bluuebunny/crossref_metadata_2025_split huggingface dataset:
Emitting-state properties of square-planar dithiocarbamate complexes of palladium(II) and platinum(II) probed by pressure-dependent luminescence spectroscopy
Authors: Genre Caroline , Levasseur-Thériault Geneviève , Reber Christian 
Published: October 2009

Temperature- and pressure-dependent Raman and luminescence spectra of four crystalline complexes of palladium(II) and platinum(II) with chelating diethyldithiocarbamate (EDTC) and pyrrolidine-N-dithiocarbamate (PDTC) ligands are reported. The crystal structure of [Pd(PDTC)2] was resolved at 120 K. Luminescence band maxima are observed at approximately 14 500 cm–1and 16 000 cm–1for the palladium(II) and platinum(II) complexes, respectively. Pressure leads to blue shifts of the band maxima by +9 and +13 cm–1/kbar for [Pd(EDTC)2] and [Pd(PDTC)2], and +15 cm–1/kbar for [Pt(EDTC)2]. These spin-forbidden d–d luminescence transitions have lifetimes of approximately 600 µs at temperatures below 20 K. Luminescence intensities at room temperature are low, but they increase significantly with external pressure. The experimental results show that strong increases of luminescence intensities caused by pressure are not limited to complexes with monodentate ligands, a result providing insight on the coordinates with emitting-state distortions responsible for this effect.
Latest Danian carbon isotope anomaly and associated environmental change in the southern Tethys (Nile Basin, Egypt)
Authors: Bornemann André , Schulte Peter , Sprong Jorinde , Steurbaut Etienne , Youssef Mohamed , Speijer Robert P. 
Published: October 2009

Abstract:

During the Palaeocene and Eocene Epochs (65.5–33.9 Ma) the Earth experienced the warmest conditions of the Cenozoic. This Palaeogene greenhouse episode is characterized by several short-lived negative carbon isotope (δ
13
C) excursions, which are usually interpreted as transient warming events (‘hyperthermals') as indicated by rising temperatures of surface and bottom waters, and accompanied carbonate dissolution in deep-sea settings. Among these events, the Palaeocene–Eocene Thermal Maximum (PETM,
c
. 55.5 Ma) is globally the best documented and most prominent. Further negative δ
13
C anomalies have recently been identified in the Eocene, but the early to middle Palaeocene has mostly been neglected. Here, benthic foraminiferal δ
13
C records are presented from four upper Danian–lower Selandian sections in the Nile Basin (eastern Egypt). All records show a negative δ
13
C shift with an amplitude of up to 2‰ at the base of planktonic foraminiferal subzone P3b (
c
. 61 Ma). The supra-regional nature of this event is emphasized by correlation with a well-dated, similar δ
13
C record from Zumaia (Spain). Lithological changes, the δ
13
C signature and biotic responses strongly resemble those of the PETM in Egypt, which leads to the hypothesis that this ‘Latest Danian Event' (LDE) may represent another early Palaeocene hyperthermal.
Petrology, Sr–Nd–Hf isotopic geochemistry and zircon chronology of the Late Palaeozoic volcanic rocks in the southwestern Tianshan Mountains, Xinjiang, NW China
Authors: ZHU YONGFENG , GUO XUAN , SONG BIAO , ZHANG LIFEI , GU LIBING 
Published: October 2009

Abstract:

The Late Palaeozoic volcanic rocks, mainly consisting of basalt, trachyte, trachy-andesite, andesite and rhyolite, widely distributed in the southwestern Tianshan Mountains, have been proven to be formed during Late Devonian to Late Carboniferous time (>361–313 Ma) based on zircon sensitive high-resolution ion microprobe dating. The geochemistry demonstrates that the studied volcanic rocks represent a continental arc formed during the subduction of the Palaeo-southern Tianshan Ocean. The ε
Hf(T)
values of zircons in these volcanic rocks vary from +1.4 to +15.6 with weighted average values of +9.5 (Late Devonian), +8.9 (Early Carboniferous) and +10.3 (Late Carboniferous), suggesting a depleted mantle origin. However, the Late Devonian basaltic samples have negative ε
Nd(T)
values (from −5.16 to −3.07) and high initial
87
Sr/
86
Sr ratios (0.7073–0.7098), whereas the Early Carboniferous volcanic rocks mostly have positive ε
Nd(T)
values (from −0.18 to +3.07) with low initial
87
Sr/
86
Sr ratios (0.7044–0.7067), and the Late Carboniferous volcanic rocks are characterized by high ε
Nd(T)
values (+2.79 to +5.89) and low initial
87
Sr/
86
Sr ratios (0.7032–0.7054). The assimilation–fractional crystallization (AFC) model is used to explain the isotope characteristics of the Late Devonian volcanic rocks in the southwestern Tianshan Mountains. Calculation shows that the Late Devonian samples could be formed by the AFC process between depleted mantle and continental crust. The Carboniferous basaltic rocks originated by partial melting of the mantle wedge.

