidote the latter indicating pressures of 1 gpa for early crystallized phases large plagioclase phenocrysts exhibit two growth stages separated by a resorption boundary high al amphibole phenocrysts as well as titanite and magnetite formed after the first stage but prior to the second stage of plagioclase growth at pressures of ca 0 9 gpa whole rock geochemical compositions of garnet bearing porphyries are consistent with only limited garnet fractionation whereas some of the intramineralization porphyries have y 40 which is together with other trace element indicators taken as evidence for significant garnet fraction at depth during porphyry mineralization hree content of zircon in garnet bearing porphyries are higher than that of intramineralization porphyries which supports the interpretation that garnet fractionation in the lower crust was significant during the formation of the intramineralization porphyries the phase relationships and geochemical data reflect a geodynamic change from an environment that permitted rapid ascent of oxidized garnet bearing porphyries prior to au cu mineralization to a regime that favored melt evolution in the lower crust where garnet was a residual phase and at the same time allowed the formation of large mid to upper crustal magma chambers the latter are widely inferred to be essential for porphyry mineralization to occur

petrology of philippine geothermal systems and the application of alteration mineralogy to their assessment abstract philippine geothermal systems occur in the vicinity of large holocene calc alkaline volcanic complexes wells drilled in these areas encountered multiple intrusions the latest dikes are the subsurface manifestations of the youngest heat source commonly at least two hydrothermal regimes are juxtaposed in a single area with the latest being in equilibrium with the present temperature and chemical regime alteration by neutral ph water is pervasive and abundant a contact metamorphic aureole also occurs near intrusives alteration due to acid sulfate fluids is generally confined to permeable structures neutral ph alteration is divided into four zones on the basis of key clay minerals and two subzones are defined by calc silicates these are the smectite ambient to 180 c transition 180 230 c illite 230 320 c and biotite 270 340 c zones subzones are defined by epidote 250 340 c and amphibole 280 340 c the four main zones of acid alteration are kaolinite ambient to 120 c dickite kaolinite 120 200 c dickite pyrophyllite 200 250 c and pyrophyllite illite 230 320 c where relict high temperature alteration reaches the surface the area being drilled is usually the outflow zone of the present system these hydrothermal mineral assemblages are used 1 as geothermometers 2 to assist in determining the depth at which the production casing will be set during drilling 3 to estimate fluid ph and other chemical parameters 4 to predict possible corrosion and scaling tendencies of the fluids 5 as a measure of permeability and possible cold water influx into wells 6 as a guide to field hydrology and 7 to estimate roughly the thickness of the eroded overburden

origin and ore forming consequences of the advanced argillic alteration process in hypogene environments by magmatic gas contamination of meteoric fluids metasomatic effects have been thermodynamically computed for magma derived sulfur gases which may contaminate convecting meteoric fluids in the monzonite k silicate protore and are compared with natural assemblages in the butte district of montana the advanced argillic assemblage with covellite is produced in hypogene environments at 300 degrees c by sulfur metasomatism of protore only for a limited range of net sulfur valences essentially 1 to 2 placing limiting constraints on the possible ratios of so 2 and h 2 s gases a second important factor is the relative reaction rates of protore and contaminating sulfur gases contamination by sulfur gases is a third factor of importance a final factor is that a minimum negative net volume of reaction causes by wall rock dissolution and fracture enlargement the high permeability necessary for circulation of enormous quantities of hydrothermal fluids and vein growth characteristic of this extreme alteration facies modified journal abstract

isotope geochemistry of minerals in australian bituminous coal abstract several generations of carbonate minerals kaolinite and quartz are present in australian bituminous coals petrographic observations show that disseminated fine grained kaolinite and quartz are common in the coal on the basis of oxygen isotope ratios it appears that the disseminated kaolinite and siderite nodules were precipitated from permian pore water early in the deposition of peat at calculated temperatures of 16 to 32 c secondary cleat filling kaolinite at leichhardt colliery in the bowen basin has a constant 18o value of around 6 which is consistent with formation from mine water of the present isotopic composition at a temperature of 56 c lower temperatures are indicated for secondary kaolinitization in coals of the southern sydney basin detrital quartz grains and chemical quartz have similar isotopic compositions and therefore cannot be distinguished isotopically however the oxygen isotope ratio of disseminated fine grained silica is consistent with formation in the brown coal stage at a temperature of 52 c and depth of about 700 m secondary carbonates are not readily characterized in terms of isotopic criteria and are best recognized by their mode of occurrence the ability to distinguish between primary and secondary kaolinite appears to hold promise as a guide to prediction of outbursting conditions in underground coal mines

