late quaternary environmental changes in the pearl river mouth region china abstract this study presents findings concerning late quaternary environmental changes in the pearl river mouth region china based on the study of over 300 boreholes out of these 35 boreholes are selected for the reconstruction of transects across the deltaic plain and estuary 39 radiocarbon dates obtained from these boreholes are used to help define the chronology of stratigraphic units present including two terrestrial units t1 and t2 and two marine units m1 and m2 diatom assemblages are studied in 6 boreholes revealing similarities and differences between the two marine units before the area was inundated by the last interglacial sea mis 5 an older terrestrial unit of sand and gravel t2 was laid down in a number of palaeo valleys during the last interglacial period an older marine unit of silt and clay m2 was laid down which was subsequently subaerially exposed when sea level regressed during the last glacial period mis 4 2 causing the uppermost section to be weathered during the same period a younger terrestrial unit of sand and gravel t1 was deposited along palaeo river channels around the early holocene before 8 2 cal ka bp the postglacial rise in sea level initiated a new phase of sedimentation in the outer part of the estuary characterised by the high percentages of marine diatoms in the sediments in the early holocene strong monsoon freshwater discharge resulted in sedimentation of a fine sand layer in the inner part of the estuary after 8 2 cal ka bp rapid rises in sea level caused widespread marine inundation and sedimentation the diatom data suggest that the relative sea level associated with the m2 and m1 units were both at similar levels because the m2 unit is typically recorded at altitudes of 15 m and 20 m below the present sea level this is likely to be a result of long term subsidence although numerical dating of the pre m1 units has not been made in the present study the chronology of these units can be inferred from uranium series ages and optically stimulated luminescence dating obtained from the adjacent coastal waters of hong kong the t1 unit has yielded ages of about 30 0 cal ka bp while the m2 unit has yielded ages about 130 0 cal ka bp confirming their mis 4 2 and mis 5 ages respectively

optically stimulated luminescence age controls on late pleistocene and holocene coastal lithosomes north carolina usa luminescence ages from a variety of coastal features on the north carolina coastal plain provide age control for shoreline formation and relative sea level position during the late pleistocene a series of paleoshoreline ridges dating to marine isotope stage mis 5a and mis 3 have been defined the kitty hawk beach ridges on the modern outer banks yield ages of 3 to 2 ka oxygen isotope data are used to place these deposits in the context of global climate and sea level change the occurrence of mis 5a and mis 3 shorelines suggests that glacio isostatic adjustment gia of the study area is large ca 22 to 26 m as suggested and modeled by other workers and or mis 3 sea level was briefly higher than suggested by some coral reef studies correcting the shoreline elevations for gia brings their elevation in line with other sea level indicators the age of the kitty hawk beach ridges places the holocene shoreline well west of its present location at ca 3 to 2 ka the age of shoreline progradation is consistent with the ages of other beach ridge complexes in the southeast usa suggesting some regionally contemporaneous forcing mechanism

late quaternary history of the marmara sea and black sea from high resolution seismic and gravity core studies abstract lithologic and multi proxy paleoenvironmental data from 21 dated cores have been used to define three allostratigraphic units allounits within the late quaternary successions of the marmara sea and black sea allounits are bounded by unconformities and their correlative conformities in both regions allounit a extends from the seafloor downward to a 12 11 ka sequence boundary which is a major shelf crossing unconformity in water depths less than 100 110 m in deep basins of the marmara sea the lower part of allounit a designated subunit a2 is a laminated sapropel m1 on the shelf subunit a2 consists of backstepping delta lobes and early transgressive barrier islands and sand sheets allounit b has only been recovered in marmara sea cores collected at water depths greater than 90 m and represents basinal or prodeltaic deposition during the 23 12 ka late pleistocene lowstand during the last glacial maximum the shelves surrounding the marmara sea were subaerially exposed and deltas of allounit b accumulated along the present day shelf edge following the post glacial rise of global sea level to 75 m at 12 ka the marmara sea quickly became inundated and thereafter rose in synchroneity with the mediterranean by 10 ka the black sea rose to start spilling into the marmara sea leading to establishment of a brackish water lid that has persisted to the modern day the strongest black sea outflow began at 10 ka and persisted to 6 ka promoting the accumulation of sapropel m1 in the deep marmara sea and progradation of an overflow delta just south of the exit from the bosphorus strait allounit c is a laminated sapropel m2 in basinal cores dated at 30 23 ka like m1 it is believed that m2 accumulated during a period of increased brackish water input into the marmara sea mainly from the black sea in the black sea wave erosion kept the shelf stripped of unconsolidated sediments during the falling sea level associated with the last glaciation and subsequent early stages of the post glacial holocene transgression this erosion created a major unconformity shelf edge deltas of allounit b received their sediment during the last lowstand from small rivers that likely coalesced into a single system toward the shelf edge at modern water depths of 100 to 110 m these deltas were active until 11 10 5 ka subsequently sea level in the black sea rose to 40 m by 10 ka and a set of backstepping barrier islands developed on the shelf as part of the associated transgressive systems tract once water level reached 40 m continued sea level rise stalled until 9 ka as the black sea began to spill across the bosphorus strait into the marmara sea

amino acid racemization geochronology of reworked quaternary mollusks on u s atlantic coast beaches implications for chronostratigraphy taphonomy and coastal sediment transport approximately 200 shells primarily mercenaria from 21 beach sites between new jersey and florida have been analyzed for the extent of racemization epimerization of their fossilized amino acids the greatest concentration of sites is in north carolina in regions least affected by human modification of natural beach sediment transport processes these results can be used to estimate the frequency of age mixing of pleistocene shell material in holocene depositional environments selected shells have also been dated by 14c conventional and or ams to provide direct calibration of the amino acid epimerization ratios shell taphonomic characteristics particularly color can be qualitatively related to apparent ages data for shell fragmentation combined with amino acid age estimates provide insights into probable transport distances of reworked shells shells with apparent pleistocene ages have epimerization values equivalent to those seen in onshore exposures of pleistocene coastal units amino acid epimerization measurements are a comparatively rapid and inexpensive chronologic tool for use in taphonomic and sediment shell transport studies paired amino acid 14c analyses on single shells provide insights into geochemical alteration of shells and permit modelling of the residence time of shells on beaches greater numbers of analyses at each site are needed before statistically valid estimates of age mixing can be obtained but the apparent distribution of pleistocene shells on atlantic coast beaches appears to be related to the distribution of pleistocene units in the shoreface and inner shelf and the thickness of holocene sedimentary cover in specific areas these observations provide useful criteria for the evaluation of possible age mixing of shells collected at outcrops of pleistocene units in the coastal plain

magnetic susceptibility study of late quaternary inner continental shelf sediments in the hong kong sar china abstract four cores of inner continental shelf sediment from the hong kong special administrative region sar have been measured for magnetic susceptibility in all the cores the upper part of marine isotope stage mis 1 down to about 3 m below seabed show abruptly elevated but highly variable levels of magnetic susceptibility attributable mainly to shipping contamination over the past 160 years the uncontaminated lower mis 1 deposits show a consistently low magnetic susceptibility above a sharp increase at the holocene pleistocene boundary this increase is accounted for by the presence of eroded palaeosol fragments enriched in iron oxides and hydroxides acid sulphate soil development during mis 2 4 on the sub aerially exposed inner continental shelf covered by mis 5 deposits is responsible for the formation of palaeosols the timing is therefore the opposite of palaeosols within terrestrial loess sequences in that they were formed during the last glacial period seventeen uncorrected conventional and accelerator mass spectrometry ams radiocarbon dates of mud and shell samples from the cores indicated that the palaeosols were formed before about 9130 yr bp to 19 430 yr bp

thermal infrared analysis of weathered granitic rock compositions in the sacaton mountains arizona implications for petrologic classifications from thermal infrared remote sensing data 1 critical to spectral interpretations of geologic surfaces on the earth and mars is an understanding of the relationship between the composition of weathered rock surfaces and whole rock mineralogy in this study thermal infrared spectroscopic and remote sensing analyses were used to determine the composition of weathered granitoid rock surfaces in the sacaton mountains arizona a linear spectral deconvolution approach was employed to determine the mineralogies of naturally exposed weathered surfaces and artificially exposed fresh rock surfaces deconvolution results from fresh rock surfaces yield similar bulk mineralogy to results from point counting of rock slabs and thin sections deconvolution of weathered rock spectra indicate that compared to fresh samples weathered surfaces are deficient in plagioclase feldspar and are enriched in clay minerals the differential weathering of feldspar minerals impacts the interpretation of whole rock mineralogy and the spectral classification of bedrock geology which for plutonic rocks is dependent on the relative proportions of different feldspars deconvolutions of multispectral remote sensing or laboratory data show a deficiency of total feldspar in the weathered rock units but lack sufficient spectral resolution for the discrimination between different feldspars these results demonstrate that the differential breakdown and removal of primary minerals in rock surfaces due to weathering can affect the interpreted rock petrology from remote sensing studies the relationships observed in our granitic samples could be applied to any rock type and may be important to consider for remote sensing of mars

potassic and sodic metasomatism in the southern province of the canadian shield evidence from the paleoproterozoic serpent formation huronian supergroup canada abstract major element geochemistry petrographic observations and microprobe analyses of the paleoproterozoic serpent formation huronian supergroup canada suggest that these strata experienced both potassium and sodium metasomatism major element data plotted in al2o3 cao na2o k2o compositional space form an array nearly identical to data from sub huronian paleosols reported elsewhere suggesting that serpent fluvial systems captured materials from entire weathering profiles potassium metasomatism was concentrated in shales and represents the illitization of kaolinite which is a residual product of plagioclase weathering sodium metasomatism principally affected silt and sand sized particles microprobe analyses of plagioclase grains indicate that they are nearly pure albite ab96 corresponding whole rock major element data plot in bulk albite space on an al2o3 k2o cao na2o ternary diagram whereas basement rocks plot in bulk andesine and oligoclase space end member compositions and the absence of luminescence when bombarded with an electron beam indicate that the albites are of secondary origin extremely pure albite cements ab99 commonly fringe detrital grains there has been little replacement of detrital k feldspars despite the complete albitization of plagioclase grains the timing of metasomatism at least the last stage is constrained to the period between 1700 and 1750 ma based on geochronologic data reported elsewhere when the southern province of the canadian shield experienced considerable felsic plutonism possibly related to arc collision this plutonism may have resulted in the heating of deep basinal brines stresses associated with orogenic build up or gravity driven groundwater circulation working in concert with the plutonism expelled these brines through the serpent formation and the entire huronian supergroup thoroughly metasomatizing the region such processes associated with collisional tectonics are akin to the development of mississippi valley type pb zn mineralization in the mid continent of the united states

