bluuebunny/crossref_metadata_2025_split huggingface dataset:
40
Ar/
39
Ar constraints on obduction of the Seram ultramafic complex: consequences for the evolution of the southern Banda Sea
Authors: Linthout Kees , Helmers Henk , Wijbrans Jan R. , Van Wees Jan Diederik A. M. 
Published: April 2008

Abstract

On Kaibobo (W Seram), obduction of hot oceanic lithosphere produced high-grade metamorphism and granite in overthrust continental crust.
40
Ar/
39
Ar plateau ages of 5.65–6.0 Ma and 5.4 Ma of muscovite and biotite from the sole, among the youngest so far measured on single crystals, indicate complete resetting of the Ar-isotope system. Chloritized biotite crystals gave disturbed spectra and younger ages. Single fusion on biotite from the granite gave an age of 5.5 Ma. Time limits for the obduction-exhumation history of the Kaibobo complex and sole are approximated by simple 1D forward P-T-t modelling, constrained by PT data and
40
Ar/
39
Ar thermochronology (
c.
400°C at 6 Ma;
c.
320°C at 5.5 Ma). Best fit results indicate that the decelerating post-emplacement exhumation of ophiolite and sole began ≤ 8 Ma ago. The rate during the first 1 Ma of this uplift exceeded 7.5 mm a
−1
. Undoing 8 Ma of migration in the SW Pacific and Australian regimes of motion back-tracks Kaibobo to the site where obduction-emplacement ended: near the southeastern corner of the Banda Sea plate. Similar compositions and time-settings of the Kaibobo and N Timor ophiolites lead us to postulate that, during the Early Miocene, slow-rate spreading occurred in the oceanic lithosphere of the southern Banda Sea, south of the current volcanic arc.
The geology and tectonic evolution of the Bacan region, east Indonesia
Authors: Malaihollo Jeffrey F. A. , Hall Robert 
Published: April 2008

Abstract
Bacan is located in the zone of convergence between the Eurasian, Philippine Sea and Australian plates. The oldest rocks in Bacan belong to the Sibela Continental Suite and are probably of Precambrian age. The complex includes continental phyllites, schists and gneisses of upper amphibolite facies. Isotopic dating yielded extremely young ages due to interaction with hydrothermal fluids. Juxtaposed against the continental rocks is the mostly unmetamorphosed, arc-related Sibela ophiolite, probably derived from the Philippine Sea plate. Isotopic dating yielded a Cretaceous age with an Oligocene-Miocene overprint. In north Bacan, the oldest formation is the Upper Eocene Bacan Formation which comprises interbedded arc volcanic and turbiditic volcaniclastic rocks, metamorphosed under conditions between the prehnite-pumpellyite and greenschist facies. A similar Lower Miocene sequence, assigned to the same formation, is exposed in south Bacan. The Oligocene Tawali Formation on Kasiruta, NW of Bacan, consists of arc basalts and volcaniclastic turbidites, metamorphosed to zeolite facies. The Bacan and Tawali Formations represent different parts of an arc, active from Late Eocene until Early Miocene, resulting from northward subduction of the Australian plate under the Philippine Sea plate. There is a major Lower Miocene unconformity, representing collision of the Australian continent with the Philippine Sea plate, above which shallow marine limestones of the Lower-Middle Miocene Ruta Formation were deposited. This deposition was interrupted by sudden influxes of volcaniclastic sands, forming the Amasing Formation. The Upper Miocene-Pleistocene Kaputusan Formation, rests locally unconformably on older rocks, and includes three members. The Goro-goro Member consists of arc andesites, originating from four eruption centres, which erupted from Late Miocene to Pleistocene, with the oldest in south and the youngest in north Bacan. The Pacitak Member consists of shallow marine pyroclastic rocks. The Mandioli Member formed fringing coastal reef limestones. The volcanic rocks of this formation were produced by eastward subduction of the Molucca Sea plate. Quaternary basalts are related to movement along the Sorong fault. It is concluded that most of the Bacan region has been part of the Philippine Sea plate since the Cretaceous; volcanic rocks of different ages all have an arc character and chemistry, and lithological variations reflect different positions within the volcanic arc; and there is evidence for continental crust of Australian origin in the Bacan area by the Early Miocene.
Gondwana origin of the Baoshan and Tengchong terranes of west Yunnan
Authors: Wopfner Helmut 
Published: April 2008

