bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new latest Telychian, Sheinwoodian and Early Homerian (Early Silurian) Standard Conodont Zonation
Authors: Jeppsson Lennart 
Published: November 2011

AbstractThe new standard conodont zonation includes, in succession from below: LowerPs. bicornisZone, UpperPs. bicornisZone, LowerP. procerusZone, UpperP. procerusZone, LowerK. ranuliformisZone, UpperK. ranuliformisZone,0. s. rhenanaZone, LowerK. walliseriZone, MiddleK. walliseriZone,K. patulaZone, uppermostK. walliserirange, postK. walliseriinterregnum,K. o. ortusZone and0. s. sagittaZone. Lower boundaries for each zone are defined or redefined. A less detailed biostratigraphic nomenclature at the superzone level is suggested for use where collections are inadequate: ThePterospathodusZonal group, the UpperPterospathodusZonal group, theP. amorphognathoidesZonal group, thePs. bicornisSuperzone, theP. procerusSuperzone, theK. ranuliformisSuperzone, theO. s. rhenanaSuperzone, theK. walliseriZonal group, the UpperK. walliseriSuperzone and theK. o. ortusSuperzone. These partly overlap and can be used according to the taxa present. The proposed zonation is applied to most known conodont sequences. The taxonomic concept of the taxa used is discussed; new taxa includeNudibelodina sensitiva, Ozarkodina paraconfluensandO. martinssoni.The species nameOzarkodina ortusis a senior synonym ofKockelella absidata.
The Scottish Carboniferous tetrapodCrassigyrinus scoticus(Lydekker)—cranial anatomy and relationships
Authors: Clack J. A. 
Published: November 2011

AbstractA new reconstruction of the skull ofCrassigyrinus scoticus(Lydekker) is provided, based on newly prepared material. A revised interpretation of the naris shows it in most respects to be like that of other Carboniferous tetrapods, lacking both an anterior tectal and a lateral rostral. However it does incorporate an enlarged septomaxilla, and part of the dorsal surface of the vomer is also visible within the naris of most specimens. Prominent paired buttresses run along the midline of the snout, and a single bowl-shaped interpremaxillary fenestra pierces the snout and palate but is not confluent with the naris or choana. A preopercular is probably absent. A new cladistic analysis placesCrassigyrinuswith the Viséan genusWhatcheeria, and puts those two taxa as a sister-clade to the anthracosaursProterogyrinusandPholiderpeton.Temnospondyls form a clade with loxommatids, and these two arms form a dichotomy crownward toGreererpeton, IchthyostegaandAcanthostegawhich are successive stemward plesions.
Strike-slip, terrane accretion and the pre-Carboniferous evolution of the Midland Valley of Scotland
Authors: Phillips E. R. , Smith R. A. , Carroll S. 
Published: November 2011

AbstractThe development of the Midland Valley of Scotland from Silurian times is re-examined. Earlier (Cambro-Ordovician) terrane accretion of the Midland Valley Terrane to the Laurentian continent by sinistral strike-slip continued to control basin development, sedimentary facies distribution and deformation from Llandovery through to at least early Devonian times. A widespread Mid- to Late-Wenlock strike-slip event has been recognised. This event is variable in its effect, but may indicate a direct link between the Midland Valley, Southern Uplands and Grampian terranes, suggesting that the terranes were juxtaposed by Mid-Wenlock times. In the Midland Valley this event was followed by a renewed phase of basin development with the deposition of ?Pridoli-Lower Devonian clastic sediments which was interrupted by the Lower Devonian volcanic event. There was a shift northwards in the focus of Lower Devonian basin development which was accompanied by a diachronous deformation event across the Midland Valley which resulted in inversion/uplift from early to middle Devonian times. This phase of deformation, uplift and erosion may be related to end-Caledonian transpression.
The mineral chemistry and petrology of Tertiary pitchstones from Scotland
Authors: Preston R. J. , Hole M. J. , Still J. , Patton H. 
Published: November 2011