the last interglacial shoreline in australia a review abstract marginal marine strata of last interglacial age occur in a range of morphostratigraphic settings around the australian coastline the lithofacies are similar to their holocene equivalents but are partly lithified elevated and laterally displaced inland uranium series ages for corals and molluscs from widely separated localities around the australian coastline are generally in accord with the accepted age for oxygen isotope substage 5e 125 000 10 000 bp the value generally accepted for the last interglacial maximum amino acid racemisation has principally been applied to correlation of sequences with benchmark sites dated by the uranium series method elevations of preserved last interglacial shorelines do not support the notion that australia is a stable continent significant neotectonic anomalies include cape cuvier 10 5 m fleurieu peninsula 6 m the coorong coastal plain 10 m and tasmania 32 m each indicating contrasting degrees of local uplift the tasmanian sequences are the highest occurrence on the australian continent and have been attributed to uplift as a result of mantle hotspot processes with the exception of these tectonically uplifted sites the height of the last interglacial sea surface around the australian coastline is consistently below the 6 m level globally attributed to this high sea level stand in australia the most consistent datum is from western eyre peninsula where a level 2 m above present mean sea level is ubiquitous the more southerly limit of coral growth and wider distribution of subtropical molluscan fauna are in accordance with warmer ocean waters during substage 5e approximately 2 c the extent of racemisation in molluscan fossils from southern australia also excludes the possibility of a more equable latitudinal distribution of mat during substage 5e

radiocarbon dating and the reconstruction of late quaternary sea level changes in hong kong abstract radiocarbon dating is used widely for the reconstruction of late quaternary sea level changes in the present study eight case studies in hong kong have been chosen to highlight the difficulty in obtaining reliable radiocarbon dates pre holocene radiocarbon dates exceeding about 8100 yr bp have been found to show a young age bias a shell sample dated by two separate radiocarbon laboratories gave last interstadial ages differing by almost 9500 years while an oxygen isotope stage 5e age was obtained using uranium series dating other evidence including stratigraphy have shown that only the last interglacial age is acceptable the young age bias is attributed mainly to the post depositional introduction of young carbon into the sample for the reconstruction of sea level changes it is essential to select samples immediately above of the base of the holocene transgressive unit in offshore boreholes and excavations to satisfy the criteria of rapid burial these samples should preferably include mud plant matter and shells to facilitate interpretation furthermore as many samples as possible from a range of water depth down to about 130 m below the present sea level should be dated to reduce error introduced by counting statistics so the true signal of sea level changes can be reflected

interior channels in martian valley networks discharge and runoff production the highland valley networks are perhaps the most compelling evidence for widespread fluvial activity on mars 3 5 ga however determining the hydrology of these features has been difficult owing to poor image resolution and the lack of available topographic data new orbital imaging reveals 21 late stage channels within valley networks which we use to estimate formative discharges and to evaluate water supply mechanisms we find that channel width and associated formative discharge are comparable to terrestrial valley networks of similar area and relief for 15 narrow channels in basin filling networks likely episodic runoff production rates up to centimeters per day and first order formative discharges of 300 3000 m 3 s are similar to terrestrial floods supplied by precipitation geothermal melting of ground ice would produce discharges 100 times smaller per unit area and would require pulsed outbursts to form the channels in four large valleys with few tributaries wider channels may represent large subsurface outflows or paleolake overflows as these four channels originate at breached basin divides and or near source regions for the catastrophic outflow channels

modelling sea level data from china and malay thailand to estimate holocene ice volume equivalent sea level change abstract this study presents a new model of holocene ice volume equivalent sea level esl extending a previously published global ice sheet model bassett et al 2005 which was unconstrained from 10 kyr bp to present this new model was developed by comparing relative sea level rsl predictions from a glacial isostatic adjustment gia model to a suite of holocene sea level index points from china and malay thailand three consistent data model misfits were found using the bassett et al 2005 model an over prediction in the height of maximum sea level the timing of this maximum and the temporal variation of sea level from the time of the highstand to present the data model misfits were examined for a large suite of esl scenarios and a range of earth model parameters to determine an optimum model of holocene esl this model is characterised by a slowdown in melting at 7 kyr bp associated with the final deglaciation of the laurentide ice sheet followed by a continued rise in esl until 1 kyr bp of 5 8 m associated with melting from the antarctic ice sheet it was not possible to identify an earth viscosity model that provided good fits for both regions with the china data preferring viscosity values in the upper mantle of less than 1 5 10 20 pa s and the malay thailand data preferring greater values we suggest that this inference of a very weak upper mantle for the china data originates from the nearby subduction zone and hainan plume the low viscosity values may also account for the lack of a well defined highstand at the china sites

effect of precursor mineralogy on the thermal infrared emission spectra of hematite application to martian hematite mineralization 1 observations from the thermal emission spectrometer tes instrument aboard the mars global surveyor mgs spacecraft led to the discovery of two isolated deposits of gray crystalline hematite located in meridiani planum and aram chaos and several smaller deposits in valles marineris several pathways for formation of these hematite deposits have been proposed involving both aqueous and nonaqueous processes this work uses the precise shape and position of spectral features in the martian hematite thermal emission spectrum to constrain hematite formation pathways thermal infrared emission spectra x ray powder diffraction patterns mossbauer spectra and transmission electron microscope tem photomicrographs were obtained for synthetic and natural hematite samples derived by 1 dehydroxylation of fine grained goethite and 2 oxidation of magnetite collectively the instrumental analyses show that the mineralogical composition and crystal morphology of precursor samples and the time and temperature conditions under which decomposition to hematite occur determine the crystallinity and crystal morphology of the hematite product comparison of laboratory and mgs tes spectra shows that the martian hematite spectra correspond closely with a synthetic hematite sample derived by pseudomorphic and topotactic dehydroxylation of goethite at 300 c spectra of goethite precursor samples dehydroxylated at higher temperatures provide increasingly poor fits spectra of hematite samples derived by high temperature thermal oxidation of magnetite are also poorer fits to the martian hematite spectrum thermal emission spectra of goethites heated at lower temperatures are characterized by the spectral signatures of both hematite and goethite and are not consistent with the martian spectra the characteristic that distinguishes the synthetic hematite sample with the mars like spectral signature from the other synthetic hematite samples is the high proportion of crystal surfaces that are crystallographic 001 faces c faces for the former but not the latter the high proportion of 001 face area results because the largest surface of the lath shaped hematite particles is the 001 face as determined by tem thus a possible formation pathway for hematite in meridiani planum aram chaos and valles marineris is precipitation of goethite from aqueous solutions as lath shaped crystals possibly as a stain cement and or massive deposit followed by pseudomorphic and topotactic dehydroxylation to hematite at temperatures below 300 c

pleistocene coastal stratigraphy sea level highstands and neotectonism of the southern australian passive continental margin a review located in a tectonically stable intraplate setting and in the far field of former ice sheets the southern australian passive continental margin represents a globally important region for quantifying sea level during pleistocene highstands the stratigraphical record of the southern australian margin is dominated by geographically extensive coastal barrier estuarine and peritidal landforms of bioclastic temperate carbonate affinity a function of regional aridity siliciclastic successions dominate the eastern australian coastline despite the generally high level of tectonic stability regional contrasts are evident in the elevation of pleistocene shoreline deposits that largely relate to pre quaternary geotectonic setting the most complete record of pleistocene highstand deposits occurs in the murray basin coorong coastal plain region and indicates that interglacial sea level highstands for at least the past 11 interglacials did not deviate by more than 6 m from present sea level the pleistocene marginal marine record of southern australia is dominantly represented by coastal successions deposited during marine oxygen isotope stages 5e and 7 equating with relative sea level maxima of 2 6 m and greater than 1 m above present sea level apsl respectively intertidal facies of late pleistocene interstadial successions rarely occur above present sea level the most reliable record of glacio eustatic ice equivalent sea level is registered on coastlines developed on stable precambrian cratons such as the gawler craton eyre peninsula where a consistent elevation of 2 m apsl is registered for over 500 km for the last interglacial shoreline 125 ka copyright 2002 john wiley sons ltd

clay minerals in delta deposits and organic preservation potential on mars clay rich sedimentary deposits are often sites of organic matter preservation and have therefore been sought in mars exploration however regional deposits of hydrous minerals including phyllosilicates and sulphates are not typically associated with valley networks and layered sediments that provide geomorphic evidence of surface water transport on early mars the compact reconnaissance imaging spectrometer for mars crism has recently identified phyllosilicates within three lake basins with fans or deltas that indicate sustained sediment deposition eberswalde crater holden crater and jezero crater here we use high resolution data from the mars reconnaissance orbiter mro to identify clay rich fluvial lacustrine sediments within jezero crater which has a diameter of 45 km the crater is an open lake basin on mars with sedimentary deposits of hydrous minerals sourced from a smectite rich catchment in the nili fossae region we find that the two deltas and the lowest observed stratigraphic layer within the crater host iron magnesium smectite clay jezero crater holds sediments that record multiple episodes of aqueous activity on early mars we suggest that this depositional setting and the smectite mineralogy make these deltaic deposits well suited for the sequestration and preservation of organic material

high silica deposits of an aqueous origin in western hellas basin mars 1 data from the thermal emission spectrometer and the thermal emission imaging system have been used to identify isolated high silica surfaces in western hellas basin deconvolution results indicate that the surfaces are composed of nearly 80 high silica phases amorphous silica phyllosilicates or zeolites the deposits may be derived from alcoves in the terrain immediately to the north the high silica deposits are an additional indicator of a variety of past aqueous processes on mars

thermal infrared spectroscopy on feldspars successes limitations and their implications for remote sensing abstract minerals of the feldspar group are the most common on earth feldspars are economically important in two ways either as industrial minerals or as a vector to ore for mineral deposits in order to use feldspars for classifying rock compositions or metasomatic conditions during rock alteration events there is a need for analytical methods to identify and classify feldspars traditionally feldspar composition and structure have been investigated using methods such as optical microscopy electron microprobe analysis empa cathodoluminescence and x ray diffraction xrd analysis in this paper infrared techniques 0 7 25 m are reviewed in detail and investigated in how far some of the traditional analytical methods can be replaced by infrared spectroscopy successes as well as limitations of infrared approaches are highlighted and existing work is scrutinized in terms of its applicability to remote sensing techniques even though numerous studies on mid infrared mir spectroscopy of feldspars exist their results often cannot be directly related to remote sensing applications examples are the effects of feldspar twinning exsolution textures and structural state on infrared spectra the applicability of the results to emission remote sensing requires further research it has been shown that linear unmixing of laboratory infrared spectra of rocks works fairly well detection limits for feldspar are around 5 and plagioclase composition can be determined within error margins of 4 anorthite component infrared spectroscopy can however not detect compositional zonation or different generations of feldspars infrared spectra represent the current average plagioclase and average alkali feldspar composition in the sample with several new airborne instruments under development it is opportune to focus upcoming research efforts on developing standardized processing techniques and spectral feldspar indices for thermal infrared imagery commercially interesting products include numbers of feldspars species plagioclase and alkali feldspar composition their structural state and relative or semi quantitative abundance in the rocks