AbstractUpper Palaeozoic glaciomarine deposits combined with the presence of cold-water faunas andGlossopterisindicate a Gondwana provenance of the Baoshan and Tengchong Blocks in western Yunnan. The glacial origin of these Permo-Carboniferous deposits is verified by a three-fold subdivision of the basal sequence comprising, in ascending order: diamictites with faceted and striated clasts, laminites with dropstones, and a black anaerobic de-glaciation facies. The succeeding carbonates of the upper Permian and Lower Triassic originated during a post-glacial phase of a much warmer climate. Although the two blocks are adjacent to each other their Upper Palaeozoic sequences show significant differences. The glacigene successions of the Baoshan Block are comparatively thin and are overlain by thick basalts and red beds. On the Tengchong Block the glacigene marine deposits exceed 1000 m and are followed by thick reefal limestones of Lower Permian age. An active volcanic rift setting is suggested for the Baoshan Block and a proximal passive margin environment at a somewhat lower latitude for the Tengchong Block. The succession of the latter is comparable with Permo-Carboniferous sections in NW Australia, especially that of the Bonaparte Gulf basin, and it is assigned to the Sibumasu tectono-stratigraphic unit. The Baoshan sequence shows similarities to sequences of Tibet and NE India and is therefore assigned to the Tibetan realm. Both terranes separated from Gondwana in the late Early Permian. Docking commenced in the Late Triassic concomitant with the closure of the Changning-Menglian Belt. Lateral displacements in the course of the Himalayan orogeny moved the Tengchong Block north, bringing it into juxtaposition with the western margin of the Baoshan Block. This tectonic contact is now the Nujiang Line.
Early Mesozoic orogeny in Fujian, southeast China
Authors: Zhou Zuyi , Lao Qiuyuan , Chen Huanjiang , Ding Sijiang , Liao Zhongting 
Published: April 2008

Abstract
The Mesozoic sedimentary successions of west Fujian evolved from Lower Triassic deep marine fine turbidites to Upper Triassic and Jurassic coal-bearing molasse deposits, and represent a typical foreland basin sedimentary sequence. This foreland basin was generated by an early Mesozoic continental collision to the south, between the South China block and the South China Sea block. This collision led to the formation of Permo-Triassic S-type granites, and a first stage of thrusting in a NNW-SSE direction. Post-collisional convergence resulted in the accumulation of thick molasse deposits. Two main unconformities, within the molasse and separating the molasse from the underlying flysch, necessitate a re-evaluation of the traditional concepts of ‘Indosinian’ and ‘Yanshanian’ movements in SE China. The tectonic and stratigraphic evolution of the west Fujian foreland basin, together with the structural features in the basin, show that the Early Mesozoic orogeny in the region was a mild and continuous process.
Metal-organic interactions in the Dinantian Solway Basin, UK: inferences for oil migration studies
Authors: Veale C. , Parnell J. 
Published: April 2008

Abstract
Carboniferous basins within the British Isles show a variety of metal-organic fluid interactions, including the precipitation of thoriferous bitumen nodules. These represent the interaction between a thorium-rich fluid, such as groundwater, and migrating hydrocarbons. They are found in the Dinantian of the Northwest Irish Basin and the Solway Basin. In the latter case, nodules are found in coarse-grained clastics laid down in a variety of depositional environments. The source of the thorium was the nearby Caledonian Criffel-Dalbeattie Granite. Studies of sedimentological parameters of both nodule-bearing and barren beds, and the structure of the basin, show that factors controlling the distribution of nodules include the maturity and porosity of the host rock, with an enhanced maturity and high porosity preferable, as well as the depositional environment. In the case of the Dinantian of the Solway Basin, distal shallow-marine sediments and channelized deposits host the nodules. Chemical age dating of the thoriferous inclusions within the nodules points to the possible use of these nodules in assessing the timing as well as spatial distribution of hydrocarbon migration within sedimentary basins. Results indicate a correlation with previous models of Mesozoic hydrocarbon migration.
Biotic gradients on a homoclinal ramp: the Alamogordo Member of the Lake Valley Formation, Lower Mississippian, New Mexico, USA
Authors: Jeffery David L. , Stanton Robert J. 
Published: April 2008

