PALYNOLOGIC CONTRIBUTIONS TO PETROLEUM EXPLORATION IN THE PERMIAN FORMATIONS OF THE COOPER BASIN, AUSTRALIA

1969 ◽  
Vol 9 (1) ◽  
pp. 79
Author(s):  
R. J. Paten
Keyword(s):  
Petroleum Exploration ◽  
Upper Permian ◽  
Lower Permian ◽  
Hydrocarbon Accumulation ◽  
Early Permian ◽  
Sufficient Data ◽  
Spores And Pollen ◽  
Eastern Australia ◽  
Biostratigraphic Subdivision ◽  
Cooper Basin

From 1959, when Permian spores and pollen were first identified from Delhi-Santos wells in the Cooper basin until 1967, appreciation of the palynologic succession was impeded by problems associated with the severe carbonization of the microfossils. By 1966, sufficient data had been accumulated for the elucidation of the broad palynologic framework. The Merrimelia Formation was identified as early Permian (palynologic unit Plb of Evans), the Lower and Middle Members of the Gidgealpa Formation as Lower Permian (units Plc-P3a) and the Upper Member of the Formation as Upper Permian (units P3b-P4). Breaks in the microfloral succession were noted above the Merrimelia Formation and between the Middle and Upper Members of the Gidgealpa Formation corresponding with observed litho-stratigraphic hiatuses.Well-preserved microfloras were recovered from four wells in late 1967 and early 1968, and produced a dramatic advance in knowledge of the Permian biostratigraphy. It became possible to relate the microfloral succession to the Permian palynologic stages proposed by Evans (1967), for eastern Australia. The Merrimelia Formation was referred to stage 2, while stages 3, 4 and 5 were recognised within the Gidgealpa Formation. In addition, two units of apparently short duration were recognised in each of stages 4 and 5. A six-fold biostratigraphic subdivision of the entire Permian sequence was thus possible.Palynology is finding wide application to problems encountered in current drilling and stratigraphic investigations. It has shown particular value when applied to those problems associated with the mid-Gidgealpa Formation disconformity, which is an important feature relative to hydrocarbon accumulation in the Gidgealpa Field.

THE GEOLOGY OF THE PALCHAWARRA AREA COOPER BASIN

1972 ◽  
Vol 12 (1) ◽  
pp. 53 ◽  
Author(s):  
A.J. Kapel
Keyword(s):  
Upper Permian ◽  
Lower Permian ◽  
Western Boundary ◽  
Early Permian ◽  
Eastern Boundary ◽  
Cooper Basin

This paper is another chapter in the long series of papers presented to APEA Conferences since 1964 on the geology of the Cooper Basin. The Patchawarra area became of interest after Bridge Oil on behalf of its partners discovered oil in the area while drilling Tirrawarra No. 1 as part of their obligations to earn a 50 percent interest in the area. This paper deals with the central part of the Patchawarra Gravity Low first described by the Author in 1966.The Tirrawarra Formation was deposited in the Patchawarra trough during early Permian. The Gidgealpa Innamincka trend constitutes the eastern boundary of this trough while the western boundary of the Patchawarra Gravity Low coincides with the western boundary of the Cooper Basin.Sedimentation during the Permian in the Cooper Basin is controlled regionally by the major structural trends such as, the Gidgealpa Innamincka Trend, but hiatii and minor local unconformities also developed around individual structrues.The major unconformity recognised in the Patchawarra Low occurs between the Upper Permian Toolachee Formation and the Lower Permian Moomba Formation.

SIMPSON DESERT SUB-BASIN—A PROMISING PERMIAN TARGET

1973 ◽  
Vol 13 (1) ◽  
pp. 33
Author(s):  
George E. Williams
Keyword(s):  
Lower Jurassic ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Seismic Exploration ◽  
Upper Permian ◽  
Lower Permian ◽  
Geophysical Surveys ◽  
Carbonaceous Shales ◽  
Cap Rock ◽  
Simpson Desert