sea level history 45 000 to 30 000 yr b p inferred from benthic foraminifera gulf st vincent south australia surficial sediments of gulf st vincent south australia are predominantly bioclastic cool temperate carbonates benthic foraminifera are abundant and distribution of species is closely related to water depth for example massilina milletti is most common at depths ca 40 m while discorbis dimidiatus is characteristics of shallow subtidal environments elphidium crispum a shallow water species and e macelliforme favoring deeper water provide a useful numerical ratio their logarithmic relative abundance in the sediment size fraction 0 50 0 25 mm correlates strongly with water depth vibrocores sv 4 and sv 5 recovered undisturbed sections of quaternary strata from the deepest part ca 40 m of gulf st vincent amino acid racemization and radiocarbon age determinations show that late pleistocene sections of the cores were deposited over the time ca 45 000 to 30 000 yr b p species of fossil foraminifera recovered from these sections are mostly extant in modern gulf st vincent thus allowing paleoecological inferences of late pleistocene sea levels these inferred sea level maxima can be correlated with those determined from study of huon peninsula coral reef terraces initial estimates of tectonically corrected sea levels for transgressions in gulf st vincent at 40 000 and 31 000 yr b p are 22 5 m and 22 m respectively the intervening regression lowered sea level to 28 m

holocene sea level highstand and its implications for the vertical stability of panglao island southwest bohol philippines abstract emerged tidal notches in panglao island southwest bohol central philippines were used to investigate relative sea level changes during the holocene the elevation and profile of a laterally continuous notch were surveyed at 22 sites around panglao island the tidal notch documents higher than present mean sea level pmsl consistent with regional field observations and predictions for mid holocene time the reconstructed paleo shoreline elevations range from 0 to 1 6 m above pmsl exhibiting a general increase to the northeast the more protected part of the coast this lateral variation in the holocene paleo mean sea level msl along with changes in notch depth and profile suggests tilting of the island best explained by differential land movement last interglacial msl estimates by previous workers also show tilting to the southwest moreover the holocene notch data suggest segmentation of the island into several blocks that tilt consistently to the southwest suggesting the presence of faults lineations in aerial photographs trending northeast southwest confirm the presence of these faults these data indicate differential land movements during the holocene and late pleistocene calculated rates of uplift are 0 3 and 0 06 mm yr for the holocene and for the late pleistocene respectively these values relative to the high uplift rates from tectonically active regions imply that panglao is relatively vertically stable after accounting for tectonic tilting mid holocene sea level is estimated at approximately 0 3 0 6 m

amino acid chronostratigraphy of late quaternary coral reefs huon peninsula new guinea and the great barrier reef australia d alloisoleucine l isoleucine d l ratios were measured in tridacna gigas the giant clam whose ages were calibrated against radiometrically dated coral reef terraces from new guinea and storm ridges on coral islands from the great barrier reef the results of 52 samples show several distinct intervals encompassing a fast epimerization phase at a rate of 0 077 ka for the first 8 ka a transitional interval for the next 60 ka during which epimerization evolves at the rate of 0 006 ka and the final phase between 60 and 185 ka when d l ratios attain quasi equilibrium 1 30 at an average rate of 0 003 ka the demonstrated relation between the d l ratios and the radiometric ages is useful for estimating ages of undated or insufficiently dated terraces a comparison of the new guinea curve and other less completely dated curves from elsewhere demonstrates the effect of sedimentary temperature on the rate of epimerization through time refinements of the d l reaction among coral reef terraces coupled with a better definition of the kinetic model presented here would improve our knowledge of the temperature history and the chrono stratigraphy of quaternary coral reefs

surface mineralogy of martian low albedo regions from mgs tes data implications for upper crustal evolution and surface alteration 1 mars global surveyor thermal emission spectrometer mgs tes data are used to derive the modal mineralogy of spectrally distinct martian low albedo regions and to identify spatial trends in mineralogic assemblages results from this work are consistent with the major results of previous spectroscopic studies 1 plagioclase and clinopyroxene are the dominant minerals of most southern highlands regions 2 the northern plains exhibit the lowest pyroxene abundance within martian low albedo regions and 3 the highest concentrations of high silica phase s are found in the northern plains solis planum and a few southern high latitude regions low albedo regions may be classified into four units on the basis of relative abundances of plagioclase pyroxene and high silica phase s unit distributions between 45 latitude exhibit moderate correlation with distinct provinces e g syrtis major aonium sinus defined by large scale morphology elevation and to some extent surface age suggesting that the spectral and compositional differences between these units are more strongly controlled by original bedrock mineralogy than by surface atmosphere interactions and alteration syrtis major exhibits a difference in mineralogy from the surrounding highlands suggesting a differing degree of fractional crystallization assimilation or source region composition areas with thick crust near the tharsis plateau exhibit lower abundances of olivine and greater plagioclase pyroxene ratios than surrounding highland terrains suggesting that magmas in this region may have undergone increased olivine fractionation regions where surface alteration is more likely to be the primary control on observed spectral signatures are the high latitude areas 45 where globally surfaces dominated by high silica phase s are most commonly found

late quaternary geology of the lower central plain thailand abstract the lower central plain or chao phraya plain located in the upper gulf of thailand has an average elevation of 2 m above the present mean sea level it is a fault bounded basin developed in the plio pleistocene epoch consequently the basin has been filled with quaternary sediment reaching a thickness of almost 2000 m of which only the upper 300 m is known the pleistocene deposits of the lower central plain represent a complex interplay of alluvial fluvial and deltaic environments of the chao phraya river and its tributaries the upper sequence of sand and stiff clay with iron oxide concretions on the surface was deposited in a fluviatile environment subjected to a regressive period in the late pleistocene the term chao phraya delta is used to define the landform where the chao phraya river interacted with marine processes as the sea level changed during the holocene transgression these strata indicated that the holocene sea reached its maximum height of 4 m above the present mean sea level around 6000 years b p from then on sea level fluctuated until it reached its present level around 1500 years b p this complex sea level history has caused the progradation of tidal flat and tide dominated delta deposits consisting of soft marine clay that covered the lower central plain to an average depth of 15 m in the bangkok area the soft marine clay or bangkok clay is the most important unit in the stratigraphic sequence in terms of land subsidence in the lower central plain evidence of coastal erosion is also considerable in the low tidal flat area on the west bank of the chao phraya river mouth and adjacent coast

chloride bearing materials in the southern highlands of mars chlorides commonly precipitate during the evaporation of surface water or groundwater and during volcanic outgassing spectrally distinct surface deposits consistent with chloride bearing materials have been identified and mapped using data from the 2001 mars odyssey thermal emission imaging system these deposits are found throughout regions of low albedo in the southern highlands of mars geomorphologic evidence from orbiting imagery reveals these deposits to be light toned relative to their surroundings and to be polygonally fractured the deposits are small

a global view of martian surface compositions from mgs tes thermal emission spectrometer tes data from the mars global surveyor mgs are used to determine compositions and distributions of martian low albedo regions two surface spectral signatures are identified from low albedo regions comparisons with spectra of terrestrial rock samples and deconvolution results indicate that the two compositions are a basaltic composition dominated by plagioclase feldspar and clinopyroxene and an andesitic composition dominated by plagioclase feldspar and volcanic glass the distribution of the two compositions is split roughly along the planetary dichotomy the basaltic composition is confined to older surfaces and the more silicic composition is concentrated in the younger northern plains

rocks of the columbia hills 1 the mars exploration rover spirit has identified five distinct rock types in the columbia hills of gusev crater clovis class rock is a poorly sorted clastic rock that has undergone substantial aqueous alteration we interpret it to be aqueously altered ejecta deposits formed by impacts into basaltic materials wishstone class rock is also a poorly sorted clastic rock that has a distinctive chemical composition that is high in ti and p and low in cr wishstone class rock may be pyroclastic or impact in origin peace class rock is a sedimentary material composed of ultramafic sand grains cemented by significant quantities of mg and ca sulfates peace class rock may have formed when water briefly saturated the ultramafic sands and evaporated to allow precipitation of the sulfates watchtower class rocks are similar chemically to wishstone class rocks and have undergone widely varying degrees of near isochemical aqueous alteration they may also be ejecta deposits formed by impacts into wishstone rich materials and altered by small amounts of water backstay class rocks are basalt trachybasalt lavas that were emplaced in the columbia hills after the other rock classes were either as impact ejecta or by localized volcanic activity the geologic record preserved in the rocks of the columbia hills reveals a period very early in martian history in which volcanic materials were widespread impact was a dominant process and water was commonly present

aminostratigraphy of quaternary coastal sequences in southern australia an overview abstract since the early 1980s amino acid racemisation reactions have been applied to the dating of quaternary coastal deposits in australia sequences of middle pleistocene age or younger have received the greatest attention amino acid racemisation has been applied as a relative and numeric dating method as well as for identifying remanie fossils and in delineating the spatial distribution of some fossil mollusc species the method has also been used to verify the radiocarbon ages of fossil molluscs from interstadial sediments it has also been used in studies of coastal neotectonics and in comparisons with other dating methods e g electron spin resonance and thermoluminescence the most reliable results are from replicate analyses of the hinge region of well preserved and diagenetically unmodified fossil bivalve molluscs from deeply buried situations i e 1 m molluscs have been dated from a range of sites around the southern australian coastline and include specimens of plio pleistocene age and from middle pleistocene oxygen isotope stage 7 ca 220 ka bp late pleistocene substage 5e ca 125 ka bp interstadial stage 3 45 to 30 ka bp last glacial stage 2 ca 18 ka bp and holocene sequences amino acid racemisation dating of the australian quaternary coastal record has 1 confirmed the widespread occurrence of last interglacial coastal strata and allowed their correlation with sequences of equivalent age from the northern hemisphere 2 identified strata of penultimate interglacial age and 3 confirmed the interstadial age of marine strata stage 3 in gulf st vincent south australia aminostratigraphic studies of the southern australian quaternary coastal record also indicate that sea levels during the penultimate interglacial stage 7 may have been higher than otherwise predicted on the basis of the oxygen isotope record