Supplementary material:

Data are available at
http://www.geolsoc.org.uk/SUP18378
.
Eclogite–high-pressure granulite metamorphism records early collision in West Gondwana: new data from the Southern Brasília Belt, Brazil
Authors: RENO BARRY L. , BROWN MICHAEL , KOBAYASHI KATSURA , NAKAMURA EIZO , PICCOLI PHILIP M. , TROUW RUDOLPH A.J. 
Published: October 2009

Abstract:

Nappes in the southern sector of the Southern Brasília Belt record suturing of the Paranapanema Block and Socorro–Guaxupé Arc with a subducted passive margin on the western side of the São Francisco Craton. We report secondary ion mass spectrometry U–Pb zircon ages that for the first time constrain the age of: (1) retrograded eclogite from a block along the tectonic contact beneath the uppermost nappe in a stack of passive margin-derived nappes; (2) high-pressure granulite-facies metamorphism in the uppermost passive margin-derived nappe; (3) high-pressure granulite-facies metamorphism in the overlying arc-derived nappe. Rare zircons from a retrograded eclogite yield a
206
Pb/
238
U age of 678 ± 29 Ma, which we interpret as most likely to date close-to-peak-
P
metamorphism and to provide a minimum age for detachment of the overlying passive margin-derived nappe from the subducting plate. Zircon associated with ilmenite in samples from two structural levels in the passive margin-derived high-pressure granulite nappe yields
206
Pb/
238
U ages of 648 ± 12 and 647 ± 11 Ma, and Ti-in-zircon crystallization temperatures from
c
. 860 °C down to
c
. 785 °C, but skewed toward the lower part of the range. These data indicate zircon formation during cooling from around peak
T
to the solidus, consistent with the high-
T
retrograde
P
–
T
path deduced from microstructures linked to phase assemblage fields in isochemical phase diagrams. Rb–Sr multi-mineral–whole-rock isochrons from two samples from close to the bottom of this nappe date formation of a retrograde sillimanite-bearing penetrative fabric to
c
. 590 Ma at temperatures of
c
. 750 °C (based on Ti-in-quartz thermometry). Rare zircons from leucosome in high-pressure granulite from the overlying arc-derived nappe yield a
206
Pb/
238
U age of 622 ± 28 Ma and Ti-in-zircon crystallization temperatures from
c
. 970 °C down to
c
. 820 °C, which we interpret to record formation of zircon during cooling from peak high-pressure granulite-facies conditions. These ages indicate that the first stage of craton amalgamation in West Gondwana may have occurred earlier than previously inferred.

Supplementary material:

Geochemical and geochronological data are available at
http://www.geolsoc.org.uk/SUP18377
.
Mechanical stratigraphy and folding style of the Lurestan region in the Zagros Fold–Thrust Belt, Iran
Authors: Farzipour-Saein A. , Yassaghi A. , Sherkati S. , Koyi H. 
Published: October 2009