Sediments of three major basins occur in the Simpson Desert region of central Australia:Cambro -Ordovician dolomites and sandstones, and Siluro- Devonian conglomerates, sandstones and shales, related to the Amadeus Basin:Permian conglomerates, sandstones, shales and coals of the Simpson Desert Sub-basin, the extensive eastern lobe of the Pedirka Basin:Mesozoic sandstones and shales of the Eromanga Basin.Principal petroleum exploration interest is presently directed toward the Permian sediments, which have many features in common with the petroleum producing Permian section of the neighbouring Cooper Basin.Lower Permian sediments known from drilling in the Simpson Desert Sub-basin comprise glaciofluvial conglomerates and sandstones overlain by fluvial and lacustrine sandstones, silt-stones, shales and coals. The maximum thickness encountered in wells is 1,479 ft (448 m) in Mokari 1.Recent seismic exploration 50 to 100 mi (80-160 km) west of Poeppel Corner in the deeper part of the Simpson Desert Sub-basin indicates that an additional sediment package up to 1,500 ft (350 m) thick occurs at depths of 6,500 to 7,500 ft (2,000-2,300 m) between Lower Permian and Lower Jurassic sections. This sediment package, nowhere penetrated by drilling, may be Middle to Upper Permian and/or Triassic in age. It is of great significance to petroleum exploration in the sub-basin and substantially upgrades the hydrocarbon prospects of the region.Permian sediments in the Simpson Desert Sub-basin thin by onlap, wedge out and stripping over the crests of anticlinal growth structures. Crestal sediments probably comprise mainly porous sandstones, grading off-structure into thicker sequences containing carbonaceous shales and coals. Such carbonaceous potential source rocks are probably best developed in the deepest part of the sub-basin, where Triassic cap rock may also be present. Two particularly promising drilling targets—the Colson Anticline and the East Colson Anticline—have been revealed by recent geophysical surveys in this portion of the sub-basin. Wells drilled on these structures may intersect Permo-Triassic sediments up to 2,200 + ft (670 in) thick which are comparable in age and type with producing sections in the Cooper Basin.

PETROLEUM SYSTEMS IN TASMANIA'S FRONTIER ONSHORE BASINS

2000 ◽  
Vol 40 (1) ◽  
pp. 26
Author(s):  
M.R. Bendall C.F. Burrett ◽  
H.J. Askin
Keyword(s):  
Oil And Gas ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Late Triassic ◽  
Upper Permian ◽  
Lower Permian ◽  
Peak Oil ◽  
Petroleum Systems ◽  
Upper Proterozoic ◽  
Oil Seep

Sedimentary successions belonging to three petroleum su persy stems can be recognised in and below the Late Carboniferous to Late Triassic onshore Tasmania Basin. These are the Centralian, Larapintine and Gondwanan. The oldest (Centralian) is poorly known and contains possible mature source rocks in Upper Proterozoic dolomites. The Larapintine 2 system is represented by rocks of the Devonian fold and thrust belt beneath the Tasmania Basin. Potential source rocks are micrites and shales within the 1.8 km-thick tropical Ordovician Gordon Group carbonates. Conodont CAI plots show that the Gordon Group lies in the oil and gas windows over most of central Tasmania and probably under much of the Tasmania Basin. Potential reservoirs are the upper reefal parts of the Gordon Group, paleokarsted surfaces within the Gordon Group and the overlying sandstones of the Siluro-Devonian Tiger Range and Eldon Groups. Seal rocks include shales within the Siluro-Devonian and Upper Carboniferous-Permian tillites and shales.The Gondwanan supersystem is the most promising supersystem for petroleum exploration within the onshore Tasmania Basin. It is divided into two petroleum systems— the Early Permian Gondwanan 1 system, and the Late Permian to Triassic Gondwanan 2 system. Excellent source rocks occur in the marine Tasmanite Oil Shale and other sections within the Lower Permian Woody Island and Quamby Formations of the Gondwanan 1 system and within coals and freshwater oil shales of the Gondwanan 2 system. These sources are within the oil and gas windows across most of the basin and probably reached peak oil generation at about 100 Ma. An oil seep, sourced from a Tasmanites-rich, anoxic shale, is found within Jurassic dolerite 40 km WSW of Hobart. Potential Gondwanan 1 reservoirs are the glaciofluvial Faulkner Group sandstones and sandstones and limestones within the overlying parts of the glaciomarine Permian sequence. The Upper Permian Ferntree Mudstone Formation provides an effective regional seal. Potential Gondwanan 2 reservoirs are the sandstones of the Upper Permian to Norian Upper Parmeener Supergroup. Traps consisting of domes, anticlines and faults were formed probably during the Early Cretaceous. Preliminary interpretation of a short AGSO seismic profile in the Tasmania Basin shows that, contrary to earlier belief, structures can be mapped beneath extensive and thick (300 m) sills of Jurassic dolerite. In addition, the total section of Gondwana to Upper Proterozoic to Triassic sediments appears to be in excess of 8,500 m. These recent studies, analysis of the oil seep and drilling results show that the Tasmanian source rocks have generated both oil and gas. The Tasmania Basin is considered prospective for both petroleum and helium and is comparable in size and stratigraphy to other glaciomarine-terrestrial Gondwanan basins such as the South Oman and Cooper Basins.