micropalaeontological evidence for deglacial marine flooding of the ancient courses of the river murray across the lacepede shelf southern australia abstract previous sub bottom profiling of the lacepede shelf southern australia had inferred the course of the palaeo river murray during periods of low sea level micropalaeontological analysis of two cores taken during the sst 02 07 cruise confirm these earlier observations and reveal the past existence of permanently open estuarine environments substantially larger than currently prevailing at the mouth of the terminal lakes of the river murray australia s largest exorheic river the characteristics of the sediment and contained microfossils provide substantial evidence for the repeated development of large oxygen depleting algal blooms sapropels detailed analyses of the ostracod and foraminifer microfaunas together with other fossil remains such as pteropods bryozoan sponge spicules and echinoid spines combined with the dating of selected ostracods and bivalve molluscs by ams radiocarbon and bivalve molluscs by amino acid racemization reveal rapid sediment accumulation within the ancient channels of the river murray under estuarine conditions the oldest infill relates to the end of the rapid sea level rise following meltwater pulse ia 13 600 cal years bp and the second one that coincides with the meltwater pulse ib at 11 500 11 000 cal years bp in both cases marine microfauna confirm the presence of marine incursions the palaeoenvironmental reconstructions based on microfossils presented here rely on the study of six southeastern australian contemporaneous estuaries where foraminifers and ostracods were collected together with some ecological data such as salinity dissolved oxygen and presence absence of aquatic vegetation

sublacustrine depositional fans in southwest melas chasma two depositional fan complexes have been identified on the floor of southwest melas chasma the western fan complex is located near the center of an enclosed basin in southwest melas chasma and is composed of multiple lobes with dendritic finger like terminations these fans are very flat and have a morphology unlike any other fan that has been previously identified on mars on the basis of the morphologic similarity of the western fan complex to the mississippi submarine fan complex we suggest that it may be a deep subaqueous fan depositional system there are numerous channels on the surface of the western fan complex and measurements of channel length width and sinuosity are consistent with channels observed on terrestrial submarine fans the eastern melas depositional fans are less well preserved and may be of deltaic or sublacustrine origin recognition of the fans supports earlier suggestions for the presence of a former lake in melas chasma and indicates that a significant body of water was present and stable at the surface of mars for at least 10 2 to 10 4 years

identification of carbonate rich outcrops on mars by the spirit rover decades of speculation about a warmer wetter mars climate in the planet s first billion years postulate a denser co2 rich atmosphere than at present such an atmosphere should have led to the formation of outcrops rich in carbonate minerals for which evidence has been sparse using the mars exploration rover spirit we have now identified outcrops rich in magnesium iron carbonate 16 to 34 weight percent in the columbia hills of gusev crater its composition approximates the average composition of the carbonate globules in martian meteorite alh 84001 the gusev carbonate probably precipitated from carbonate bearing solutions under hydrothermal conditions at near neutral ph in association with volcanic activity during the noachian era

marine transgressions in the west coast of saudi arabia red sea between mid pleistocene and present abstract marine abrasion terraces cut in coralline limestone formations are to be noticed at various elevations in the coastal plain of the west coast of saudi arabia in between jeddah and yanbu three prominent terraces occur at altitudes of 1 3 and 10 m above the present level coral limestone samples from the terraces were dated by the carbon 14 method the radiometric ages reveal four marine transgressions in the west coast of saudi arabia eastern red sea from the mid pleistocene to present sea level maxima were recorded at about 31 000 16 600 18 100 9980 yrs b p and mid holocene the absolute altitude of the sea levels during the transgressions could not be evaluated because of the tectonic instability of the region however it is evident that relative to the first marine transgression mid wurm interglacial upto 31 000 yrs b p the successive transgressions in the west coast of saudi arabia occurred at progressively lower levels

further evidence of the complexity of the racemization process in fossil shells with implications for amino acid racemization dating abstract simulated aging experiments with shells of ostrea anadara and katelysia spp from modern holocene and pleistocene marine sediments in southern south australia give further insight into the difficulties in using d l ratios of amino acids for quantitative age determinations evidence is given that the progress of racemization as monitored by changes in d l ratios with time is not only non linear but also may be reversed demonstrating a decrease in the observed degree of racemization the observed changes in d l ratio with time differ according to the age and the genus of shell and the amino acid examined katelysia spp gives less variable values than ostrea or anadara and similarly valine racemization and isoleucine epimerization are far less variable than aspartic acid racemization

martian layered fluvial deposits implications for noachian climate scenarios 1 fluvial deposits in a basin north of holden crater exhibiting a sinuous anabranching pattern are of deltaic or fan origin channel width and meander wavelength indicate persistent flow magnitudes of about 700 m3 s if these flows were produced by quasi periodic climate episodes involving typical terrestrial style precipitation the deposit required thousands to millions of years to accumulate however a scenario of deposition during a few short episodes of constant heavy precipitation resulting from large impacts cannot be excluded

fluvial sedimentary deposits on mars ancient deltas in a crater lake in the nili fossae region 1 new spacecraft observations in the nili fossae region of mars reveal two valley networks 80 and 200 km long that each formed distributary fans as they entered an ancient 40 km diameter impact crater an outlet channel on the eastern crater rim lying at an elevation above the fans suggests these fans formed as subaqueous deltas in a crater lake water flowing in the valley networks entered the crater and deposited the fans and ponded to a maximum depth of about 450 m the lake then overtopped and breached the crater rim incising it and dropping the lake level by 100 m geological evidence combined with the volume of water necessary to fill the crater suggests the duration of flow through this system was prolonged the existence of the deposits described here implies that the early martian environment supported overland flow and ponding of water for an extended period of time

mineralogy of the light toned outcrop at meridiani planum as seen by the miniature thermal emission spectrometer and implications for its formation 1 analysis of miniature thermal emission spectrometer mini tes data has led to the recovery of a pure end member spectral shape related to the light toned outcrop observed at meridiani planum data from the mer mossbauer spectrometer apxs and previous mini tes measurements were used to constrain a spectral library used to determine the mineralogy of the outcrop from this spectral shape linear deconvolution of the outcrop spectral shape suggests that it is composed primarily of al rich opaline silica mg ca and fe bearing sulfates plagioclase feldspar nontronite and hematite conversion of modeled mineralogy to chemistry shows good agreement with the chemical composition of the outcrops determined by apxs details of the analysis procedure and implications for the formation of the outcrop are discussed along with terrestrial analogs of the ancient environment at meridiani

alteration of immature sedimentary rocks on earth and mars recording aqueous and surface atmosphere processes the rock alteration and rind formation in analog environments like antarctica may provide clues to rock alteration and therefore paleoclimates on mars clastic sedimentary rocks derived from basaltic sources have been studied in situ by martian rovers and are likely abundant on the surface of mars moreover how such rock types undergo alteration when exposed to different environmental conditions is poorly understood compared with alteration of intact basaltic flows here we characterize alteration in the chemically immature carapace sandstone from antarctica a terrestrial analog for martian sedimentary rocks we employ a variety of measurements similar to those used on previous and current mars missions laboratory techniques included bulk chemistry powder x ray diffraction xrd hyperspectral imaging and x ray absorption spectroscopy through these methods we find that primary basaltic material in the carapace sandstone is pervasively altered to hydrated clay minerals and palagonite as a result of water rock interaction a thick orange rind is forming in current antarctic conditions superimposing this previous aqueous alteration signature the rind exhibits a higher reflectance at visible near infrared wavelengths than the rock interior with an enhanced ferric absorption edge likely due to an increase in fe3 of existing phases or the formation of minor iron oxy hydroxides more this alteration sequence in the carapace sandstone results from decreased water rock interaction over time and weathering in a cold dry environment mimicking a similar transition early in martian history this transition may be recorded in sedimentary rocks on mars through a similar superimposition mechanism capturing past climate changes at the hand sample scale these results also suggest that basalt derived sediments could have sourced significant volumes of hydrated minerals on early mars due to their greater permeability compared with intact igneous rocks less

a habitable fluvio lacustrine environment at yellowknife bay gale crater mars the curiosity rover discovered fine grained sedimentary rocks which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy this aqueous environment was characterized by neutral ph low salinity and variable redox states of both iron and sulfur species carbon hydrogen oxygen sulfur nitrogen and phosphorus were measured directly as key biogenic elements by inference phosphorus is assumed to have been available the environment probably had a minimum duration of hundreds to tens of thousands of years these results highlight the biological viability of fluvial lacustrine environments in the post noachian history of mars

coastal aminostratigraphy of the last interglaciation in southern australia abstract amino acid racemization data for marine molluscs of the last interglaciation from southern australia provide the basis for a predictive model for relative dating of late quaternary sequences genera analyzed include anadara sp katelysia sp glycymeris sp and fulvia sp that exhibit moderate racemization rates a genus effect on racemization is not evident in these taxa coefficients of variation for intershell d l ratio variation for each deposit are generally less than 12 the extent of racemization in molluscan fossils of the last interglaciation from temperate coastal settings in southern australia represents an exponential function of temperature and is in general accord with data from northern hemisphere sites with similar contemporary mean annual temperature values these data highlight the potential of amino acid racemization for global correlation programs the amino acid data from southern australia suggest however that a larger margin of variation may have to be accounted for in stratigraphic correlation as indicated by the greater scatter of data around the oxygen isotope substage 5e isochron these data have implications regarding the age resolving power of amino acid racemization

the magnitude and proximate cause of ice sheet growth since 35 000 yr b p the magnitude of late wisconsinan post 35 000 yr b p ice sheet growth in the northern hemisphere is not well known ice volume at 35 000 yr b p may have been as little as 20 or as much as 70 of the volume present at the last glacial maximum lgm a conservative evaluation of glacial geologic sea level and benthic 18o data indicates that ice volume at 35 000 yr b p was approximately 50 of that extant at the lgm 20 000 yr b p that is it doubled in about 15 000 yr on the basis of literature for the north atlantic and a sea surface temperature sst data compilation it appears that this rapid growth may have been forced by low to mid latitude sst warming in both the atlantic and pacific oceans with attendant increased moisture transport to high latitudes the sst ice sheet growth notion also explains the apparent synchroneity of late wisconsinan mountain glaciation in both hemispheres

