bluuebunny/crossref_metadata_2025_split huggingface dataset:
Environmental analysis of basin and schwellen facies in the lower Zechstein of Germany
Authors: Paul J. 
Published: September 2007

Summary
The Zechstein basin had a schwellen and basin topography, inherited from the late Variscan regime. The basinal facies of the lower Zechstein, mostly thin euxinic shales and limestones, are uniform throughout the basin. Different facies occur at the basin rim and on the schwellen. The schwellen facies of the Kupferschiefer varies from black and red shales to very fossiliferous dolomites. Reefs and other biogenic sediments dominate the shallow-water basin rim environments of the first- and second-cycle carbonates (Ca1 and Ca2). A regression during deposition of the upper part of the first-cycle carbonate led to emergence of the schwellen. This event can be recorded throughout the Zechstein basin. The deposition of great amounts of anhydrite upon the schwellen increased the relief between palaeohigh and basin. Subsequent sedimentation of thick halite blanketed the topography and filled the basin.
Comments on the genesis and structure of the copper-polymetallic ore deposit of the Foresudetic Monocline, SW Poland
Authors: Tomaszewski J. B. 
Published: September 2007

Summary

The copper-polymetallic ore deposit is situated within the Foresudetic Monocline near its boundary with the Foresudetic Block. The copper-mineralized zone extends through a series of dolomites, dolomite/clay shales and white sandstones of the lowermost Zechstein and, possibly, the uppermost part of the Rotliegendes. Mineral compositions, the manner of their occurrence and the diverse internal structure of this stratified deposit all indicate a multistage origin. Synsedimentary mineralization took place in a reducing environment present both during deposition of the shales and dolomites and during sedimentation of the white sandstones. Black concretions containing large amounts of organic carbon, FeS
2
and FeO occur in the upper part of these sandstones. Mineralization also took place throughout diagenesis, mainly in the sandstones but also in the shales and, to a lesser degree, the dolomites.

Sedimentation was on an unstable shelf within the neritic zone. It is considered that natural marine aqueous solutions were enriched in metal ions (mainly Cu, Pb, Zn) by hot brines flowing out into the sedimentary basin through deep fissures, such as those in the Middle Odra fault zone, situated near the deposit.
The Leine Anhydrite of the Polish Zechstein: a significant lithostratigraphical marker-unit
Authors: Klapcinski J. 
Published: September 2007

Summary
Three lithostratigraphical members have been distinguished within the Leine Anhydrite of western Poland: (i) pseudospherulitic anhydrite, (ii) spherulitic anhydrite, and (iii) cryptospherulitic anhydrite. Because of its characteristic spherulitic texture and considerable lateral extent, the Leine anhydrite is considered to be a useful marker unit throughout a considerable part of the Central European Zechstein Basin.
The main types of carbonate rocks of the Kungurian evaporite basin of the Urals
Authors: Chuvashov B. I. 
Published: September 2007

Summary
The Kungurian basin of the Urals is a unique area for the study of evaporite sedimentation. All phases of evolution can be distinguished there, from a basin with a rich and diverse biota to a restricted one with high salt contents and scant biological communities. A similarity between English and German Zechstein sediments and the Kungurian strata of the Urals has long been noted. Some physical conditions of evaporite deposition may be inferred through a study of the associated carbonates.
Kungurian carbonates can be divided into three major groups: biogenic (organic), terrigenous and chemical. The organic carbonates are composed mostly of sediments trapped by blue-green algae and form small build-ups and algal mats, in both brackish-water (in the east) and high salinity (in the west) conditions. Coquinas are locally abundant. Clastic carbonates were transported as blocks, boulders, sands, muds, and in fine suspension. Great masses of micritic limestones accumulated by deposition from the latter. Numerous concretions, oolitic beds and packets of fine-grained dolomites without organic remains were laid down as chemical deposits and are related to the evaporites.
Basement and cover rock history in western Tethys: HT-LP metamorphism associated with extensional rifting of Gondwana
Authors: Hall Robert 
Published: September 2007