AbstractSub-silicic to silicic pitchstones are widespread throughout the British Tertiary Igneous Province (BTIP), with examples being found at all the major igneous centres. Both highly porphyritic and almost completely aphyric varieties occur, and take the form of sills, dykes and lava flows. Here we present previously unreported mineral chemistry data on phenocryst and microcrystallite populations from a number of pitchstones from throughout the BTIP. Phenocryst assemblages are completely anhydrous, comprising mixtures of plagioclase, sanidine, fayalite, orthopyroxene, pigeonite, ferroaugite, ferrohedenbergite and quartz. Microcrystallite assemblages are also diverse, consisting of sanidine, ferrohedenbergite, fayalite and, occasionally, almost pure end-member ferrosilite, as well as hydrous phases such as ferrohornblende and biotite. Textural and mineral chemistry observations support interpretations derived from whole-rock and residual glass major element analyses, together with whole-rock trace element and the available Sr-Nd-Pb isotope data, that the Tertiary pitchstones of Scotland are either the products of intimate mixing between a range of basaltic magmas with hydrous crustal melts, or were formed by the crustal contamination of basaltic magmas.
A re-examination of the typology of peraluminous granite types in intracontinental orogenic belts
Authors: Villaseca Carlos , Barbero Luis , Herreros Victor 
Published: November 2011

AbstractConventional rock classification diagrams do not distinguish the variety of peraluminous rock series. Moreover, peraluminous granite types have not been clearly discriminated in recent revisions. The study of several peraluminous series in different intracontinental orogenic belts reveals that four distinct groups can be defined. Using an A-B diagram, these four groups are: (1) highly peraluminous granitoids (hP) characterised by high A values and typified by an increase in peraluminosity toward the most mafic varieties; (2) moderately peraluminous granitoids (mP) which occupy the intermediate field and generally show increasing peraluminosity towards the most felsic varieties; (3) low peraluminous granitoids (IP) which plot in the lowest part of the peraluminous field defining negative slope trends; (4) highly felsic peraluminous granites (fP) with poorly defined variation trends.In intracontinental orogenic belts, the genesis of peraluminous granitic series is favoured by the abundance of fertile crustal protoliths, mainly metapelites, metaigneous rocks and metagreywackes. The difficulty of attaining temperatures in excess of 950°C at lower crustal levels during the tectonothermal evolution of thickened crust, inhibits the partial melting of more basic sources. Although the physical parameters of the melting process influence their chemical and mineralogical characteristics, source rock composition ultimately determines the degree of peraluminosity of the granitic series.
Stress-forecasting: a viable alternative to earthquake prediction in a dynamic Earth
Authors: Crampin Stuart 
Published: November 2011

AbstractSelf-organised criticality of the crust appears to make deterministic earthquake prediction of time, place and magnitude of individual large earthquakes inherently impossible. This closes one line of approach to mitigating earthquake hazards. This paper suggests that a viable alternative to earthquake prediction is monitoring the build-up of stress before a large earthquake can occur. A new understanding of rock deformation allows stress changes to be monitored with seismic shear-wave splitting (seismic birefringence). With a suitable monitoring installation, this would allow the stochastic proximity of impending earthquakes to be recognised so that earthquakes could be forecast in the sense of recognising that crustal deformation was preparing for a large earthquake. Such stress-forecasting is not prediction, but, in many circumstances, a possible forecast crescendo of increasing urgency is exactly what is needed to best mitigate hazard to life and property.
The Miocene plutonic event of the Patagonian Batholith at 44° 30′ S: thermochronological and geobarometric evidence for melting of a rapidly exhumed lower crust
Authors: Parada M. A. , Lahsen A. , Palacios C. 
Published: November 2011