the last interglacial shoreline in southern australia morphostratigraphic variations in a temperate carbonate setting abstract coastal marine strata of last interglacial age are preserved extensively around the southern australian coastline the sedimentary facies have many features in common with adjacent holocene coastal facies and contemporary peritidal environments but are partly lithified mostly elevated and laterally displaced inland sediments are dominantly biogenic skeletal carbonates of cool temperate water affinities foram mollusc coralline alga association surficial calcrete development has aided preservation of morphostratigraphic forms and sedimentary structures large coastal barrier complexes comprising aeolian dune foredune and back barrier lagoon facies characterize exposed coastal tracts facing the southern ocean in contrast broad low gradient peritidal complexes with a shoaling upward sequence of subtidal intertidal and supratidal mud sand flat facies characterize protected shorelines of major gulfs and embayments a similar upward shoaling sequence is preserved in back barrier lagoons along the more tectonically stable part of southern australia the last interglacial palaeo shoreline is consistently recorded at 2 m above present sea level this is an important regional datum that is significantly below the 6 m level globally attributed to this sea level highstand elsewhere neotectonic variations in shoreline elevation are clearly discernible with uplift of up to 18 m associated with quaternary volcanism near mount gambier the last interglacial strata contain a number of fossils with tropical affinities that no longer live in the local waters the presence of these fossils is consistent with warmer coastal waters during the last interglaciation but does not necessarily imply warmer oceanic waters or a warmer continental climate

mineralogical composition of sands in meridiani planum determined from mars exploration rover data and comparison to orbital measurements constraints on the mineralogical composition of low albedo low sulfur sands at meridiani planum are determined from mars exploration rover mer opportunity miniature thermal emission spectrometer mini tes mossbauer and alpha proton x ray spectrometer measurements results of this work show that the sand is olivine basaltic in composition with minor amounts of sulfate and a high silica phase glass or secondary amorphous silica measurements from all three instruments indicate that pyroxene is twice as abundant as olivine and that the pyroxene composition is dominated by the low calcium variety the volume abundance of olivine is constrained to be 10 15 results from detailed analyses of mer data are used to ground truth the spectral emissivity and mineral abundances derived from orbit with mars global surveyor tes data tes derived mineral abundances are within 5 of those derived from mer data which is generally within the statistical errors associated with tes derived phase abundances the agreement lends support to global and regional scale variations in mineralogical composition determined from tes data in previous studies an alternative method of least squares minimization is used for modeling the tes and mini tes data the benefits of this method are demonstrated by comparison with conventional least squares techniques previously used by tes data users

a late pleistocene transgression in thailand a marine molluscan fauna from ban praksa samut prakan province abstract a late pleistocene molluscan fauna sampled at ban praksa near the chao phraya river mouth lower central plain of bangkok thailand is herein analyzed and paleoecologically characterized revealing a shallow infralittoral coarse hard bottomed environment the comparison of the ban praksa association with several coeval ones recovered from phra pradaeng formation seems to be evidence of a 10 000 year hiatus between two separate groups of marine faunas possibly belonging to different interstadial transgressive peaks that occurred during the long term sea level regression following the last interglacial

amino acid racemization and radiocarbon dating of interstadial marine strata oxygen isotope stage 3 gulf st vincent south australia abstract concordant results for the extent of racemization of the amino acids aspartic acid leucine and valine and isoleucine epimerization in several mollusc genera support radiocarbon data that indicate an interstadial age oxygen isotope stage 3 45 000 to 30 000 yr b p for a sequence of mollusc rich carbonate muds in gulf st vincent south australia a numeric age of 46 500 9100 yr b p was obtained on marine molluscs from these sediments using a model based on apparent parabolic racemization kinetics in a global context the sequence represents one of the few well documented occurrences of marine strata of this age from a tectonically quiescent setting a sea level as high as 22 m is indicated for this interval amino acid racemization provides an important method for validating conventional finite radiocarbon ages close to the practical limits of radiocarbon dating and in studies of reworking

mineralogy of a mudstone at yellowknife bay gale crater mars sedimentary rocks at yellowknife bay gale crater on mars include mudstone sampled by the curiosity rover the samples john klein and cumberland contain detrital basaltic minerals calcium sulfates iron oxide or hydroxides iron sulfides amorphous material and trioctahedral smectites the john klein smectite has basal spacing of similar to 10 angstroms indicating little interlayer hydration the cumberland smectite has basal spacing at both similar to 13 2 and similar to 10 angstroms the larger spacing suggests a partially chloritized interlayer or interlayer magnesium or calcium facilitating h2o retention basaltic minerals in the mudstone are similar to those in nearby eolian deposits however the mudstone has far less fe forsterite possibly lost with formation of smectite plus magnetite late noachian early hesperian or younger age indicates that clay mineral formation on mars extended beyond noachian time

magnitude dependent variance of peak ground acceleration abstract we examine the variability of peak horizontal and vertical accelerations of the large california strong motion data set for the time period 1957 to 1991 and find a statistically significant dependence of the standard error on earthquake magnitude specifically the standard error decreases with increasing magnitude the analysis was conducted using a rigorous methodology that examines both earthquake to earthquake inter event variability and within earthquake intra event variability the magnitude dependence is stronger for inter event variability than intra event variability and stronger for horizontal peak acceleration than for vertical peak acceleration the data from the recent landers big bear and northridge earthquakes are consistent with these results

late quaternary marine isotope stages 6 1 seismic sequence stratigraphic evolution of the otago continental shelf new zealand abstract a proposed chronostratigraphic model for the late quaternary evolution of the otago continental shelf new zealand includes fluvially incised sequence boundaries eroded during marine isotope stages 2 4 and 6 bounding three sequences subdivided into lowstand transgressive and highstand regressive systems tracts datable material is limited to the uppermost 1 m of the sequence and consequently the model is based on correlation of new high resolution seismic reflection data geopulse to a compilation of independent global sea level curves a second chronostratigraphic model that lacks a stage 4 sequence boundary and distinct stage 3 highstand forced regressive deposit is discounted because its subsidence corrected paleoshoreline depths do not match lowstands in the eustatic curves or temporally constrained sequences at other far field locations in the preferred chronostratigraphic model sea level lowstands during stages 2 4 and 6 reached maximum depths of 126 131 m 101 111 m and 116 135 m respectively producing sequence boundaries landward pinching deltaic wedges on the outer otago shelf and submarine canyon incision lowstand paleoshoreline depths have been corrected for subsidence from thermal cooling sediment compaction and loading but may be erroneously deep owing to erosion of paleoshoreline indicators clastic shallow marine wedges and back barrier valley fill deposits accumulated during the stage 6 5 4 3 and 2 1 marine transgressions contrary to the traditional sequence stratigraphic model deltaic and strandline units deposited during highstand through falling sea level stages 5 4 3 2 1 volumetrically dominate otago late quaternary sequences discrete units and minor marine erosion surfaces within the transgressive and regressive systems tract deposits are interpreted as strong evidence for seventh 20 ka or higher order sea level fluctuations influencing sedimentation on the otago shelf

thermal emission spectroscopy of the silica polymorphs and considerations for remote sensing of mars 1 the possible existence of silica rich rocks on mars requires consideration of all of the candidate forms of silica that might exist there we synthesized coesite and cristobalite and obtained natural samples of tridymite opal a and opal ct the thermal emission spectra of these silica phases were analyzed and related to their crystal structure and crystallinity structural differences between the polymorphs result in unique spectral character and the degree and type of crystal ordering in opal ct results in cristobalite or tridymite like spectral features these spectra will be useful for analysis of thermal emission spectrometer tes data from mars while silica polymorphs are not modeled in deconvolution of the two main tes surface type spectra this does not preclude the possible detection of local abundances of these minerals on mars spectral detection of silica phases on mars would have implications for the volcanic and alteration history of the planet

relative sea levels and coastal sedimentation in southeast australia in the holocene abstract in recent years australian studies of relative sea level change have shown reasonable consistency on the termination date of the postglacial marine transgression at c 6 500 14c years bp the following stillstand period has been characterized in some regions by a slight falling trend from a high stand or in other areas by a level not easily distinguished from the present the latter situation occurs on the embayed coast of new south wales here studies of depositional environments and sequences within bed rock embayments have linked the holocene sea level history to patterns of sedimentation on the inner shelf in bay barriers and in estuaries deposition of quartz rich sand in shoreface flood tidal delta and backbarrier environments occurred during the marine transgre sion and the subsequent stillstand shell fragments from these deposits have been radiocarbon dated shoreline displacement continues to the present day partly in response to changes in availability of sand in the shoreface zone and partly in response to variations in regional storminess patterns a nd the great shroud of the sea rolled on as it rolled five thousand years ago herman melville moby dick

opaline silica in young deposits on mars high spatial and spectral resolution reflectance data acquired by the mars reconnaissance orbiter compact reconnaissance imaging spectrometer for mars crism instrument reveal the presence of h 2o and sioh bearing phases on the martian surface the spectra are most consistent with opaline silica and glass altered to various degrees confirming predictions based on geochernicall experiments and models that amorphous silica should be a common weathering product of the basaltic martian crust these materials are associated with hydrated fe sulfates including h 3o bearing jarosite and are found in finely stratified deposits exposed on the floor of and on the plains surrounding the valles marineris canyon system stratigraphic relationships place the formation age of these deposits in the late hesperian or possibly the amazonian implying that aqueous alteration continued to be an important and regionally extensive process on mars during that time

mars remote sensing analog studies in the badwater basin death valley california 1 the search for evaporites on mars has important implications for the role that liquid water has played in shaping the planet s geologic climatic and potential biologic history orbital investigations of surface mineralogy are crucial to this exploration effort with the exception of coarse grained gray hematite at a restricted number of sites and trace amounts of carbonate in globally distributed dust deposits the thermal emission spectrometer tes and thermal emission imaging system themis instruments have yet to find widespread mineralogical evidence of aqueously formed minerals this may reflect the coarse spatial resolution of tes 3 5 km pixel and low spectral resolution of themis 10 bands between 6 5 and 14 5 m spectral mapping in the badwater basin death valley california was conducted to better understand the capabilities of tes and themis in detecting evaporite minerals high resolution modis aster airborne simulator master data degraded to tes and themis spatial resolutions were used to evaluate the detection limits of sulfates and carbonates to assess the validity of this spectral remote sensing a quantitative ground truth analysis of surface mineralogy in the badwater basin was performed the analysis was based on thin section petrography x ray diffraction electron microprobe and laboratory and field thermal emission spectrometer analyses taken together the results of all five methods provided enough constraints for a robust interpretation that was in general agreement with the spectral remote sensing mapping study for 90 of the surface samples examined

stratigraphy and holocene evolution of the mud dominated chao phraya delta thailand abstract the central plain of thailand was formed over the last 8 7 kyr mainly by the deltaic processes of two major rivers the chao phraya and the mae klong the delta plain is the third largest delta plain in southeast asia after that of the mekong and the irrawaddy on the basis of sedimentological and paleontological analyses of samples from three boreholes and an open pit survey the evolution of the delta was clarified with high resolution 14 c dating after the maximum transgression at between 8 and 7 cal kyr bp the delta system migrated southward into the paleo gulf of ayutthaya a large mud shoal the sananivate mud shoal formed near the mouth of the paleo gulf between 7 and 3 cal kyr bp and facilitated its infilling as a result the delta has prograded rapidly particularly during the last 2 kyr deltaic sediment volume for the last 7 5 0 5 kyr shows that the average rate of sedimentation was 23 1 3 6 million t yr which is nearly the same as the present total sediment discharge from both rivers the comparatively wide delta plain relative to sediment discharge resulted from the stable sea level the shallow paleo gulf acting as a receiving basin and effective sediment trapping because of the mud shoal