Abstract
High-temperature-low-pressure metamorphism of the deep crust is probable during continental lithospheric extension. The 75-65 Ma cooling ages of metamorphic and magmatic rocks preserved in overthrust crystalline slices in the southern Aegean are most plausibly explained by late Cretaceous extension of the Apulian continental margin, rather than by subduction-related magmatism. Metamorphism and magmatism at depth can be correlated with those stratigraphic features of the cover sequences that indicate extension. In particular, the puzzling ‘premier flysch’ of the region is interpreted as one consequence of peripheral uplift associated with stretching.
Holocene serial folding in the Zagros
Authors: Mann C. D. , Vita-Finzi C. 
Published: September 2007

Abstract
In the south-east Zagros Mountains of Iran, deformation during the Quaternary has occurred by serial folding, with the mountain front advancing westwards at 17 mm/yr. Coastal uplift during the Holocene indicates a horizontal slip of about 30 mm/yr. The geometry of the locked and nascent folds indicates compression by a horizontal force equivalent to between 0.134 and 0.790 kbar according to which model is adopted.
Gondwanaland and the evolution of the Indian Ocean
Authors: Tarling D. H. 
Published: September 2007

Abstract
In regions, such as the Indian Ocean, where geophysical data are largely lacking, reconstructions must be a compromise, allowing for the evolution of ‘passive’ margins and the inclusion of remanent continental blocks that are now isolated within the oceanic basins. Sea-floor spreading anomalies are re-examined in the context of the foregoing considerations, and emphasis is placed on the need to match anomalies that formed within the same transform segments. Despite subsequent attempts, it is considered that Norton and Sclater’s (1979) configuration of Gondwanaland and its Mesozoic-Tertiary breakup only need small, but significant modifications. These allow for the inclusion of small, but critically located continental units between the major continental blocks. Only age differences are proposed for most of their anomaly 16 reconstruction, now largely corresponding to anomaly 20 times. No changes are proposed to Norton and Sclater’s reconstruction for anomaly 34 times. Alterations to older reconstructions are mainly to allow for the inclusion of the Kerguelen, Gaussberg and Broken Ridges between India and Antarctica, and for the Agulhas-Falkland (Malvinas) Plateaux between Africa and Antarctica. The revised Gondwanaland reconstruction for early-middle Jurassic times appears to be more consistent with the geological and geophysical evidence, particularly reducing the need for differential motions of Sri Lanka and of the West Antarctic Peninsula. A review of the palaeomagnetic data indicates caution in the ability of extant data to distinguish between most reconstructions proposed during the last decade; considerable re-sampling and re-evaluation are required to adequately test between such Gondwanan models.
Lower Palaeozoic metamorphism in the Moine-Dalradian belt of the British Isles
Authors: Harte Ben 
Published: September 2007

Summary
Greenschist- to amphibolite-facies mineral assemblages occur which are of Proterozoic as well as lower Palaeozoic age in the Moine rocks but are only Lower Palaeozoic in the Dalradian rocks. The widespread age of high-grade metamorphism in the Dalradian is 520–490 Ma (Grampian), whilst in the Moines N of the Great Glen high-grade Lower Palaeozoic metamorphism is dated at 460–440 Ma. In Moine rocks, Grampian deformation and metamorphism may be absent N of the Great Glen but present S of the Great Glen, and this may indicate substantial movement on the Great Glen Fault between about 500 and 450 Ma. In addition to Moine metamorphism and deformation, the 460–440 Ma period appears to encompass diverse and extensive tectonic activity near the southern margin of the belt: thrusting in Connemara, Highland Border Downbend formation in Scotland and ophiolite emplacement in the Shetland Isles. A set of probably basement-controlled tectono-metamorphic domains in the Scottish Dalradian is suggested.
Evolution of the Iapetus Ocean and its borders in pre-Arenig times: a synthesis
Authors: Skehan James W. 
Published: September 2007