Abstract:
The structural style of the folds from the central part of the Lurestan salient located in the NW portion of the Zagros Fold–Thrust Belt has been studied by constructing a regional balanced cross-section from field data, existing geological maps, seismic profiles, stratigraphic surface sections and well data. The regional balanced structural cross-section that is constructed from the High Zagros Fault to the Mountain Front Fault highlights the difference in the folding style across the area. The vertical and lateral changes in the style of the folding indicate the influence of mechano-stratigraphic contrast between the sedimentary units. Three main décollement levels (the basal Lower Palaeozoic, the intermediate Triassic, and the upper Upper Cretaceous–Lower Palaeocene) have been interpreted. Folds developed during the Zagros Fold–Thrust Belt evolution above and below these décollement horizons are decoupled from each other and are different in both geometry and size. Similarly, thickness and facies changes of some formations across the region cause lateral variation in folding pattern from the north to the south. Polyharmonic folds exist in the south, where the different structural levels are relatively strongly coupled. To the north, however, strongly disharmonic folding occurs where a combination of increased décollement thickness and decreased mechanical competence has led to decoupling at different structural levels. This change in folding style has a direct impact on hydrocarbon exploration in the area. To reduce structural risk in exploration, the incorporation of high-resolution deep seismic data with the surface geology is recommended for future hydrocarbon exploration activities within the Lurestan region.
Late Jurassic palaeoclimatic change from clay mineralogy and gamma-ray spectrometry of the Kimmeridge Clay, Dorset, UK
Authors: HESSELBO STEPHEN P. , DECONINCK JEAN-FRANÇOIS , HUGGETT JENNIFER M. , MORGANS-BELL HELEN S. 
Published: October 2009

Abstract:
The Late Jurassic was a time of increasing aridity in NW Europe. Here, a new clay mineral dataset is presented from a 600 m thick composite core through the Kimmeridge Clay Formation, southern England. Clay mineral assemblages comprise mainly illite and kaolinite, with minor randomly interstratified illite–smectite mixed-layer clays. SEM observations indicate that clay minerals are mainly detrital, except in silty strata of late Tithonian age, which contain abundant pore-filling kaolinite aggregates. Th/K ratios determined from gamma-ray spectrometry mirror palaeoclimatically significant variations in kaolinite/illite ratios, with notable exception where diagenetic kaolinite occurs. Comparison with age-equivalent strata identifies regional cyclic variations in clay minerals at the 100–300 m scale. Small-scale (10–20 m) variations in clay minerals and Th/K also occur. It is proposed that the region experienced progressively intense humidity through the Kimmeridgian, followed by a return to more arid conditions during the early Tithonian. Following a mid-Tithonian peak in aridity (the ‘Hudlestoni Event'), more humid climatic conditions returned prior to the development of latest Tithonian intense aridity. Late Jurassic climate was apparently subject to synchronously cyclic changes across a broad area of the Laurasian continent. Such changes could not have resulted from mountain building or continental rotations.

Supplementary material:

Clay data are available at
http://www.geolsoc.org.uk/SUP18376
.
Smothering of microbial mats by macrobiota: implications for the Ediacara biota
Authors: McILROY DUNCAN , BRASIER MARTIN D. , LANG ANDREW S. 
Published: October 2009

Abstract:

Recent advances in understanding the preservation of the soft-bodied Neoproterozoic Ediacara biota have centred upon the role of microbes in casting the morphologies of static or dead macrobiota on the Precambrian sea floor. This experimental study explores the preservational effects brought about by the passive movement of dead macro-organisms upon a pre-established marine microbial mat under laboratory conditions. This demonstrates the potential for making multiple impressions of body tissues on the surface of microbial mats by means of passive transport alone. This throws doubt on the evidence for active feeding in Ediacaran fossils such as
Dickinsonia
and
Yorgia
.

Supplementary material:

Methods are available at
http://www.geolsoc.org.uk/SUP18375
.
Infracambrian petroleum play elements of the NE Taoudenni Basin (Algeria)
Authors: Rahmani A. , Goucem A. , Boukhallat S. , Saadallah N. 
Published: October 2009

Abstract
The Taoudenni Basin, North Africa's largest sedimentary basin, is located in western Mauritania, northern Mali and southwestern Algeria. Of the four petroleum wildcat wells drilled to date, the Abolag-1 well, Mauritania, yielded gas shows in Infracambrian (Neoproterozoic) stromatolitic carbonates. We present details of the different plays of the basin from the Chenachène region in Algeria. The Infracambrian is generally composed of three sedimentary packages: a basal sandstone (a unit of the Douik Group), overlain by carbonates (the Hank Group), sandstones and shales (the Dar Echeikh Group). The play is sourced by Infracambrian organic-rich black shales. In neighbouring Mauritania these were penetrated by water wells and shallow boreholes, containing in places >20% TOC. In the Hank Group the best reservoirs are associated with fractured intervals. The Dar Echeikh Group includes several potential reservoir units with porosities of up to 26%. Potential petroleum trap types in the Algerian part of the Taoudenni Basin are associated with folds, the basal Palaeozoic unconformity, and Infracambrian and Triassic–Jurassic half-graben.
Neoproterozoic timescales and stratigraphy
Authors: Smith Alan G. 
Published: October 2009