quaternary marine terrace chronology north canterbury new zealand using amino acid racemization and infrared stimulated luminescence extensive marine terraces along the north canterbury coast of the south island of new zealand record uplift in this tectonically active area although the terraces have been studied previously applications of quaternary geochronological techniques to the region have been limited we use infrared stimulated luminescence irsl amino acid racemization aar and radiocarbon to determine ages of terraces at three locations glenafric motunau beach and haumuri bluff we develop an aar calibration curve for the mollusk species tawera spissa from sites of known age including the sedimentary sequence of the whanganui basin bayesian model averaging of the results is used to estimate ages of marine shells from the north canterbury terraces by using both irsl and aar we are able to confirm ages using two independent dating methods and to identify one irsl result that is likely in error we develop new age estimates for the marine terraces of north canterbury and propose correlations between sites this terrace chronology differs significantly from most previous studies highlighting the importance of numerical dating the most extensive terraces are from marine isotope stages miss 5a and 5c with partial reoccupation of one terrace during mis 3 whereas mis 5e terraces are notably lacking among those dated

the rocks of gusev crater as viewed by the mini tes instrument 1 the miniature thermal emission spectrometer mini tes on board the mars exploration rover spirit is part of a payload designed to investigate whether a lake once existed in gusev crater mini tes has observed hundreds of rocks along the rover s traverse into the columbia hills yielding information on their distribution bulk mineralogy and the potential role of water at the site although dust in various forms produces contributions to the spectra we have established techniques for dealing with it all of the rocks encountered on the plains traverse from the lander to the base of the columbia hills share common spectral features consistent with an olivine rich basaltic rock known as adirondack class beginning at the base of the west spur of the columbia hills and across its length the rocks are spectrally distinct from the plains but can be grouped into a common type called clovis class these rocks some of which appear as in place outcrop are dominated by a component whose spectral character is consistent with unaltered basaltic glass despite evidence from other rover instruments for significant alteration the northwest flank of husband hill is covered in float rocks known as wishstone class with spectral features that can be attributed uniquely to plagioclase feldspar a phase that represents more than half of the bulk mineralogy rare exceptions are three classes of basaltic exotics found scattered across husband hill that may represent impact ejecta and or float derived from local intrusions within the hills the rare outcrops observed on husband hill display distinctive spectral characteristics the outcrop called peace shows a feature attributable to molecular bound water and the outcrop that hosts the rock called watchtower displays a dominant basaltic glass component despite evidence from the rover s payload for significant alteration of some of the rocks no unambiguous detection of crystalline phyllosilicates or other secondary silicates has been observed by mini tes the mineralogical results supplied by mini tes provide no clear evidence that a lake once existed in gusev crater

quantitative compositional analysis using thermal emission spectroscopy application to igneous and metamorphic rocks the mineral composition of a suite of igneous and metamorphic rocks was determined using the thermal infrared emission spectra of these rocks in a linear spectral deconvolution algorithm this algorithm assumes that the infrared spectrum of each rock is a linear mixture of the component mineral spectra weighted by volume abundance a diverse suite of 36 common rock forming and accessory minerals was used in the deconvolution the model was tested by comparing the mineralogy derived from the infrared spectrum with petrographically estimated abundances for 45 igneous and 51 metamorphic rock samples the mineral abundances derived from these two techniques agree to within 67 15 for the primary minerals feldspar pyroxene quartz and calcite dolomite and 69 17 for secondary minerals such as micas and amphiboles these differences are comparable to the error for traditional thin section mode estimates which are 65 15 for major minerals and 5 for minor minerals the detection limit for the primary and secondary minerals found in the rocks analyzed ranged from 5 to 10 each major rock type studied here was easily distinguished by its spectral characteristics the best results in both the qualitative determination of the rock type and dominant minerals and the quantitative reproduction of absorption features and mineral composition were obtained for igneous rock samples for metamorphic rocks pelite and quartzo feldspathic samples gave slightly better results than calcareous or mafic samples a controlled analysis in which the end member suite was reduced based on an initial estimate of the rock type only improved the results by several percent for most primary and secondary minerals the quality of the obtained results demonstrates that a linear deconvolution of infrared emission spectra provides an accurate rapid technique for determining the quantitative mineral composition of rock samples in a laboratory and has application to future in situ measurements

quantitative compositional analysis of sedimentary materials using thermal emission spectroscopy 2 application to compacted fine grained mineral mixtures and assessment of applicability of partial least squares methods fine grained sedimentary deposits on planetary surfaces require quantitative assessment of mineral abundances in order to better understand the environments in which they formed one way that planetary surface mineralogy is commonly assessed is through thermal emission 6 50 m spectroscopy to that end we characterized the tir spectral properties of compacted very fine grained mineral mixtures of oligoclase augite calcite montmorillonite and gypsum non negative linear least squares minimization nnls is used to assess the linearity of spectral combination a partial least squares pls method is also applied to emission spectra of fine grained synthetic mixtures and natural mudstones to assess its applicability to fine grained rocks the nnls modeled abundances for all five minerals investigated are within 10 of the known abundances for 39 of the mixtures showing the relationships between known and modeled abundance follow non linear curves the poor performance of nnls is due to photon transmission through small grains over portions of the wavelength range and multiple reflections in the volume the pls method was able to accurately recover the known abundances to within 10 for 78 90 of synthetic mixtures and for 85 of the mudstone samples chosen for this study the excellent agreement between known and modeled abundances is likely due to high absorption coefficients over portions of the thermal infrared tir spectral range and thus combinations are linear over portions of the range pls can be used to recover abundances from very fine grained rocks from tir measurements and could potentially be applied to landed or orbital tir observations

mineralogy and chemistry of altered icelandic basalts application to clay mineral detection and understanding aqueous environments on mars we used a suite of techniques including those emulating compositional data sets obtained from mars orbit and obtainable at the mars surface to examine aqueous alteration of basaltic rocks from iceland as a mineralogic and geochemical analog for noachian environments on mars a sample suite was collected for laboratory measurement of 1 whole rock visible near infrared vnir reflectance and thermal infrared tir emission spectra 2 vnir and tir reflectance spectra of particle size separates derived from the bulk rock and from materials extracted from fractures vesicles 3 x ray diffraction xrd patterns for determination of quantitative modal mineralogy 4 major element chemistry using flux fusion of whole rock powders and 5 electron microprobe analyses of minerals in thin sections conclusions about aqueous alteration can be influenced by technique for these basalts whole rock chemical data showed scant evidence for chemical fractionation but tir vnir and xrd measurements identified distinctive assemblages of hydrous silicate minerals differing by sample xrd provided the most complete and accurate quantitative determination of sample mineralogy however vnir spectroscopy was the technique most useful for determining composition of low abundance smectite clays and tir spectroscopy was the most useful for recognizing hydrated silicates in thin surface coatings high spatial resolution mineralogical and chemical data sets were useful for understanding the texture and distribution of alteration products and variations in fluid chemistry no single approach provides a complete assessment of the environment of alteration demonstrating the importance of employing multiple synergistic mineralogical and geochemical techniques and instruments in exploration of rock strata from aqueous paleoenvironments on mars

diverse aqueous environments on ancient mars revealed in the southern highlands high resolution spectral images reveal many new exposures of hydrated minerals across the noachian southern highlands of mars several different phyllosilicates are observed with inferred accompanying phases ranging from zeolites to sulfates to chlorides each in distinct geologic settings hydrated sulfates are observed in several locations at mid latitudes and likely formed independently from the equatorial sulfates these assemblages suggest a greater diversity of aqueous environments on ancient mars than has previously been recognized and their distribution implies that alteration was widespread during the noachian period not restricted to a few locations

evidence for a noachian aged ephemeral lake in gusev crater mars gusev crater has long been considered the site of a lake early in martian history but the mars exploration rover spirit found no apparent evidence of lake deposits along its 7 km traverse from 2004 to 2010 although outcrops rich in mg fe carbonate dubbed comanche were discovered in the noachian aged columbia hills they were inferred to result from volcanic hydrothermal activity we now find evidence that the alteration of the comanche outcrops is consistent with evaporative precipitation of low temperature near surface solutions derived from limited water rock interaction with rocks equivalent to nearby outcrops called algonquin additional observations show that the algonquin outcrops are remnants of volcanic tephra that covered the columbia hills and adjacent plains well before emplacement of basalt flows onto the floor of gusev crater water limited leaching of formerly widespread algonquin like tephra deposits by ephemeral waters followed by transport and evaporative precipitation of the fluids into the comanche outcrops can explain their chemical mineralogical and textural characteristics

the composition and evolution of the continental crust rare earth element evidence from sedimentary rocks the composition of the present day upper crust inferred from the uniformity of sedimentary rock r e e rare earth element patterns is close to that of granodiorite a revised andesite model is used to obtain total crustal composition the lower crust is the composition remaining assuming that the upper crust one third of the total is derived from intracrustal partial melting the upper crustal r e e pattern has pronounced eu depletion eu eu 0 64 the lower crustal pattern has eu enrichment eu eu 1 17 and the total crust has no eu anomaly relative to chondritic abundances the eu depletion in the upper crust is attributed to retention of eu in plagioclase in the lower crust because plagioclase is not stable below 40 km 10 kbar the anomaly is intracrustal in origin the archaean upper crust has a different r e e pattern to that of the present day upper crust being lower in total r e e and la yb ratios and lacking an eu anomaly these data are used to infer the archaean upper crustal composition which resembles that of the present day total crust except that ni and cr contents are higher the archaean crustal composition can be modelled by a mixture of tholeiites and tonalite trondhjemites the latter have steep light r e e enriched heavy r e e depleted patterns consistent with equilibration with garnet and hence probable mantle derivation there is little reason to suppose that the archaean lower crust was different in composition from the upper crust except locally where partial melting episodes occurred the r e e evidence is consistent with isotopic and geological evidence for a low continental growth rate in the early archaean a massive increase to about 70 of the total crust between about 3000 and 2500 ma b p and a slow increase until the present day the change from archaean to post archaean r e e patterns in the upper crust is not isochronous but is reflected in the sedimentary rock r e e patterns at differing times in different continents on the basis of a model composition for the mantle 36 of the potassium 30 of uranium 15 of lanthanum and 3 of ytterbium are concentrated in the present continental crust this enrichment is related to ionic size and valency differences from common mantle cations e g mg fe pre 3 9 ga b p crusts were obliterated by meteorite bombardment no geochemical evidence exists for primordial anorthositic sialic or mafic crusts