mineralogy and leaching characteristics of beneficiated coal products from santa catarina brazil abstract petrographic mineralogical and geochemical studies have been carried out on beneficiated coal products from mines and preparation plants in the santa catarina basin southern brazil to investigate the range of characteristics exhibited by the materials and the potential impact of their stockpiling and storage on the environment the coals contain varying proportions of vitrinite and inertinite macerals and have vitrinite reflectance values ranging from 0 44 to 1 38 with the exception of one material blended with peat from an external source they have relatively high percentages of ash 30 58 and mineral matter 36 66 the mineral matter consists mainly of clay minerals kaolinite illite and illite smectite together with 15 25 quartz up to 10 feldspar up to 5 calcite and or dolomite and up to 5 pyrite and around 1 anatase and or rutile bassanite is also present in low temperature ash derived from the coals mainly derived from interaction of ca and s associated with the organic matter jarosite is formed by pyrite oxidation in coals that have been exposed in stockpiles for extended periods most of the trace elements in most of the coals have higher concentrations than average values for world coals generally probably due to the relatively high mineral matter content a lower ash product representing a blend of coal and peat has similar to lower concentrations of most elements but higher concentrations of b ba be cd ge and mn which may be associated with the peat component interaction of relatively fresh coals with water in laboratory tests produces leachates with near neutral to mildly acid ph values but leaching of oxidized jarosite bearing coal produces a strongly acid leachate with higher concentrations of cd co cu ni and zn leachates derived from coals in which the pyrite has been oxidized during storage would thus be expected to have a more adverse environmental impact than leachates derived from coals in which such oxidation has not had an opportunity to develop

mineralogy and geochemistry of bobov dol coals bulgaria abstract the mineralogy elemental composition and modes of occurrence of 49 elements in nine composite samples of bobov dol high ash coals were studied by optical microscopy scanning and transmission electron microscopy x ray diffractometry and chemical analysis the major minerals were quartz kaolinite illite plagioclase and k feldspar and the minor minerals and phases were pyrite marcasite siderite calcite dolomite gypsum muscovite montmorillonite and volcanic glass the accessory minerals include a wide variety of minerals such as galena pyrrhotite magnetite hematite goethite chromite rutile anatase corundum gibbsite biotite chlorite zircon enstatite garnet jarosite alunite barite polyhalite aragonite ankerite witherite apatite halite and sylvite the modes of occurrence and some genetic peculiarities of the above mentioned minerals are described thirty three elements occurred in concentrations higher than the respective clarke values especially s rb nb hf zn cu pb mn ti and u the concentration trends and modes of occurrence of the trace elements are also discussed in decreasing order of significance the trace elements probably occur as element organic compounds as impurities in the mineral constituents as major components in the minerals as major and impurity components in the inorganic amorphous constituents and in the fluid constituents the bobov dol coals have undergone complex syngenetic diagenetic and epigenetic mineralization processes associated with hydrothermal and volcanic activities these processes were also accompanied by intensive tectonic movements and possibly by a later change from continental to marine sedimentation in the area after burial of the coal

geological controls on the quality of coals from the west shandong mining district eastern china abstract the basic coal quality parameters coal petrology mineralogy and geochemistry were investigated for coal seams 2 3 and 4 permian shanxi formation and 11 12 13 and 15 carboniferous taiyuan formation of the xinwen and feicheng coal fields in the west shandong mining district east china rank parameters indicate a high volatile c to b bituminous rank for the shandong coal coal from the zhaizhen and cha zhuang mines is characterised by high vitrinite and low middle inertinite and liptinite contents inertinite contents show an increase towards the top of the stratigraphic sequence from coal seams 15 13 and 11 to coal seams 4 and 2 this trend may be related to a stratigraphic trend characterised by the evolution of relatively more reducing conditions of the synsedimentary coal forming environment in the early taiyuan coals marine influenced lower delta plain to more oxidising paleoenvironments of the upper shanxi coal seams upper delta plain major mineral phases present in the shandong coal are quartz kaolinite pyrite and calcite traces of other primary minerals dolomite ankerite illite opal feldspars and marcasite and weathering products gypsum melanterite and hematite can be found in several coal seams the lower permian coal seams two to four have a lower mineral content 8 14 ash db than the upper carboniferous coal seams 15 37 ash db owing to the lower proportions of quartz and sulphide mineral the occurrence and distribution of the different minerals in the shandong coal indicates a paragenetic sequence characterised by an early syngenetic stage detrital minerals framboidal euhedral and massive cell filling pyrite ankerite neomorphic quartz and kaolinite middle and late syngenetic stages radial and fibrous marcasite aggregates massive pyrite and an epigenetic stage carbonates and sulphides as cleat filling a clear differentiation exists between the shanxi and the taiyuan coal seams based on the higher sulphide contents of the taiyuan coal 3 3 to 6 2 s db compared with the shanxi coal 0 4 to 0 8 s db this differentiation is related to marine influence on the depositional environment of coal seams 11 to 15 which has been reported by earlier studies vertical variations of the abundance of major and trace elements are discussed on the basis of this differentiation an epigenetic external enrichment of ge mo and u at the top of most of the coal seams is observed and major and trace element affinities are deduced for the west shandong coal