First basal synapsids (“pelycosaurs”) from the Upper Permian-?Lower Triassic of Uruguay, South America

2003 ◽  
Vol 77 (2) ◽  
pp. 389-392 ◽  
Author(s):  
Graciela Piñeiro ◽  
Mariano Verde ◽  
Martín Ubilla ◽  
Jorge Ferigolo
Keyword(s):  
South Africa ◽  
North America ◽  
South America ◽  
Lower Triassic ◽  
Late Carboniferous ◽  
Upper Permian ◽  
Lower Permian ◽  
Late Permian ◽  
Early Permian ◽  
Continental Deposits

In their monograph Review of the Pelycosauria, Romer and Price (1940), proposed that the earliest synapsids (“pelycosaurs”) were cosmopolitan, despite the observation that amniotes appeared to be restricted to the paleotropics during the Late Carboniferous and Early Permian (290–282 Ma). Romer and Price (1940) accounted for the scarcity of terrestrial tetrapods, including “pelycosaurs,” in Lower Permian beds elsewhere to the absence of coeval continental deposits beyond North America and Europe. Indeed, most workers recognized a geographical and temporal gap between Permo-Carboniferous “pelycosaurs” and therapsid synapsids. Recent research has confirmed that varanopid and caseid “pelycosaurs” were components of therapsid-dominated Late Permian faunas preserved in Russia and South-Africa (Tatarinov and Eremina, 1975; Reisz, 1986; Reisz et al., 1998; Reisz and Berman, 2001).

scholarly journals Initiation of petroleum exploration in Jameson Land, East Greenland

1986 ◽  
Vol 128 ◽  
pp. 103-121
Author(s):  
F Surlyk ◽  
S Piasecki ◽  
F Rolle
Keyword(s):  
Lower Triassic ◽  
Scientific Work ◽  
Upper Jurassic ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Upper Permian ◽  
Lower Permian ◽  
Western Basin ◽  
East Greenland ◽  
Promising Source

Active petroleum exploration in East Greenland is of fairly recent date and was preceded by a much longer history of scientific work and mineral exploration. The discovery in 1948 of lead-zinc mineralisation at Mestersvig resulted in the formation of Nordisk Mineselskab AIS in 1952. In the beginning of the seventies Nordisk Mineselskab initiated cooperation with the American oil company Atlantic Richfield (ARCO) in order to undertake petroleum exploration in Jameson Land. The Jameson Land basin contains a very thick Upper Palaeozoic - Mesozoic sedimentary sequence. Important potential source rocks are Lower Permian lacustrine mudstone, Upper Permian black marine mudstone, Middle Triassic dark marine limestone, uppermost Triassic black marginal marine mudstone, Lower Jurassic black mudstone and Upper Jurassic deep shelf black mudstone. Tbe Upper Permian mudstone, which is the most promising source rock, is immature to weakly mature along the western basin margin and is expected to be in the oil or gas-generating zone when deeply buried in the central part of the basin. Potential reservoir rocks include Upper Permian bank and mound limestones, uppermost Permian fan delta sandstones, Lower Triassic aeolian and braided river sandstones, and Lower, Middle and Upper Jurassic sandstones. The most important trap types are expected to be stratigraphic, such as Upper Permian limestone bodies, or combination stratigraphic-structural such as uppermost Permian or Lower Triassic sandstones in Early Triassic tilted fault blocks. In the offshore areas additional play types are probably to be found in tilted Jurassic fault blocks containing thick Lower, Middle and Upper Jurassic sandstones and lowermost Cretaceous sandstones and conglomerates. The recognition of the potential of the Upper Permian in petroleum exploration in East Greenland has important implications for petroleum exploration on the Norwegian shelf.