The Patagonian Batholith was formed by numerous plutonic events that took place between the Jurassic and the Miocene. North of 47° S, the youngest plutons occupy the axial zone adjacent to the Liquiñe-Ofqui Fault Zone, which is a major intra-arc strike-slip fault system active since the Miocene. The Queulat Complex, located at 44° 30′ S, includes two Miocene plutonic units: the Early Miocene Queulat diorite (QD) and the Late Miocene Puerto Cisnes granite (PCG). The QD includes hornblende + clinopyroxene diorites and tonalites, whereas the PCG includes slightly peraluminous garnet ± sillimanite granites and granodiorites.Eleven mineral Ar–Ar ages and three apatite fission track ages were obtained from the Queulat Complex and surrounding host rocks. Hornblende and biotite Ar–Ar ages ofc.16-18 Ma and 9-10 Ma, respectively, were obtained for the QD. The youngest ages of the QD are similar to the age of emplacement of the PCG as previously determined. Ar–Ar ages for muscovites and biotites of 6·6 ± 0·3 Ma and 5·6 ± 0·1 Ma, respectively, were obtained for the PCG. Biotites and muscovites from mylonites and pelitic hornfelses adjacent to the PCG yielded Ar—Ar ages between 5·1 Ma and 5·5 Ma. The apatite fission track ages of the QD and PCG overlap within the error margin (2•2 ± 1·1-3·3 ± 1·4 Ma).The Al-in-hornblende geobarometer yielded pressures for the QD emplacement equivalent to depths in the 19-24 km range, which is substantially higher than the 10 km depth estimated previously for the PCG emplacement. Exhumation rates (v) up to 2·0mm/yr were calculated for the time elapsed between the QD and PCG emplacements. Avvalue of 1·0mm/yr was calculated for the PCG subsequent to its emplacement. Using the silica—Ca-tschermak-anorthite geobarometer, we estimate the QD magma generation to be atc.33 km, which is similar to the current crustal thickness. Melting of mafic and metapelitic lower crust was possible at > 30km depth during a period whenvwas between 1·0mm/yr and 2·0mm/yr.
Granite-hosted mineral deposits of the New Ross area, South Mountain Batholith, Nova Scotia, Canada: P, T and X constraints of fluids using fluid inclusion thermometry and decrepitate analysis
Authors: Carruzzo Sarah , Kontak Daniel J. , Clarke D. Barrie 
Published: November 2011

The 370 Ma peraluminous South Mountain Batholith (SMB) intrudes Meguma Supergroup metasedimentary rocks in Nova Scotia. The New Ross area of the SMB contains polymetallic mineralisation (Sn, W, U, Mo, Cu and Mn) in pegmatite, greisen and vein directly or indirectly associated with highly evolved fractions of the SMB. Eight mineral deposits from this area have several fluid inclusion types hosted by quartz: (1) monophase liquid (L); (2) monophase vapour (V); (3) aqueous, L-V (4) aqueous, L-rich + solids; (5) aqueous, L-rich + halite. Inclusions have irregular to equant shapes and are pseudo-secondary or secondary. The irregularity and variability of L:V ratios within fluid inclusion populations suggest post-entrapment modifications of inclusions (i.e. necking).Thermometric data indicate three distinct fluids in terms of salinity: (1) 19-25 wt. % equiv. NaCl (rarely 14-25 wt. % NaCl equiv.), (2) 29-43 wt. % equiv. NaCl, and (3) 0-9 wt. % equiv. NaCl. Temperatures of first melting and ice/hydrohalife melting indicate CaCl2 in solution. Proximity of the deposits to Meguma Supergroup metasedimentary rocks suggests that this Ca component may be externally derived. The majority of the low-salinity fluid population has the composition of meteoric water. Electron microprobe analyses of artificially decrepitated mounds identify Na, Ca and K as major solutes, with a continuum in terms of compositions. Other solute components in the mounds are Fe and Ba, and a variety of metals of unknown speciation also occur (Cu, Zn, Fe, Ni). Homogenisation temperatures (Th) range from c. 80°C to 370°C, but for inclusion assemblages the range is 10°C to 20°C. Given the 3 kbar depth of emplacement of the SMB, estimated entrapment temperatures are c. 200°C to 550°C. The fluid inclusion data appear to reflect: (1) trapping of mixed Na-K-Ca brines during isobaric cooling in pegmatite and greisen deposits as indicated by large ranges in Th; (2) formation of deposits at different ambient pressures (i.e. depth); and (3) mixing of fluids of different reservoirs (i.e. magmatic, metamorphic, meteoric).
Stanwoodia, a new genus of probable early gymnosperms from the Dinantian of East Kirkton, Scotland
Authors: Galtier Jean , Scott Andrew C. 
Published: November 2011