a fault controlled newly discovered eskisehir alpu coal basin in turkey its petrographical properties and depositional environment abstract recent findings suggest that turkey contains about 15 billion tons of coal within its borders a small proportion of it nw part is bituminous but the rest is sub bituminous and lignite coal about 80 of the coals are utilized in power generation the newly found coal field alpu basin contains about 1 3 billion tons of coal the coal basin is a fault controlled and deeply buried basin which is close to the industrial areas in turkey in the studied area there are two coal horizons in the middle miocene aged m2 unit the average mineable coal seam thickness is approximately 13 14 m in order to determine the coalification degree petrographic composition and depositional environment of the coals petrographic and xrd analyses were conducted on coal samples taken from three boreholes which were drilled by mta in the eskisehir alpu basin according to the astm classification the rank of the coals is sub bituminous alpu coals contain two prominent types of maceral assemblages either containing high amounts of funginites macrinites ulminite and gelinites or high amounts of liptinites associated with detrital huminites attrinite and densinites the first type exhibits rather more homogeneous features but the second has a more complex mixed appearance with detrital macerals intensive lineation laminations and considerably higher pyrite contents the alpu coals contain montmorillonite heulandite quartz pyrite gypsum kaolinite illite illite montmorillonite orthoclase and clay minerals which indicate variation in the ph conditions the tissue preservation index tpi and gelification index gi indicate a limnic environment the sample points are located between open marsh and clastic marsh areas on the tpi gi diagram this case indicates that the water table was variable during the coal formation

tectonics of the yellowstone hotspot wake in southwestern montana deposits off a neogene paleovalley provide a geologic datum in southwestern montana that brackets the age of faulting associated with the yellowstone hotspot ages of paleovalley deposits on top of the modern blacktail ruby tendoy and centennial ranges and in adjacent valleys range from 16 to 2 ma at least 2 km of offset has occurred since emplacement of the timber hill basalt 6 0 0 1 ma much may have occurred after deposition of the 2 0 ma huckleberry ridge tuff which is now found in isolated outcrops as far north as the ruby range gravel clasts within the paleovalley have a northern provenance whereas volcanic and volcaniclastic rocks were derived from the snake river plain to the south we propose that uplift associated with passage of the hotspot caused the drainage reversal

mineralogy of the volcanic influenced great northern coal seam in the sydney basin australia abstract the mineralogy of the individual coal plies and intra seam claystone bands in the great northern seam of the sydney basin has been evaluated using optical and scanning electron microscopy and quantitative x ray diffraction techniques the uppermost two claystone bands are tonsteins consisting mainly of well ordered kaolinite with graupen to vermicular textures idiomorphic crystals of k feldspar within these tonsteins may represent members of the anorthoclase sanidine series or a sodic sanidine and indicate an acid to intermediate volcanic ash input in contrast the lowermost parting was largely derived from epiclastic sediment admixed with minor volcanic material such as high temperature quartz and a different type of k feldspar component the mineral fraction of the coals especially in the middle and upper parts of the seam is dominated by authigenic kaolinite with a very low abundance of quartz apart from the tonsteins authigenic processes therefore appear to be the dominant mechanism of mineral matter formation authigenic k feldspar also occurs in the lower few metres of the seam with a variety of modes of occurrence including cell and cleat infillings cross cutting veins and thin laminae parallel to the organic matter and detrital clay bands a late syngenetic low temperature hydrothermal fluid injection process is suggested for formation of the feldspar veins the origin of the fluid is uncertain but is most likely associated with contemporaneous volcanic activity