successive foraminiferal faunas and inferred palaeoenvironments associated with the postglacial holocene marine transgression gulf st vincent south australia gulf st vincent is one of a pair of elongate triangular shallow water embayments into the southern coast of continental australia from the southern floor of this embayment within a shallow basi

paleoclimatic evidence for future ice sheet instability and rapid sea level rise sea level rise from melting of polar ice sheets is one of the largest potential threats of future climate change polar warming by the year 2100 may reach levels similar to those of 130 000 to 127 000 years ago that were associated with sea levels several meters above modern levels both the greenland ice sheet and portions of the antarctic ice sheet may be vulnerable the record of past ice sheet melting indicates that the rate of future melting and related sea level rise could be faster than widely thought

global distribution composition and abundance of olivine on the surface of mars from thermal infrared data 1 we used spectral indexing and linear deconvolution to compare thermal infrared emission spectra of fo91 fo68 fo53 fo39 fo18 and fo1 olivine samples to mars global surveyor thermal emission spectrometer tes data over low albedo regions of mars the fo91 fo68 fo53 and fo39 spectral end members were confidently identified on mars a range of compositions wider than inferred from martian meteorites small less than hundreds of square kilometers occurrences of the fo91 spectral end member are present in the rims of the argyre and hellas impact basins and may represent martian mantle materials the fo68 spectral end member is common throughout the highlands chasmata outflow channels and nili fossae region the fo53 spectral end member occurs in eastern syrtis major the nili fossae region and smooth floored craters of the highlands although less abundant than fo68 and fo53 the distribution of the fo39 spectral end member suggests that some olivine on mars is more fe rich than olivine in martian meteorites global maps of olivine show that 1 materials containing 10 20 of olivine are common in the southern highlands of mars 2 olivine is most common near the topographic dichotomy boundary and 3 olivine becomes uncommon near the poles suggesting that it may be influenced by topography and or latitude climate olivine is found in early noachian to amazonian terrains some of which may be coeval with phyllosilicate and sulfate deposits detected by omega implying that any early noachian wet period of mars climate history may have been globally inhomogeneous or insufficient to weather the olivine that remains today

variations in martian surface composition and cloud occurrence determined from thermal infrared spectroscopy analysis of viking and mariner 9 data viking infrared thermal mapper irtm and mariner 9 infrared interferometer spectrometer iris data were examined for evidence of spatial variations in the composition of surface materials and the abundance of atmospheric condensates the irtm instrument collected broadband spectral radiance in bands centered at 7 9 11 and 20 m these measurements were converted to emissivities at 9 11 and 20 m and used to construct multispectral images at five seasons ls 90 180 180 360 0 90 90 180 and 180 360 and at local times of 6 8 8 10 10 12 12 14 and 14 16 h 24 h equals one martian day during dusty periods ls 180 360 these images clearly revealed the presence of suspended dust during clear periods ls 0 180 the seasonal and diurnal variations in water ice cloud occurrence could be mapped using the 11 m irtm band clouds tended to occur over the tharsis region and the region between 0 and 60 w near the equator and to evolve from dispersed hazes to more localized hazes during the day as northern summer progressed during the viking period the northern clouds transitioned from a diffuse haze to a more concentrated zone of clouds in the equatorial region with a well defined northern boundary during clear periods the irtm multispectral data reveal significant absorptions at 9 11 and 20 m that are strongly correlated with surface albedo these absorptions are produced by surface materials and individual four point spectra show compositional variations within both dark and bright material types the iris instrument collected high spectral resolution 2 4 cm 1 data from 6 to 50 m unfortunately only 85 daytime spectra out of the 21 000 total collected were acquired after the intense global dust storm of 1971 subsided after ls 330 the close agreement of these spectra convolved to irtm resolution with the irtm surface spectra confirms that they also represent surface rather than atmospheric materials the irtm four point spectra show similarities with plagioclase feldspar minerals clays and pyroxenes although the low spectral resolution of irtm prevents definitive mineral identification carbonates do not compose a significant fraction of the dark region materials the iris surface spectra show similarities with feldspars clays and pyroxenes in the 8 12 m region but do not match any of these minerals well in the 18 25 m region overall the irtm and iris data are consistent with previous suggestions of mafic to ultramafic compositions but data provide stronger evidence that unweathered plagioclase feldspars may be significant components of the present surface together the irtm and iris reveal the presence of absorption features associated with surface materials which should permit detailed surface compositional mapping using future thermal ir spectral measurements

quantitative provenance analysis of sediments review and outlook provenance analysis of sediments is aimed at reconstructing the parent rock assemblages of sediments and the climaticphysiographic conditions under which sediments formed inferring sediment provenance from the final product a basin fill is anything but straightforward because the detrital spectrum evolves as the sediment is transported along the pathway from source to basin successful provenance analysis requires that the nature and extent of compositional and textural modifications to the detrital spectrum be recognised if not quantified the history of quantification in sediment provenance studies is summarised and illustrated by tracking two fundamental ideas the concept of the sediment petrological province or petrofacies and the relation between sandstone composition and plate tectonic environment progress in sedimentary provenance analysis has been closely linked with advancements in measurement technology a brief survey of modern data acquisition tools illustrates the possibilities and limitations of modern provenance research an operational definition of quantitative provenance analysis qpa is presented in which the central role of mass balance is acknowledged extension of this definition to include quantitative predictions obtained by forward modelling computer simulation of sediment production as well as methodological improvements in data acquisition and processing is needed to cover likely future developments in qpa the contributions to the special issue quantitative provenance analysis of sediments illustrate the intrinsic multidisciplinarity and rapid expansion of qpa d 2004 elsevier b v all rights reserved

three hundred eighty thousand year long stable isotope and faunal records from the red sea influence of global sea level change on hydrography stable isotope and faunal records from the central red sea show high amplitude oscillations for the past 380 000 years positive 18o anomalies indicate periods of significant salt buildup during periods of lowered sea level when water mass exchange with the arabian sea was reduced due to a reduced geometry of the bab el mandeb strait salinities as high as 53 and 55 are inferred from pteropod and benthic foraminifera 18o respectively for the last glacial maximum during this period all planktonic foraminifera vanished from this part of the red sea environmental conditions improved rapidly after 13 ka as salinities decreased due to rising sea level the foraminiferal fauna started to reappear and was fully reestablished between 9 ka and 8 ka spectral analysis of the planktonic 18o record documents highest variance in the orbital eccentricity obliquity and precession bands indicating a dominant influence of climatically driven sea level change on environmental conditions in the red sea variance in the precession band is enhanced compared to the global mean marine climate record specmap suggesting an additional influence of the indian monsoon system on red sea climates

empirical equations for the prediction of the significant bracketed and uniform duration of earthquake ground motion abstract the complete characterization of earthquake ground motion includes the length of the interval of strong shaking as well as the amplitude and frequency content of the time series there are relatively few published equations available for the prediction of strong motion duration from earthquakes which may in part be a consequence of the fact that the duration of shaking has generally not been considered in structural engineering recognizing that there are many applications for which an estimate of the duration of ground motion is needed this study presents new empirical predictive equations for a number of definitions of strong motion duration using the records from the next generation of attenuation nga global database of accelerograms from shallow crustal earthquakes the equations can be used to estimate ground motion durations from shallow crustal earthquakes of magnitude between m w 4 8 and 7 9 at distances up to 100 km from the source

global mineral distributions on mars 1 determining the mineralogy of mars is an essential part of revealing the conditions of the surface and subsurface a deconvolution method was used to remove atmospheric components and determine surface mineralogy from thermal emission spectrometer data at 1 pixel per degree ppd minerals are grouped into categories on the basis of compositional and spectral similarity and global concentration maps are produced all binned pixels are fit well with rms errors of 0 005 in emissivity higher rms errors are attributed to short wavelength particle size effects on dust covered surfaces significant concentrations 0 10 of plagioclase high ca pyroxene sheet silicates high si glass and hematite are detected and display distributions consistent with previous studies elevated concentrations of plagioclase and high ca pyroxene are consistent with basaltic surfaces and are located in low albedo highlands regions north of 45 s significant concentrations of plagioclase and sheet silicates high si glass and low concentrations of high ca pyroxenes are consistent with andesitic surfaces and are concentrated in both southern and northern high latitude low albedo regions andesitic surfaces in the southern hemisphere have a lower spectral contrast than northern surfaces an isolated surface located in solis planum is spectrally distinct but compositionally similar to other surfaces interpreted to be andesitic in composition concentrations of olivine below the detection limit correctly identify its presence in two of three locations potassium feldspar low ca pyroxene basaltic glass olivine sulfate carbonate quartz and amphibole are not detected with confidence at 1 ppd the results presented here indicate a predominance of volcanic compositions within martian dust free surfaces

quantitative compositional analysis of sedimentary materials using thermal emission spectroscopy 1 application to sedimentary rocks thermal emission spectroscopy is used to determine the mineralogy of sandstone and mudstone rocks as part of an investigation of linear spectral mixing between sedimentary constituent phases with widespread occurrences of sedimentary rocks on the surface of mars critical examination of the accuracy associated with quantitative models of mineral abundances derived from thermal emission spectra of sedimentary materials is necessary although thermal emission spectroscopy has been previously proven to be a viable technique to obtain quantitative mineralogy from igneous and metamorphic materials sedimentary rocks with natural variation of composition compaction and grain size have yet to be examined in this work we present an analysis of the thermal emission spectral 270 1650 cm 1 characteristics of a suite of 13 sandstones and 14 mudstones x ray diffraction and traditional point counting procedures were all evaluated in comparison with thermal emission spectroscopy results from this work are consistent with previous thermal emission spectroscopy studies and indicate that bulk rock mineral abundances can be estimated within 11 2 for detrital grains i e quartz and feldspars and 14 8 for all other mineral phases present in both sandstones and mudstones in comparison to common in situ techniques used for determining bulk rock composition clay sized to fine silt sized grained phase identification is less accurate with differences from the known ranging from 5 to 24 on average nevertheless linear least squares modeling of thermal emission spectra is an advantageous technique for determining abundances of detrital grains and sedimentary matrix and for providing a rapid classification of clastic rocks