ABSTRACTA new taxon of probable early gymnosperms is described from permineralised specimens showing excellent preservation of the tissues, from the late Lower Carboniferous (Dinantian), Brigantian, deposits of the Midland Valley of Scotland. Stanwoodia gen. nov., represented by the single species S. kirktonensis sp. nov., shows the combination of a primitive protostelic organisation with a dense secondary wood. It closely compares to the enigmatic genus Bilignea which was formerly referred with some reservations to the Cordaitales. Another interest of the new plant concerns the excellent preservation of the phloem with at least three different types of constituent cells including fibres. Stanwoodia also exhibits the oldest well-documented evidence of a sequent periderm or rhytidome in fossil plants.
Biometry, systematics and biogeography of the late Cambrian trilobiteMaladioidella abdita
Authors: Rushton Adrian W. A. , Hughes Nigel C. 
Published: November 2011

ABSTRACTThe restoration of deformed specimens of the trilobiteConocoryphe abditaSalter from the late Cambrian of Wales allows a re-evaluation of their systematics, synonymy with other species described from Siberia and Iran, and assignment to the idahoiid genusMaladioidella. Maladioidella abditais from theParabolina spinulosaBiozone, and most species similar to it occur in equivalent strata near the lower part of the Iverian Stage. Widespread homeomorphy in primitive libristomates is documented and presents difficulties for assessing relationships withinMaladioidellaand among related taxa. Both the genus as a whole and the speciesM. abditashow a widespread peri-Gondwanan distribution that crosses a range of latitudes and lithofacies and, to a limited extent, oceanic basins. No morphological features were discerned that might account for its unusual dispersal ability.
Petrogenesis of felsic I-type granites: an example from northern Queensland
Authors: Champion David C. , Chappell Bruce W. 
Published: November 2011

ABSTRACTFelsic I-type granites and associated volcanic rocks of Carboniferous age are extensively developed over an area of 15,000 km2 in northern Queensland. These granites have been subdivided into four supersuites: Almaden, Claret Creek, Ootann and O'Briens Creek.Granites of the Almaden Supersuite are intermediate to felsic (56-72% SiO2) and are characterised by high K2O, K/K(K + Na), Rb, Rb/Sr, Th, U and relatively low Ba and Sr. The Claret Creek Supersuite granites are a little more felsic (65-77% SiO2), and are chemically distinctive, having higher A12O3, CaO, Na2O and Sr, and lower K2O, Rb, Th and U than granites of the Almaden Supersuite.Granites of the Ootann and O'Briens Creek supersuites all contain more than 70% SiO2 and these comprise more than 90% of the total area of granites. These two supersuites are characterised by low Sr, Sr/Y and large negative Eu/Eu*, with the more evolved rocks becoming strongly depleted in TiO2, FeO* MgO, CaO, Ba, Sr, Sc, V, Cr, Ni, Eu, CeN/YN and K/Rb, and enriched in Rb, Pb, Th, U and Rb/Sr. Granites belonging to the O'Briens Creek Supersuite contain significantly higher abundances of HFSE, HREE and F (0·2-0·5 wt%) than those of the Ootann Supersuite, and as such have developed some characteristics of A-type granites.Geochemical and isotopic properties suggest that all granites are of crustal derivation. The granites of all supersuites have very similar initial 87Sr/86Sr and εNd of 0·710 and −7·0–−8·0, respectively, except where they outcrop within Proterozoic country rocks, when they have more evolved εNd (−8·0–−11·0). Depleted-mantle model ages cluster around 1·5 Ga. The isotope systematics and geochemistry indicate that these granites were not derived from the equivalents of any exposed country rocks.Models for the petrogenesis of these granites all appear to require the involvement of a long-lived and isotopically homogeneous crustal protolith, that most probably underplated the crust in the Proterozoic. Granites of the two more felsic supersuites were either derived by varying degrees of partial melting from this protolith of andesitic to dacitic composition, and/or were produced by a two-stage process by remelting of intermediate rocks similar in composition to the mafic end-members of the Almaden Supersuite. The resulting primary partial melts for the Ootann and O'Briens Creek supersuites underwent extensive, high-level, feldspar-dominated, crystal fractionation.
Proterozoic granite types in Australia: implications for lower crust composition, structure and evolution
Authors: Wyborn L. A. I. , Wyborn D. , Warren R. G. , Drummond B. J. 
Published: November 2011