thermal modelling of the laramide orogeny testing the flat slab subduction hypothesis abstract the laramide orogeny is the late cretaceous to palaeocene 80 55 ma orogenic event that gave rise to the rocky mountain fold and thrust belt in canada the laramide block uplifts in the usa and the sierra madre oriental fold and thrust belt in mexico the leading model for driving laramide orogenesis in the usa is flat slab subduction whereby stress coupling of a subhorizontal oceanic slab to the upper plate transmitted stresses eastwards producing basement cored block uplifts and arc magmatism in the foreland the thermal models presented here indicate that arc magma generation at significant distances inboard of the trench 600 km during flat slab subduction is problematic this conclusion is consistent with the coincidence of volcanic gaps and flat slab subduction at modern convergent margins lawsonite eclogite xenoliths erupted through the colorado plateau in oligocene time are inferred to originate from the subducted farallon slab and indicate that the laramide flat slab subduction zone was characterised by a cold thermal regime thermal modelling indicates that this regime can be produced by flat slab subduction of old 50 myr oceanic lithosphere at high convergence rates in the canadian and mexican portions of the laramide orogen the coeval development of a magmatic arc within 300 km of the trench refutes the existence of flat slab subduction in these regions it is proposed that subduction of an oceanic plateau aseismic ridge may have overcome the negative buoyancy inherent in old oceanic lithosphere and resulted in a spatially restricted zone of flat slab subduction in the usa these findings cast doubt on the flat slab model as a primary means of driving laramide orogenesis along its entire length and instead point to the need for an alternative mechanism for cordilleran wide laramide orogenesis

structural geologic evolution of the butte district montana the butte district contains two porphyry cu mo deposits and the younger zoned main stage base metal lode deposits that formed in the period from 66 to 62 ma synchronous with laramide compressional thrust faulting and folding in southwest montana new geologic mapping of the butte district reveals three distinct episodes of deformation 1 gentle 20 10 ne tilting produced during laramide compressional deformation uplift and exhumation during and after ore formation in the late cretaceous to paleocene 66 53 ma 2 moderate 10 50 nw tilting of eocene age produced by ne striking normal faults that are limited to the northwest part of the district and synchronous with the eruption of the lowland creek volcanics and 3 miocene to present gentle 15 ese tilting in the hanging walls of the continental east ridge and rocker normal faults stratigraphic relationships isotopic ages hornblende barometry and fluid inclusion data indicate that exposures of the butte granite which hosts mineralization crystallized at 6 to 9 km depth and that early porphyry cu mo deposits formed at similar depths of 5 to 9 km a period of rapid uplift and erosion removed about 7 km of rock from above the ore deposit between 66 to 64 ma and 53 ma but was mostly completed by 59 ma estimated exhumation rates range from 0 5 to 2 mm yr and uplift was likely most rapid between 63 5 and 62 ma during main stage mineralization which occurred at depths of 2 to 6 km the butte granite and boulder batholith were emplaced at 79 to 76 ma into thrust fault ramps which later became inactive near butte as laramide crustal shortening moved eastward in the helena salient the accelerated period of uplift and unroofing is attributed to renewed deformation along the montana disturbed belt south of butte that uplifted the south end of the boulder batholith and produced 20 of gentle ne tilting episode i in the district the exhumation history of the deposit is therefore broadly contemporaneous with ore formation and is consistent with the general transition from lithostatic to hydrostatic conditions that is evident from the telescoping of early porphyry cu mo ores cut by the main stage lode veins within a 5 m y period the laramide compressional regime near butte evolved into an extensional environment characterized by normal faulting the normal faults were synchronous with eruption of the 53 to 48 ma lowland creek volcanics which directly overlie the main stage veins in the northwest part of the district structural reconstruction of the district at the time of mineralization produces orientations of quartz porphyry dikes porphyry cu mo veinlets main stage veins and alteration zonal patterns that are steeply dipping and symmetrical similar to observations from other upright or restored porphyry copper deposits early porphyry cu mo veins and dikes are oriented e w and likely originated as tensile hydrofractures above a ductile magma carapace during laramide shortening additionally during the laramide compressional phase two conjugate fault systems occupied by main stage veins are normal oblique slip faults that record minor e w and vertical shortening and n s extension these normal faults with minor offset likely resulted from brittle failure caused by doming above a volatile rich and buoyant granitic magma chamber and cupola at depth the structural evolution of the butte district therefore reflects the interaction of a far field compressive stress regime with local buoyant magmatic forces