Abstract
The Infracambrian is a term for mostly Neoproterozoic successions in North Africa and areas to the east. Its base lies within the middle Neoproterozoic period, or Cryogenian, includes the youngest Neoproterozoic period, or Ediacaran, and continues into the early Cambrian to the level at which trilobites first appear. The Cryogenian lacks any biostratigraphic zonation; and no global biostratigraphic schemes exist for the Ediacaran. The formal classification of the Neoproterozoic is currently under review.
The Cryogenian–Ediacaran (CE) interval includes at least three prominent diamictite horizons that are clearly linked to penecontemporaneous glaciations. The oldest is ‘Sturtian’, next oldest is ‘Marinoan’ (probably the most extensive), both names are Australian in origin but are used internationally. The Gaskiers glaciation is the youngest and probably the least extensive. There are important unresolved problems of the precise number, age, extent and nomenclature of the Neoproterozic glaciations in Australia.
Several palaeomagnetic poles in the age range 600–550 Ma place glacial deposits of that age range in Australia in tropical latitudes. These data, together with older poles from Laurentia, gave rise to the notion of the Snowball Earth, in which the Earth froze over completely, but the profound refrigeration required appears to have had very little effect on biological evolution.
Biostratigraphic zonation with the precision attainable throughout the Phanerozoic does not appear possible for the CE interval. Thus, most correlations are based on about 40 U–Pb and Re–Os dates. These confirm the existence of at least three glacial sequences (sequence is used here as an informal term), but it is possible that the Sturtian and Marinoan were essentially one glacial unit. Deglaciation was accompanied by the unique ‘cap carbonates’.

The glacial sequences all show a characteristic δ
13
C pattern, but present knowledge is inadequate to use these patterns for detailed global correlation. The most reliable chemostratigraphic correlations are likely to be based on strontium isotope variations.

Black shale horizons commonly follow deglaciation. A few basins produce Neoproterozoic hydrocarbons; others are potential producers. As a whole, the Neoproterozoic represents both a scientific and an exploration frontier.
Late Proterozoic plate tectonics and palaeogeography: a tale of two supercontinents, Rodinia and Pannotia
Authors: Scotese Christopher R. 
Published: October 2009

Abstract

The plate tectonic and palaeogeographic history of the late Proterozoic is a tale of two supercontinents: Rodinia and Pannotia. Rodinia formed during the Grenville Event (
c
. 1100 Ma) and remained intact until its collision with the Congo continent (800–750 Ma). This collision closed the southern part of the Mozambique Seaway, and triggered the break-up of Rodinia. The Panthalassic Ocean opened as the supercontinent of Rodinia split into a northern half (East Gondwana, Cathyasia and Cimmeria) and a southern half (Laurentia, Amazonia–NW Africa, Baltica, and Siberia). Over the next 150 Ma, North Rodinia rotated counter-clockwise over the North Pole, while South Rodinia rotated clockwise across the South Pole. In the latest Precambrian (650–550 Ma), the three Neoproterozoic continents – North Rodinia, South Rodinia and the Congo continents – collided during the Pan-Africa Event forming the second Neoproterozoic supercontinent, Pannotia (Greater Gondwanaland). Pan-African mountain building and the fall in sea level associated with the assembly of Pannotia may have triggered the extreme Ice House conditions that characterize the middle and late Neoproterozoic. Although the palaeogeographic maps presented here do not prohibit a Snowball Earth, the mapped extent of Neoproterozoic ice sheets favour a bipolar Ice House World with a broad expanse of ocean at the equator. Soon after it was assembled (
c
. 560 Ma), Pannotia broke apart into the four principal Palaeozoic continents: Laurentia (North America), Baltica (northern Europe), Siberia and Gondwana. The amalgamation and subsequent break-up of Pannotia may have triggered the ‘Cambrian Explosion’. The first economically important accumulations of hydrocarbons are from Neoproterozoic sources. The two major source rocks of this age (Nepa of Siberia and Huqf of Oman) occur in association with massive Neoproterozoic evaporite deposits and in the warm equatorial–subtropical belt, within 30° of the equator.
187
Re-
187
Os geochronology of Precambrian organic-rich sedimentary rocks
Authors: Kendall Brian , Creaser Robert A. , Selby David 
Published: October 2009