Abstract

The Lower Mississippian Alamogordo Member of the Lake Valley Formation in south-central New Mexico represents a well exposed carbonate-dominated homoclinal ramp with little evidence of sediment transport. Biotic components present and evident in thin section have distinct distributions in the level-bottom facies in relation to their shoreward and basinward ramp positions. Assemblages (I–IV) are established along the depth gradient from shallow to deep water, and are useful in palaeobathymetric interpretation; they are similar in composition to the depth-related phases recognized in Dinantian mounds by Lees & Miller (1985). The biotic assemblages shift laterally in successive beds of the Alamogordo Member, indicating variations in sea level during deposition. As a result, deepening and successive shallowing during a transgressive-regressive cycle can be tracked within the Alamogordo Member. The ramp slope is interpreted to have been of the order of 0.5°, based on the maximum depths for green and red algae having been 110m and 250m respectively. The systematic positions of several problematical taxa (
Asphaltinella, Sphaerinvia
, stacheiins and salebrids) are discussed.
Late Viséan buildups at Kingscourt, Ireland: possible precursors for Upper Carboniferous bioherms
Authors: Somerville Ian D. , Strogen Peter , Jones Gareth LL. , Somerville H. E. Anne 
Published: April 2008

Abstract

Two late Viséan (Asbian-early Brigantian) buildup complexes occur in the Kingscourt Outlier in Ireland, near the top of the Mullaghfin Formation, a shallow-water, grainstone unit. These massive buildups at Ardagh and Cregg accumulated on the margins of a carbonate platform bordering a deep-water basin. Both have a buildup facies of fine-grained, peloid-rich, algal lime mudstones and wackestones, interbedded with coarser grained intraclastic, skeletal packstones and grainstones (interbuildup facies). Microbial structures are well developed in the buildup facies, principally domal stromatolites, thrombolites and oncoidal fabrics of cyanophytes (
Ortonella
and
Girvanella
) with encrusting formainifers (
Aphralysia
and
Textrataxis
). Algal structures include rhodoliths (
Solenopora
) and fragments of
Ungdarella
and stacheiids, with less abundant chlorophytes (
Koninckopora
); in the interbuildup facies,
Koninckopora
is more abundant.

Near the top of the Ardagh buildup is an unusual development of phylloid algal boundstone composed of the possible ancestral coralline red alga
Archaeolithophyllum
. This boundstone also contains encrusting bryozoans and foraminifers, and directly overlies abundant Brigantian
in situ
fasciculate rugose corals. This upper unit appears to be associated with a rapid shallowing event, which stimulated the development of a wave-resistant rigid framework.

Laterally, bedded intraclastic skeletal packstones and grainstones, with thin interbedded clays and shales, pass into the lower part of the massive Ardagh buildup, but appear to onlap and drape the upper part of the buildup. Buildup clasts occur within the interbuildup facies and proximal flank facies, indicating synsedimentary cementation.

Late Viséan buildups of the Ardagh type highlight an important period of diversification of colonial rugose corals and calcareous algae associated with the development of widespread shallow-water carbonate platforms worldwide. This allowed the emergence of new algal groups, particularly the red algae (
Archaeolithophyllum
and
Ungdarella
) and the palaeoberesellid green algae (
Kamaenella
), which subsequently dominated Upper Carboniferous wave-resistant bioherms.
Evidence for catastrophism at the Famennian-Dinantian boundary in the Iberian Pyrite Belt
Authors: Moreno Carmen , Sierra Sonia , Sáez Reinaldo 
Published: April 2008

Abstract
Terrigenous shelf sedimentation during the Devonian created a homogeneous basin in the Iberian Pyrite Belt. This shallow south-Iberic basin changed into a mosaic of horsts and graben at the Famennian-Dinantian boundary and subsequent evolutionary history can be explained in terms of locally increased rates of subsidence. Deposits commonly related to highly energetic processes characterize this change (fan-deltas, sediment gravity flows, rapid basin-shallowing). These resulted from convulsive/catastrophic events related to the Bretonic phase of the Hercynian Orogeny.
The stratigraphy and cyclicity of the late Dinantian platform carbonates in parts of southern and western Ireland
Authors: Gallagher Stephen J. 
Published: April 2008