Re-evaluation of depositional models for the lower Permian Patchawarra Formation, Cooper Basin, South Australia: implications for petroleum exploration

2020 ◽  
Vol 60 (2) ◽  
pp. 794
Author(s):  
Carmine Wainman ◽  
Peter McCabe
Keyword(s):  
Cold Water ◽  
South Australia ◽  
Petroleum Exploration ◽  
Lower Permian ◽  
Time Intervals ◽  
Fine Grained ◽  
Coal Beds ◽  
Hyperpycnal Flows ◽  
Lenticular Bedding ◽  
Cooper Basin

The Late Carboniferous–Triassic Cooper Basin is Australia’s most prolific onshore petroleum province. The lower Permian Patchawarra Formation, which is up to 680 m thick and consists of up to 10% coal, is a major exploration target in the basin. Eighteen cores through the formation have been logged to re-evaluate the existing fluviolacustrine depositional model. The siliciclastics form fining- and coarsening-upward sequences that are 1–10 m thick. They are predominately fine-grained with abundant lenticular bedding, wavy bedding and thinly interlaminated siltstones and clays resembling varves. Granules and pebbles, interpreted as dropstones, are present throughout the formation. Coal beds are up to 60 m thick and rich in inertinite. Other than the coal beds, there is little evidence of the establishment of terrestrial conditions: roots are rare and there are no siliciclastic palaeosols. The siliciclastics are interpreted as the deposits of a large glaciolacustrine system, with the fining-upward successions deposited in subaqueous channels cut by hyperpycnal flows and the coarsening-upward successions deposited as overbank splays between those channels. Hyperpycnal flows may have resulted from sediment-laden cold water emanating from glacially-fed rivers, similar to those seen in many large glacial lakes in high latitudes and altitudes today. Much of the coal is interpreted as the accumulation of peats from floating mires that covered large parts of the glaciolacustrine system at certain time intervals. The high inertinite content of many coals is interpreted as the decay of organic matter within the floating mire. These new interpretations have the potential to enhance reservoir characterisation within the basin.

PROSPECTIVITY OF THE OFFSHORE SYDNEY BASIN: A NEW PERSPECTIVE

1998 ◽  
Vol 38 (1) ◽  
pp. 68 ◽  
Author(s):  
J.D. Alder ◽  
S. Hawley ◽  
T. Maung ◽  
J. Scott ◽  
R.D. Shaw ◽  
...  
Keyword(s):  
Petroleum Exploration ◽  
Sediment Provenance ◽  
Rift System ◽  
Lower Permian ◽  
Structural Development ◽  
Late Permian ◽  
Early Permian ◽  
Marine Transgression ◽  
Eastern Margin ◽  
Tasman Sea