Abstract

Global correlations of Precambrian stratigraphic successions can be hampered by the coarse resolution of biostratigraphic and chemostratigraphic records, and by the scarcity of reliable U–Pb zircon age constraints. The development of the
187
Re (rhenium)–
187
Os (osmium) radioisotope system as an accurate deposition-age geochronometer for organic-rich sedimentary rocks (e.g. black shales) holds great potential for an improved radiometric calibration of the Precambrian rock record. Here, we review Re–Os isotope data obtained for Precambrian black shales and revisit the discrepancy in Re–Os ages for the Neoproterozoic Aralka Formation (central Australia). In addition, we introduce new Re–Os isotope data for the Late Neoproterozoic Doushantuo Formation (South China) that highlights the necessity of a rigorous sampling protocol for depositional age determinations. Improvements in sampling and analytical methodologies have permitted the determination of precise ages (<1%, 2σ) from Late Neoproterozoic to Late Archaean shales. Whole-rock digestion using a Cr
VI
–H
2
SO
4
solution minimizes the release of detrital Re and Os from shale matrices, and selectively attacks organic matter that hosts hydrogenous Re and Os. The Re–Os system in organic-rich sedimentary rocks appears to be robust during hydrocarbon maturation and up to the onset of lowermost greenschist facies metamorphism, but post-depositional hydrothermal fluid flow can result in scattered Re–Os isotope data. The Re–Os black shale geochronometer should find utility for constraining the age of a diverse range of Precambrian geological phenomena. In addition, the initial
187
Os/
188
Os composition determined from Re–Os isochron regressions serves as a tracer for the Os isotope composition of Precambrian sea water.
Neoproterozoic-Early Cambrian (Infracambrian) hydrocarbon prospectivity of North Africa: a synthesis
Authors: Lottaroli Fabio , Craig Jonathan , Thusu Bindra 
Published: October 2009

Abstract
Despite the existence of proven Neoproterozoic–Early Cambrian (‘Infracambrian’) hydrocarbon plays in many parts of the world, the Neoproterozoic Eon, from 1000 Ma to the base of the Cambrian at 542 Ma, is relatively poorly known from a petroleum perspective. The so-called ‘Peri-Gondwanan Margin’ is one region of the Neoproterozoic world that is exciting particular interest in the search for ‘old’ hydrocarbon plays, mainly due to exploration success in time-equivalent sequences of Oman. The ‘Infracambrian’ succession in North Africa is widely accessible, and is already emerging as a hydrocarbon exploration target with considerable potential and with proven petroleum systems in different areas. The Taoudenni Basin (Mauritania, Mali, Algeria) in western North Africa is an underexplored basin, despite the Abolag-1 well (Texaco 1974) gas discovery. New palynological data have recently provided the first definitive Late Riphean age dates for the stromatolitic limestone reservoir sequence in Abolag-1. The widespread presence of stromatolitic carbonate units of potential reservoir facies in many parts of North Africa has been confirmed by new fieldwork in the Taoudenni Basin, in the Anti-Atlas region of Morocco and in the Al Kufrah Basin of Libya. Similar biostratigraphic age constraints have also been obtained from subsurface sequences of the Cyrenaica Platform bordering the East Sirte Basin of Libya, many of which have been traditionally assigned an ‘unconstrained’ Cambro-Ordovician age on the basis of lithological characteristics. Besides the proven, producing, weathered-granite reservoir in East Sirte Basin, the hydrocarbon potential of Neoproterozoic–Early Cambrian sequences developed in structural troughs bordering the south Cyrenaica Platform is still being evalutated. Neoproterozoic–Early Cambrian organic-rich strata with hydrocarbon source rock potential are widespread along the Peri-Gondwanan Margin. Some of the black shales encountered on the West African Craton may be as old as 1000 Ma and predate the Pan-African orogenic event. The Late Ordovician–Early Silurian systems in North Africa and the Middle East may form a good analogue for post-glacial source rock depositional systems in the Neoproterozoic, where black shale deposition may also have been triggered by post-glacial sea-level rise.