Abstract

The late Dinantian platform carbonate successions of the Burren, Buttevant and Callan areas in Ireland have been correlated using detailed litho- and biostratigraphy. Several subdivisions or lithofacies associations (LA) of the Asbian to Brigantian part of the succession have been recognized in each area (lithofacies associations 1–5). Holkerian(?) to early Asbian ramp carbonates of LA 1 underlie the late Asbian successions in both the Burren and Buttevant areas. The influx of the bilaminar palaeotextulariid
Cribrostomum lecomptei
coincides with the onset of late Asbian shallow-marine cyclic platform sedimentation (LA 2) in all areas. The sediments of LA 2 have abundant
Kamaenella
and foraminifera, and are characterized by palaeokarstic surfaces and shales that cap a minimum of nine shallowing-upward minor cycles in the Burren and Buttevant areas. Two new biostratigraphic subdivisions (Cf6γ1 and Cf6γ2) of the late Asbian/Cf6γ subzone are described for the first time in this part of the succession. Brigantian sedimentation (LA 3) is typified by amalgamated beds of crinoidal limestone and abundant Asteroarchaediscidae. Thin peloidal limestones with coral thickets cap shallowing-upward cycles within this succession. These cycles, which are thinner and less numerous than those of the underlying late Asbian, rarely terminated in emergence, but most reached shallow subtidal depths prior to the next transgression. The change in cyclicity style across the Asbian/Brigantian boundary may be related to the sedimentation rates of the crinoidal limestones, due to increases in cyclic oscillation in the Brigantian. Brigantian LA 4 is characterized by deep subtidal cherty limestones, with abundant algal-coated wackestone intraclasts.
Fasciella
and
Howchinia bradyana
are typical microfossils. No cyclicity is observed, probably owing to the deep subtidal nature of this unit. LA 4 is overlain by another unit of cyclic crinoidal limestones (LA 5) in the Burren, which has no correlatives in the other areas studied. The succession in all areas is unconformably overlain by Namurian siliciclastic rocks. The nature and number of minor cycles in the late Dinantian of Ireland is similar to those of platform successions of the same age elsewhere in the British Isles, suggesting that eustatic changes were one of the major controls on cyclicity during the late Dinantian.
Controls on ramp, platform and basinal sedimentation in the Dinantian of the Dublin Basin and Shannon Trough, Ireland
Authors: Strogen P. , Somerville I. D. , Pickard N. A. H. , Jones G. LL. , Fleming M. 
Published: April 2008

Abstract
In the Dublin Basin a Courceyan ramp phase of sedimentation was followed in the Chadian by tectonic break-up of the basin into distinct shallow-water platforms, on which production of carbonate sediments continued in considerable volume, and ‘deep’ basinal areas in which it ceased. Progradation of the platforms across these basinal areas was limited, and mainly confined to the dip-slope of hanging wall blocks; progradation across fault scarps was rare. In the Shannon Trough basement-fault control was evident in the distribution and migration patterns of volcanic centres in the Chadian to Arundian, but despite this, ramp sedimentation occurred throughout the Dinantian, evolving into a purely constructional large platform by late Dinantian time. There was no break-up of the basin as in the case of the Dublin Basin.
The reason for the contrasting behaviour of the two basins is related to the rate of upwards movement of extensional faults relative to sedimentation rates. In the Dublin Basin these faults penetrated to the palaeosurface to form scarps by the late Chadian, and this topography survived into the Brigantian. In the Shannon Trough these faults failed to surface, but deep basement structures controlled the distribution of Dinantian volcanic centres which lie on a series of ENE-trending lineaments. These lineaments, which parallel the axis of the Shannon Trough, almost certainly mark the traces of active down-to-basin faults that controlled its half-graben structure.
The basement rocks of the two basins are clearly of a different nature; the Dublin Basin is floored by basement of a much more heterogeneous nature than the Shannon Trough, the former lying south and the latter north of the putative Iapetus Suture line.
Siliceous rocks of the Culm Basin, Germany
Authors: Gursky Hans-Jürgen 
Published: April 2008