smectite and illite smectite mixed layer clay minerals in the ashibetsu coals abstract smectite k smectite and illite smectite i s mixed layer minerals are found as expandable clay minerals in the paleogene coal seams of the ashibetsu coal mine in the ishikari coal field hokkaido japan as k smectite often exists in tuff tuffaceous shale and coal near tuff and only occasionally in shale the k smectite is simply thought to represent detrital input from tuff smectite often exists in the coals near intercalated tuff roof tuff and tuffaceous shale beds but is not found in these sediments although many tuffs contain both k smectite and i s mixed layer clay minerals the smectite coexists with only k smectite in many coals and the coal in which smectite occurs never has both of the other minerals from these relationships it may be inferred that smectite was formed in the coal mainly from the i s mixed layer and only partly from k smectite the i s mixed layer clay found in the tuff and tuffaceous shale is never accompanied by illite but the i s mixed layer clay in the shale is almost always accompanied by illite i s mixed layer clay without illite exists in some coals near tuff and i s mixed layer clay with illite is often found in the other coals these relationships mean that the i s mixed layer clay in the coal is also of detrital origin derived from the same sources as both the tuff and the shale beds the i s mixed layer clays plotted using watanabe s 1981 1988 identification graph show a pattern consistent with illitization by diagenesis the illitization appears to be related to the burial depth and or coal rank it is also shown that the mixed layer clays in the shales have higher illite layer ratios than those in the tuffs the tuffaceous shales and the coals without illite from this evidence it appears that the composition of i s mixed layer clay depends mainly on processes associated with the source of the original sediment input

use of mineralogical analysis in geotechnical assessment of rock strata for coal mining abstract the fundamental geotechnical properties of sedimentary rocks from the coal bearing sydney basin of new south wales australia including density porosity water absorption and moisture content as well as compressive strength have been related to the mineralogy of the materials as determined by quantitative x ray diffraction of powdered rock samples and processing by the rietveld based siroquant technique the results show for example that the overall proportions of clay minerals in the rocks as well as the types of clay minerals present affect properties such as water absorption and moisture content the presence of clay minerals also adds to the dry strength of silica cemented quartz sandstones however the strength of finer grained mudrocks is inversely related to the total percentage of clay minerals correlations have been established between the deterioration or slaking behaviour of mudrocks in water and their clay mineral content based on either simple immersion tests or on more sophisticated slake durability index determinations these relationships may be of significance in understanding the longer term behaviour of rock strata when exposed in different types of mining operations the propensity of different rocks to ignite methane in underground mines by frictional effects has also been shown to depend on the mineralogy of the rock materials whether determined by point counting of thin sections or by rietveld based xrd analysis abundant quartz feldspar and rock fragments in sandstones for example increase the likelihood of frictional ignitions whereas clay minerals and especially carbonates in the rock reduce the frictional ignition potential pyrite in the rocks if present also increases the ignition risk pyrite undergoes exothermic oxidation at high temperatures whereas other minerals respond by simple heating due to rock on rock or pick on rock friction processes

petrology of the yerington batholith nevada evidence for evolution of porphyry copper ore fluids the jurassic yerington batholith western nevada is a composite pluton that contains several centers of porphyry copper mineralization and is exposed in structural cross section at paleodepths ranging from 0 to 8 km within these exposures the mcleod hill quartz monzodiorite bear quartz monzonite and luhr hill granite form successive intrusions that are in turn volumetrically smaller approximately 75 19 and 6 vol respectively more deeply emplaced tops at 65 km 3 luhr hill granite the low cu content approximately 10 ppm of the granite would allow extraction of approximately 50 ppm cu from it during crystallization these data suggest an orthomagmatic model in which both high and low density saline aqueous fluids formed during exsolution of water from the crystallizing luhr hill granite and from which salts cu fe and s strongly partitioned into the high density ore fluid low density fluids may have risen from the magma as a vapor plume mineralization occurred when fluid overpressures caused fracturing of wall rock and upward intrusion of granite porphyry dikes and high density saline ore fluids both the f sub o 2 path during subsolidus cooling and the deposition of most s as chalcopyrite pyrite in ore suggest that reduction of magmatic s to sulfide may have been a mechanism for oxidation of magmatic ferromagnesian silicate and fe ti oxide minerals