a provisional aminostratigraphical framework for late quaternary marine deposits in buenos aires province argentina abstract amino acid analysis was carried out on 5 bivalve taxa mactra isabelleana corbula patagonica tagelus plebeius macoma uruguayensis and noetia bisulcata data from the two most common mactra isabelleana and corbula patagonica are reported in detail samples were collected from holocene shorelines ca 2000 6890 14 c yr b p along ca 350 km of the buenos aires province argentina the aminostratigraphy is in general agreement with the palaeoecological evidence and radiocarbon ages the deposits of the area of punta indio punta piedras in the north which show the highest d l ratios have a different geometry and a molluscan fauna of warmer water affinity than the remaining beach ridges and must be older they could correspond with the climatic optimum hypsithermal the deposits of samborombon and mar chiquita probably started accumulating immediately after deposition of the punta indio punta piedras deposits deposition at mar chiquita appears to have continued longer than at samborombon older d l ratios from pre holocene marine deposits are difficult to interpret without geochronological calibration

u series and amino acid racemization geochronology of bermuda implications for eustatic sea level fluctuation over the past 250 000 years abstract bermuda is a stable mid oceanic carbonate platform for which a particularly complete record of late pleistocene eustatic sea level fluctuation has been reconstructed from a detailed study of geological field relationships combined with an extensive programme of u series and amino acid racemization geochronology only twice in the past 250 000 yr has sea level in bermuda been above its present level once at approximately 200 k y when it stood at about 2 m and most recently at 125 4 k y when it stood at 5 1 m these times of interglacial high sea level are characterized by the development of patch reefs and marine calcarenites at elevations above present sea level episodes of lower sea stand onto the bermuda platform at elevations higher than 20 m are observed within the two interglacial periods and are characterized by the deposition of eolianites by contrast glacial periods are times of residual soil formation and deposition of speleothems in caves at elevations below present sea level excellent correlation is observed between the bermuda glacio eustatic sea level record and other marine and terrestrial paleoclimate records

clay mineral formation and transformation in rocks and soils three mechanisms for clay mineral formation inheritance neoformation and transformation operating in three geological environments weathering sedimentary and diagenetic hydrothermal yield nine possibilities for the origin of clay minerals in nature several of these possibilities are discussed in terms of the rock cycle the mineralogy of clays neoformed in the weathering environment is a function of solution chemistry with the most dilute solutions favouring formation of the least soluble clays after erosion and transportation these clays may be deposited on the ocean floor in a lateral sequence that depends on floccule size clays undergo little reaction in the ocean except for ion exchange and the neoformation of smectite therefore most clays found on the ocean floor are inherited from adjacent continents upon burial and heating however dioctahedral smectite reacts in the diagenetic environment to yield mixed layer illite smectite and finally illite with uplift and weathering the cycle begins again

emission spectroscopy of clay minerals and evidence for poorly crystalline aluminosilicates on mars from thermal emission spectrometer data 1 to understand the aqueous history of mars it is critical to constrain the alteration mineralogy of the martian surface previously published analyses of thermal infrared 6 25 m remote sensing data of mars suggest that dark regions have 15 20 clay minerals however near infrared 1 3 m spectral results generally do not identify widespread clay minerals thermal infrared detections of clays on mars are difficult to interpret owing in part to the relative paucity of published spectral analyses of clay minerals and clay bearing materials using similar spectra thermal infrared emission spectra in this study we present an analysis of the thermal emission spectral features 6 25 m or 400 1650 cm 1 of a suite of clay mineral reference materials and clay bearing rocks linking their spectral features to the crystal chemical properties of the clays on the basis of this context provided by the emission spectral analysis of clay minerals and clay bearing rocks we reconsider the evidence for clay minerals on mars from thermal emission spectrometer tes results we propose that global scale clay abundances determined from tes probably represent a geologically significant surface component though they may actually correspond to poorly crystalline aluminosilicates with similar si o ratios to clay minerals 0 3 0 4 rather than well crystalline clays if clay minerals or clay like materials on mars are poorly crystalline and or dessicated they may be detectable in the thermal infrared but not easily detected with near infrared data sets

interstadial coral reef terraces and relative sea level changes during marine oxygen isotope stages 3 4 kikai island central ryukyus japan abstract coral reef terraces are one of the best recorders of relative sea level changes during the last glacial cycle thus far knowledge of relative sea level record based on coral reefs during the marine oxygen isotope stage ois 3 has been limited to studies of the huon peninsula papua new guinea high precision a spectrometric 230 th 234 u dating demonstrated an offlapping sequence of five coral reef complexes ages of which are 66 64 62 55 and 52 ka in the northern part of kikai island central ryukyus of japan interstadial reefs characterized by deepening upward sequences of coral assemblages recorded three hemicycles from transgression to highstand at 52 62 and 66 ka during which these reefs were drowned these highstands in the relative sea level record can be correlated with the eustatic record reconstructed from the huon reef terraces and with the interstadials 14 18 and 19 of the gisp 2 oxygen isotope record this consistency confirms the huon sea level record of ois 3 and implies that the eustatic sea level responded to the millennial scale climate changes even during the glacial period of ois 4

elemental geochemistry of sedimentary rocks at yellowknife bay gale crater mars sedimentary rocks examined by the curiosity rover at yellowknife bay mars were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts no evidence of chemical weathering is preserved indicating arid possibly cold paleoclimates and rapid erosion and deposition the absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low temperature circumneutral ph rock dominated aqueous conditions analyses of diagenetic features including concretions raised ridges and fractures at high spatial resolution indicate that they are composed of iron and halogen rich components magnesium iron chlorine rich components and hydrated calcium sulfates respectively composition of a cross cutting dike like feature is consistent with sedimentary intrusion the geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of mars

detection of hydrated silicates in crustal outcrops in the northern plains of mars the composition of the ancient martian crust is a key ingredient in deciphering the environment and evolution of early mars we present an analysis of the composition of large craters in the martian northern plains based on data from spaceborne imaging spectrometers nine of the craters have excavated assemblages of phyllosilicates from ancient noachian crust buried beneath the plains cover the phyllosilicates are indistinguishable from those exposed in widespread locations in the southern highlands demonstrating that liquid water once altered both hemispheres of mars

analysis of terrestrial and martian volcanic compositions using thermal emission spectroscopy 1 determination of mineralogy chemistry and classification strategies we have examined and applied existing classification schemes for volcanic rocks and developed new schemes using thermal emission spectra of terrestrial volcanic rocks laboratory thermal infrared spectra 5 25 m at 2 cm 1 spectral sampling deconvolved modal mineralogies and derived mineral and bulk rock chemistries were used to distinguish basalt basaltic andesite andesite and dacite modal mineralogies derived from linear deconvolution of terrestrial volcanic rocks were compared to modes measured by an electron microprobe phase mapping technique to determine the accuracy of linear deconvolution in modeling specific mineral abundances one standard deviations of the absolute differences between modeled and measured mineral abundances range from 2 4 to 12 2 vol with an average standard deviation of 4 8 vol being in agreement with average uncertainties calculated in previous studies weighted average compositions of feldspars in the deconvolution generally overlap the measured ranges of plagioclase compositions and the presence of low calcium and high calcium pyroxenes was correctly identified bulk chemistries of volcanic rocks were derived with a relatively high degree of accuracy 1 standard deviations ranging from 0 4 to 2 6 vol by combining the compositions of spectrally modeled phases in proportion to their relative abundances in a particular sample these data were collectively used to examine existing and develop new volcanic rock classification schemes however no single classification scheme was effective in accurately classifying all samples multiple steps of classification were required to distinguish volcanic rocks reflecting the mineralogic diversity and continuum of compositions that exists in volcanic rock types in a companion paper hamilton et al this issue these schemes are applied to the classification of martian surface compositions

fossil mollusc faunas their bearing on the holocene evolution of the lower central plain of bangkok thailand abstract in this work fossil molluscan assemblages are analyzed in order to reconstruct the evolution of the northern gulf of thailand during the holocene the marine sediments bangkok clay formation of the lower central plain of bangkok and the coastal plain of phetchaburi were sampled at 16 localities obtaining fossil shells and mangrove peat whose 14c ages range from 9000 to 2000 cybp a statistical treatment of abundance data returned four major groups namely the dendostrea rosacea association intertidal mud the corbula fortisulcata mactra luzonica association shallow infralittoral sandy mud the nuculana mauritiana timoclea scabra association infralittoral sand spit and the timoclea scabra arcopagia pudica association infralittoral mud the data allowed both a stratigraphic correlation along two transects covering all of the holocene basin and the creation of digitalized maps showing the presumable extension of the thai paleogulf around the apex of flandrian transgression event about 5500 cybp

determining the modal mineralogy of mafic and ultramafic igneous rocks using thermal emission spectroscopy the modal mineralogies of 20 mafic and ultramafic igneous rocks were determined from their thermal infrared emission spectra using a linear deconvolution approach which uses a library of end member mineral spectra to model a bulk rock spectrum over 90 of the modes obtained from thermal emission spectra agree with modes obtained by traditional optical analyses to within the stated error of the optical analyses 5 15 vol library spectra of several compositions within a solid solution series e g plagioclase feldspars labradorite and bytownite were commonly used in each best fit model and are assumed to represent in combination a composition in the rock for which an identical mineral spectrum was unavailable in the library the accuracy of this assumption was evaluated by calculating a weighted average solid solution composition for plagioclase and or pyroxenes from the library minerals used in the model best fit of 14 rocks and comparing these compositions to the actual chemistries measured by electron microprobe or the optically estimated an the derived solid solution compositions are generally within 10 15 an or mg of the measured composition modal data derived from the spectra via the deconvolution were summed and converted to weight percent wt oxides for comparison to standard bulk chemistry data sio2 al2o3 and na2o k2o were generally slightly overestimated and feo and mgo were typically slightly underestimated modes and wt oxides were plotted on standard rock type classification diagrams and provide broadly accurate classifications demonstrating that the linear deconvolution technique is successful at deriving useful mineralogical information from thermal infrared emission spectra of bulk rock samples furthermore convolution of the laboratory data to spectral resolutions comparable to remote sensing instruments specifically the mars global surveyor thermal emission spectrometer demonstrates only a 5 vol increase in modal uncertainty for minerals present in abundances 10 vol this study thus provides a strong foundation for the application of this technique to mafic igneous sample spectra from both laboratory and remote sensing instruments

in situ evidence for an ancient aqueous environment at meridiani planum mars sedimentary rocks at eagle crater in meridiani planum are composed of fine grained siliciclastic materials derived from weathering of basaltic rocks sulfate minerals including magnesium sulfate and jarosite that constitute several tens of percent of the rock by weight and hematite cross stratification observed in rock outcrops indicates eolian and aqueous transport diagenetic features include hematite rich concretions and crystal mold vugs we interpret the rocks to be a mixture of chemical and siliciclastic sediments with a complex diagenetic history the environmental conditions that they record include episodic inundation by shallow surface water evaporation and desiccation the geologic record at meridiani planum suggests that conditions were suitable for biological activity for a period of time in martian history