Summary

On the margins of the Laurentian continent the interval
c.
800-492 Ma was dominated by (1) rifting involving continental crust and (2) rift sedimentation with or without related volcanicity and plutonism, culminating in (3) the formation of the Iapetus Ocean and succeeded by (4) initial phases of compressional tectonics. The latter involved the approach of volcanic island-arc systems and the partial or complete obduction of ophiolites of the oceanic crust cutting through the slope-rise prism and, at least in some parts of the orogen, being thrust onto the continental-shelf deposits in the Cambrian and Tremadocian. These processes led to the closing of the ocean in the mid-Ordovician Taconian and the Silurian Caledonian orogenies. The earliest and most complete pre-Arenig orogenic movements are recorded in the Finnmarkian orogeny, including obduction of ophiolites in Scandinavia (520–480 Ma). Related sedimentation gaps, preceded by deformation and ophiolite obduction and/or uplift, were accompanied by tectonic melange development and/or volcanicity. These features are recorded widely from northern Britain and Ireland (Grampian orogeny), and from the Appalachians of Newfoundland (Burlington orogenic episode), Maine, USA, and Quebec, Canada (Penobscot orogeny). Movements interpreted as relating to the Penobscotian are now recognized as widespread in the US Appalachians. The Sardic orogenic phase in southern Europe (
c.
510 Ma) is associated with plutonism and metamorphism and may be related to late Cadomian III orogenic movements.

In the southeastern landmasses of Gondwanaland (Avalonian-Cadomian-Pan-African) essentially the same time interval (
c.
800–492 Ma) was also dominated initially by rifting of continental crust overlain by late Proterozoic shelf deposits and the obduction and folding of ophiolites (Cadomian I orogeny) and underlying rocks, followed by intrusion of late- to post-tectonic plutons (Bleida). Cadomian II resulted in the deposition of coarse clastics, volcanics and glacigenic sediments (Tiddiline), and folding, erosion and deposition of a thick wedge of late Proterozoic carbonate and clastic rocks with alkaline volcanics (Adoudounian) overlain conformably by lower and middle Cambrian that are overlain disconformably by Tremadocian clastic sediments. During the rifting phase continental fragments drifted away and/or became volcanic arcs with subduction zones and back-arc basins constituting the weakly orogenic Avalonian terrane to the W and the strongly orogenic but discontinuous belt forming a terrane characterized by Cadomian fragments between the Avalonian terrane of the British Isles and the W African craton. Stratigraphic columns and schematic time-slice stratigraphic profiles with interpreted tectonic environments from various parts of the orogen provide comparisons and contrasts in stratigraphic, faunal, structural, volcanic, plutonic and metamorphic evolution.
Polyphase tectonothermal evolution of the Scandinavian Caledonides
Authors: Dallmeyer R. D. 
Published: September 2007

Summary
A polyphase tectonothermal evolution characterizes many of the allochthonous sequences which constitute the Scandinavian Caledonides. Initial Late Cambrian consumption of Iapetus oceanic crust occurred outboard of the Baltoscandian margin with development of an island-arc above a west-dipping subduction complex. Imbrication, polydeformation and variably high-grade metamorphism of Baltoscandian miogeoclinal rocks and underlying Precambrian crystalline basement occurred within an accretionary prism which developed in the subduction complex. This resulted in eastward younging, diachronous metamorphism throughout the Early and Middle Ordovician. Cooling during subsequent uplift was regionally variable, and is reflected by the wide range of radiometric dates reported for the Baltoscandian allochthons (455–535 Ma). This early Caledonian activity has been termed the Finnmarkian orogeny; however, it is best viewed as a complex, diachronous series of tectonothermal events which variably affected the Baltoscandian margin from the Late Cambrian through the Middle Ordovician.
Almost complete closure of the Iapetus Ocean appears to have been accomplished by the Late Ordovician when eugeoclinal terranes which had developed along the Laurentian margin were tectonically juxtaposed with eroded remnants of the Late Cambrian-Middle Ordovician arc. Initial imbrication of the Laurentian eugeoclinal sequences with the arc occurred during the Early Silurian (Late Llandovery). These were subsequently imbricated and infolded with predeformed Baltoscandian allochthons. The resultant composite allochthon was subsequently thrust eastward onto Silurian sedimentary successions deposited over previously metamorphosed Caledonian basement. This sequence of Early Silurian to Early Devonian tectonic events has been collectively termed the Scandian orogeny; however, they are regionally diachronous and should be bracketed with the local controls available. Scandian dates of 425–430 Ma are locally recorded in allochthons along eastern portions of the orogen and they probably date initial nappe translation to higher crustal levels along the Baltoscandian margin. In lower structural units Scandian dates range from 410 Ma in central to 385 Ma in western portions of the orogen. These are interpreted to date rapid cooling during the uplift associated with a crustal rebound which followed eastward translation of overriding allochthons.
Granitoid plutonism in the Caledonian orogen of Europe
Authors: Stephens W. E. 
Published: September 2007