ABSTRACTGranites and their associated comagmatic felsic volcanic rocks occur in most Proterozoic provinces of Australia. Using multi-element, primordial-mantle-normalised abundance diagrams and various petrological characteristics, Australian Proterozoic granites can be subdivided into five groups: (i) I-type, Sr-depleted, Y-undepleted, restite-dominated, (ii) I- type, Sr-depleted, Y-undepleted, fractionated, low in incompatible elements, (iii) I-type Sr-depleted, Y-undepleted, enriched in incompatible elements (anorogenic granites), (iv) I-type, Sr-undepleted, Y-depleted, (v) S-type, Sr-depleted, Y-undepleted. The four Sr-depleted groups dominate, and group (iv) is of very limited extent. A comparison of these Proterozoic granites with Australian and Papua New Guinean granites of other time periods shows that these characteristic Sr-depleted Y-undepleted patterns are also dominant in early Palaeozoic granites. They are significantly different from those of granites in modern island arcs associated with subduction, and with most granites from Archaean terranes, where the multi-element diagrams are dominated by Sr-undepleted, Y-depleted patterns.The Sr-depleted, Y-undepleted patterns are thought to indicate source regions that contained plagioclase but not garnet, whilst the Sr-undepleted, Y-depleted patterns are taken to correspond with the presence of garnet, but not plagioclase, in the source rocks. The Sr-depleted, Y-undepleted patterns also only occur in regions where the lower crustal structure is dominated by an underplated mafic layer with a P-wave velocity of 7·2-7·-4 km/s. In contrast, in regions where the granites are dominated by Sr-undepleted, Y-depleted patterns, such as in the Archaean and in Cainozoic island arcs, this intermediate velocity layer is not present, and the crust-mantle boundary is very sharp.Two other distinctive compositional changes have been noted among the I-type granites of different age. Firstly, Na is highest in Archaean and Cainozoic granites, and lowest in early Proterozoic granites; Palaeozoic and Mesozoic granites have intermediate values. Secondly, late Archaean and Proterozoic granites are the most enriched in K, Th and U, while the Cainozoic and early Archaean tonalites are the most depleted; Palaeozoic and Mesozoic granites again contain intermediate amounts of those elements.
Anorogenic granite magma genesis: new isotopic data for the southern sector of the British Tertiary Igneous Province
Authors: Meighan I. G. , Fallick A. E. , McCormick A. G. 
Published: November 2011