Abstract
The classic Dinantian cherts of the Rhenish Massif and Harz Mountains, Germany, were analysed for their petrography and sedimentology. They occur in five lithostratigraphic units: the Lower Alum Shale Formation, the Black Chert Formation, the Pale Chert Formation, the Siliceous Limestone Formation, and the Siliceous Transitional Formation (upper Hastarian to Asbian, CuII to CuIIIα of the German cephalopod zonation). Mafic volcanic rocks are locally associated with these strata. Four regional facies zones have been defined.
Radiolarian chert, spiculitic chert, homogeneous chert, and silicified quartz-trachytic tephra and tuffite are the main chert types. These mostly form current-laminated grey, black, greenish or reddish beds rhythmically alternating with layers of siliceous mudstone and, in places, variably intercalated with grey and black mudstones and siltstones, phosphorites, metabentonites, limestone turbidites, greywackes and quartz arenites. The siliceous rocks were deposited in a moderately deep (upper bathyal) strait of an equatorial sea that was part of palaeo-Tethys. Westward-driven nutrient-rich currents from the palaeo-Pacific Ocean favoured high radiolarian fertility. Relatively pure biosiliceous ooze was deposited under temporarily anoxic conditions when, due to dry climate and high sea-level, detrital input decreased.
Deposition of the siliceous facies ended with increased detrital input and breakdown of the ocean-current system due to the collision of Laurasia and Gondwana during the Variscan Orogeny.
Reconstruction of a lost carbonate platform on the shelf of Fennosarmatia: evidence from Viséan polymictic debrites, Holy Cross Mountains, Poland
Authors: Belka Zdzislaw , Skompski Stanislaw , Sobon-Podgorska Janina 
Published: April 2008

Abstract
The sedimentary sequence of a totally eroded carbonate platform on the shelf of Fennosarmatia in Poland has been reconstructed based on the analysis of detrital material derived from the platform and deposited in an adjacent basin. The database was taken from a polymictic debrite unit intercalated in the Viséan basinal succession exposed in the southwestern Holy Cross Mountains. The unit represents a gravity-flow deposit and contains carbonate clasts ranging from Frasnian to Viséan in age. They provide evidence for a Frasnian carbonate platform located south of the Holy Cross area that drowned during Famennian and Tournaisian times but subsequently, during the early Viséan, started to recover. This reversed trend is interpreted to have resulted from the combined effect of eustatic sea level fall and tectonic uplift. The geographical extent of the inferred carbonate platform system, named here as the Nida Platform, cannot be precisely outlined, but most probably corresponded with the Jedrzejow High, an elevated fragment of Precambrian basement.
Cyclic stratigraphy, facies and fauna of the Lower Carboniferous (Dinantian) of the Moscow Syneclise and Voronezh Anteclise
Authors: Makhlina Mariya KH. 
Published: April 2008

Abstract
On the basis of sedimentological investigation of rocks, together with bed-by-bed studies of foraminifers, conodonts and spores, rhythmic sedimentation has been demonstrated in the Lower Carboniferous of the Moscow Syneclise and Voronezh Anteclise. Cycles of different order have been established using the methods of rhythmic stratigraphy elaborated by Tikhomirov. Four transgressive-regressive cycles of the sixth order have been recognized in the Dinantian of the Russian Platform. The latter are time-stratigraphic equivalents of the newly proposed stages of the Khaninian and Shurinovkian in the Tournaisian, and Kozhimian and Okian Stages in the Viséan. Each of these cycles includes two or three smaller cycles which represent the initial and maximum transgressive units and a regressive unit.
Sequence biostratigraphy of the Tournaisian-Lower Viséan rocks of the Russian Platform
Authors: Rukina G. A. 
Published: April 2008

Abstract
A statistical analysis of foraminiferal communities was used to study Tournaisian to lowermost Viséan rocks of the Moscow Syneclise, Voronezh Anteclise, Volga-Urals region and the northern part of the Pre-Caspian Depression. Eleven levels of foraminiferal community reorganizations were recognized and traced over the Russian Platform. These levels correspond to changes in foraminiferal dominance which often coincide with changes in lithology and thus reflect an environmental sequence. An understanding of regional events affecting the sedimentary basin, including foraminiferal reorganizations, leads to more precise correlation of depositional sequences from one area to another.