Summary
Granitoid plutonism is a feature of all major segments of the Caledonian orogen in NW Europe and Greenland. Available data on geological setting, age and composition are presented for each segment and are collated for use as the basis for a regional and temporal interpretation of magmatism during the Caledonian. Magmatism close to the northwestern foreland was dominantly alkaline whereas both alkaline and peraluminous compositions are represented on the southern foreland. Within the orogen early magmatism N of the Iapetus suture line was dominantly S-type resulting from crustal anatexis of dominantly metasedimentary rocks, while there is a later shift to predominantly I-type granitoid plutonism. S of the Iapetus suture line plutonism within the orogen in Scandinavia is essentially I-type, whereas in Britain and Ireland it has more S-type characteristics supporting recent propositions of two separate southerly plates. The overall pattern of plutonism contrasts markedly with that of younger subduction-related batholiths.
The current status of thermobarometry in metamorphic rocks
Authors: Essene E. J. 
Published: September 2007

SummaryInformation on pressure (P) and temperature (T) is a fundamental aspect of research on metamorphic terrains. Unfortunately, many workers employ thermobarometers that are not experimentally calibrated, are insensitive or too sensitive toP-Tchanges, depend on a priori assumptions of water pressure (such as most petrogenetic grids), or are rapidly reset on cooling. Many systems are based on inaccurate thermodynamic data, involve solids with inadequately characterized structural states, neglect effects of thermal expansion and compressibility, or require long extrapolations inP-T-Xspace. For instance, application of the widely used garnet-clinopyroxeneKDthermometer may require extrapolation to temperatures where current thermodynamic models of pyroxenes and garnets remain uncertain. Current versions of the Mg/Fe exchange thermometer for biotite-garnet involve substantial compositional extrapolations for many applications and the biotite is easily reset while cooling from higherT. The most widely employed barometer is based on dilution of the reaction grossular + kyanite + quartz = anorthite, but failure to correct molar volumes forP-T-Xmay yield systematic errors of 1–2 kbar for barometry of crustal metamorphites. Application of this barometer to rocks equilibrated atT< 600–650°C is presently unwarranted in view of unknowna-Xrelations of garnets and plagioclases at theseT. However, by careful selections, thermobarometry may be accurate to ±50°C and ±1 kbar in many metamorphic terrains if a variety of different equilibria can be applied. Well-calibrated barometers that are useful forTτ 600–650°C rely on continuous reactions based on equilibria such as almandine + rutile = ilmenite + sillimanite + quartz, garnet + quartz = ferrosilite + plagioclase, garnet + rutile = ilmenite + anorthite + quartz, and almandine + sillimanite = hercynite + quartz. An extensive survey of the recent literature on thermobarometry of individual metamorphic facies reveals the range ofP-Tencountered in each facies. Temperature estimates are in good agreement with the inferences of Turner (1968). Barometry reveals that the blueschist, amphibolite and granulite facies give way to the eclogite facies over the pressure range of 12–16 kbar.
Geothermobarometry of high-grade metapelites: simultaneously operating reactions
Authors: Aranovich L. Ya. , Podlesskii K. K. 
Published: September 2007

Summary

Experimental data on equilibria involving rock-forming minerals in high-grade metapelites (garnet, orthopyroxene, cordierite and plagioclase) have been used to derive an internally consistent system of mineralogical thermometers and barometers based on component reactions and excess mixing properties of solid solutions. Application of these data to a granulite-facies metapelite sample reveals that compositional inhomogeneity of minerals on a thin-section scale is likely to be a result of several reactions opening simultaneously at the retrograde stage of metamorphic evolution. The widely accepted practice of estimating pressure and temperature from separate reactions may thus lead to errors and misinterpretation of
P-T
paths.
A laser-microprobe study of argon isotopes in deformed pegmatites from the Northern Highlands of Scotland
Authors: Irwin James J. , Kirschbaum Charles , Lim Tek. H. , Powell Derek , Glassley William E. 
Published: September 2007