ABSTRACTIt is now generally accepted that British Tertiary granites contain crustal and mantle components. Genesis principally by differentiation of crustally contaminated basaltic magmas is widely held and silicic melts with some remarkable trace element similarities were generated within different upper crust along the St Kilda/Skye - Carlingford zone.New whole-rock (and mineral) O isotope data for the southern sector of the province (N Arran, Ailsa Craig, Mourne Mountains, Slieve Gullion, etc) reveal that δ18O lies in the range +5·1 to +9·7‰ for most of the analysed granites, meteoric water-rock interaction having been in general less intensive than at Skye and Mull. Nevertheless, highly 18O-depleted country rocks (with δ18O<0) exist adjacent to the N Arran and Mourne Mountains granite plutons. There is as yet no evidence for the existence of low -18O granitic melts in this southern sector where magmatic δ18O compositions (up to c. + 9·5‰) can be inferred for some of the intrusions.New Nd (and Sr) isotope data indicate that although there is some similarity in initial 87Sr/86Sr ratios between the northern and southern sector granites, in northeastern Ireland initial εNd values for the analysed Tertiary acid major intrusions range from −3·9 to −4·5. This is in marked contrast to the Skye granites, some of which have values below −20, reflecting the involvement of different lithosphere.
Granite sheeted complexes: evidence for the dyking ascent mechanism
Authors: Hutton Donald H. W. 
Published: November 2011

ABSTRACTA review of granite emplacement mechanisms in transcurrent, extensional and contractional (thrust sense) shear zones reveals that in all three tectonic settings the plutons have been constructed by multiple granite sheeting parallel to the shear zone walls and deformation fabrics. The sheets and plutons are non-Andersonian in type and were emplaced obliquely to the principal stress directions. Their shape and orientation is more likely to reflect the exploitation of faults and shear zones which were active during emplacement. Sheeting (dyking) is therefore also likely to be the mechanism of ascent along fault zones in the crust.
Peraluminous granites: the effect of alumina on melt composition and coexisting minerals
Authors: Holtz François , Johannes Wilhelm , Pichavant Michel 
Published: November 2011

ABSTRACTLiquidus phase relationships at H2O-saturated and -undersaturated conditions and 2 kbar in the systems Qz-Or-Ab (SiO2-KAlSi3O8-NaAlSi3O8), Qz-Or-Ab-Al2O3, and subsystems are compared and discussed. In the peraluminous systems (i.e. when melts are saturated with respect to mullite) the liquidus temperatures are lowered by 40-55°C for compositions in the quartz primary field and by 15-25°C for cotectic compositions. The composition of the Qz-Ab eutectic and of the minimum are slightly shifted towards more Qz-rich compositions (minimum composition at P(H2O) = 2 kbar in the system Qz-Or-Ab-A12O3, saturated with respect to mullite: Qz40Or23Ab37). In melts saturated with sillimanite or mullite, the effect of high Al content may be lower for the Qz-Or than for the Qz-Ab eutectic.The depression of the liquidus temperatures may be partly related to the higher H2O solubility in melts saturated with respect to mullite. The solubility of H2O in a melt with a composition of Qz28Or34Ab38 at 2 kbar and 800°C is 5·77 ± 0·15 wt% H2O and 6·36 ± 0·30 wt% H2O in a melt with the same Qz/Or/Ab proportions but saturated with respect to mullite.The effect of high Al contents on the Mg and Fe contents of Ca-free granite melts was investigated at 775°C-3 kbar (melts coexisting with phlogopite), and at 820°C-2 kbar (melts coexisting with biotite and spinel), under NNO buffer conditions. Less than 0·15 wt% MgO is incorporated in subaluminous melts coexisting with phlogopite, whereas peraluminous melts (2·9 wt% normative corundum) contain 0·6–0·7 wt% MgO. A similar behaviour of the MgO content is observed for melts coexisting with biotite. In contrast, no significant effect of high Al contents on the FeO content of melt coexisting with biotite was observed. This suggests that the Fe/Mg ratio may be significantly lower in peraluminous than in subaluminous granitic melts.