Summary

In the Highlands of Scotland, the Moine schists are cut by pegmatites that were deformed and metamorphosed after emplacement. The
40
Ar/
39
Ar
κ
ages of laser ‘pits’, in muscovite, feldspar, and some garnet and quartz crystals in two of these pegmatites are consistent with regionally well-established ages of metamorphism of the Moine. The ages of cores, rims and of different sizes of muscovite crystals are the same within errors. Individual crystals of garnet and quartz in the Ardnish pegmatite are heterogeneous in their argon isotopic composition, indicating that the last episode of metamorphism did not equilibrate the noble gas isotopes. Some quartz and garnet crystals from a pegmatite at Ardnish contain radiogenic
40
Ar generated in the last c. 420 Ma and a trapped component having a
40
Ar/
36
Ar ratio close to modern atmosphere. A few garnets from this same pegmatite also appear to contain t least one trapped component of
40
Ar with an
40
Ar/
36
Ar ratio > 10000.
The role of crustal anatexis and magma migration in the thermal evolution of regions of thickened continental crust
Authors: De Yoreo J. J. , Lux D. R. , Guidotti C. V. 
Published: September 2007

Summary

The results of numerical thermal models are presented that directly take into account crustal melting and the upward transfer of melts in the thermal evolution of regions of thickened continental crust. The results of these models indicate that in regions of moderate to high mantle heat flow (Q
m
> 30 mW m
−2
), extensive melting of the lower crust is likely, but will only moderately affect the rise in temperature of the lower crust. They also show that the ascent of those melts will drastically modify the pressure- temperature-time (
P-T-t
) paths followed by horizons in the upper plate, prolonging loading and producing widespread high-grade amphibolite-facies metamorphism. In these models, both the style and timing of metamorphism above zones of melting is controlled by those melts and, as a consequence of melting, as much as 30–50% of the orogenic root is eliminated by removal of the lower plate through the upward transport of melts and their erosion at the surface.
Pressure, temperature and structural evolution of the Sulitjelma fold-nappe, central Scandinavian Caledonides
Authors: Burton Kevin W. , Boyle Alan P. , Kirk Wendy L. , Mason Roger 
Published: September 2007

Summary

Pressure(
P
)-temperature(
T
) paths of regional metamorphism have been constructed for pelitic units of the Sulitjelma fold-nappe (SFN), part of the Köli Division of the Upper Allochthon of the Central Scandes. The SFN comprises the Skaiti Supergroup, a sequence of late Proterozoic supracrustal rocks, intruded by the lower members of the Sulitjelma Ophiolite, which is overlain by an Ordovician to Silurian sedimentary carapace, the Furulund and Sjönstå groups.

The
P-T
paths calculated from garnet zoning modelling are temporally related to texturally distinct periods of garnet growth, which can be correlated with regional deformation episodes. In the Furulund Group: (i) static overgrowth of a planar fabric in garnet cores corresponds to heating and compression to 470°C, 6 kbar; (ii) synkinematic growth corresponds to further heating but with decompression to 500°C, 5 kbar; (iii) static growth of inclusion-free rims occurred during near-isothermal compression to 6 kbar. In the Skaiti Supergroup pelites: (i) static growth of poikiloblastic garnet cores occurred during heating and compression to 500–520°C and 9–10 kbar; and (ii) static growth of inclusion-free rims corresponds to minor heating and significant decompression to 540°C and 7 kbar.

Comparison of mesoscale structural features with mineral growth indicates that (i) in both units is related to burial resulting from the closure of the marginal ocean basin floored by the Sulitjelma Ophiolite, while (ii) relates to the emplacement of the SFN onto Baltica, accompanied by overturning of the Ophiolite and its sedimentary cover. In the Furulund Group this occurred during eastward-directed simple shear deformation, giving rise to sheath folds and overturned isograds. In the Skaiti Supergroup there was little deformation during this period suggesting that most of the strain was being taken up by the Furulund Group. The final compressional phase (iii) seen only in the Furulund Group, relates either to the emplacement of the Skaiti Supergroup above the Furulund Group, or to out-of-sequence overthrusting of higher nappes.