Approximately 40 per cent of the 52,000 km2 Sydney Basin lies in shallow waters (less than 200 m) off the central New South Wales coast. Containing more than 5,000 m of Permo-Triassic marine and non-marine sediments, and having been the subject of several previous exploration campaigns, no wells have been drilled in the offshore despite widespread numerous occurrences of oil and gas onshore.The Sydney Basin, together with the Bowen and Gunnedah basins, form a major longitudinal Permo-Triassic basinal complex stretching 2,500 km down the eastern margin of Australia. Whereas the onset of this basinal development may have been extensional, reinterpretation of seismic and other geophysical data highlight the potential role played in the early development of the Sydney Basin by easterly directed compression. A compressional style is to be contrasted with the dominantly extensional style interpreted by others for the adjacent onshore areas. The most conspicuous structural element in the offshore, the Offshore Uplift, is interpreted to represent the western overthrust edge of the Currarong Orogen. Accepting the Panthalassan margin geometry of Veevers and Powell (1994) it follows that the Offshore Uplift and restored Dampier Ridge would have constituted a 'greater Currarong Orogen'. A series of progressive westerly directed thrust fronts may have been established across the Panthalassan margin, including the uplifted western margin of the Currarong Orogen, which over-rode and created a thrust load onto the eastern margin of the Lachlan Fold Belt. Much of the Early Permian development of the Sydney Basin therefore could have resulted as a consequence of foreland loading. This is consistent with depositional trends including the overall westerly directed marine transgression which dominated the sedimentary record of the Early Permian. Alternatively, this marine transgression may represent the sag phase induced along a segment of the Bowen-Sydney rift system that had been offset by the Hunter River Transverse Zone from the Gunnedah Basin to a site coincident with the Offshore Syncline.Previous interpretations identified structural development of the Currarong Orogen as either a Cretaceous (Tasman Sea rift related) or Middle to Late Permian phenomena. Early Permian structural growth of the offshore Uplift has important implications for petroleum exploration. The major impediment to exploration appears to be the perception that the Sydney Basin lacks suitable reservoir targets and is gas-prone. Potential source and seal sequences occur extensively within both Early Permian marine shales and siltstones and Early and Late Permian coal measure sequences. The emerging uplift provided a major sediment provenance area and represented a barrier behind which restricted anoxic conditions flourished, conditions favouring the preservation of organic matter. Late Permian and Triassic sequences are absent across the crestal portions of the uplift. However, the emerging, sea-ward facing flank of the uplift would have been subject to marginal and shallow marine, wave-base, barrier and strand bar deposition during the Lower Permian, conditions known in the onshore to favour better reservoir development.Gas demand to the greater Sydney region is anticipated to exceed supply by the year 2000, and new gas markets are being eagerly sought in time for the expiration, in 2006, of the current contract under which gas is supplied to Sydney via the Moomba pipeline.Cretaceous, Tasman Sea rift related, structuring is subordinate to that of the earlier compressional and wrench related structuring. Several new structural targets have been added to the existing inventory of prospects and leads, including some now considered optiminally located with respect to source rock and reservoir development.

Geological overview of the 2021 offshore acreage release areas

2021 ◽  
Vol 61 (2) ◽  
pp. 294
Author(s):  
Thomas Bernecker ◽  
Ryan Owens ◽  
Andrew Kelman ◽  
Kamal Khider
Keyword(s):  
Development Strategy ◽  
Information Management System ◽  
Petroleum Exploration ◽  
Upper Permian ◽  
Data Repository ◽  
Release Process ◽  
Multidisciplinary Study ◽  
Eastern Australia ◽  
Northern Carnarvon Basin ◽  
Offshore Petroleum

In 2021, a total of 21 areas were released for offshore petroleum exploration. They are located in the Bonaparte Basin, Browse Basin, Northern Carnarvon Basin, Otway Basin, Sorell Basin and Gippsland Basin. Despite COVID-19 negatively impacting the industry, participation in the acreage release nomination process was again robust. However, as has been the case in recent years, industry interest is focussed on those areas that are close to existing discoveries and related infrastructure. In tune with the Australian government’s resource development strategy, the areas being offered for exploration are likely to supply extra volumes of natural gas, both for export to Southeast Asian markets and domestically to meet the forecasted shortage in supply to eastern Australia. According to the 2019 implementation of a modified release process, only one period for work program bidding has been scheduled. The closing date for all submissions is Thursday, 3 March 2022. Geoscience Australia continues to support industry activities by acquiring, interpreting and integrating pre-competitive datasets that are made freely available in the context of the agency’s regional petroleum geological studies. As part of a multidisciplinary study, new data, including regional seismic and petroleum systems modelling, for the Otway Basin are now available. Also, a stratigraphic/sedimentological review of the upper Permian to Early Triassic succession in the southern Bonaparte Basin has been completed, the results of which are being presented at this APPEA conference. Large seismic and well data sets, submitted under the Offshore Petroleum and Greenhouse Gas Storage Act 2006 (OPGSSA), are made available through the National Offshore Petroleum Information Management System (NOPIMS). Additional data and petroleum-related information can be accessed through Geoscience Australia’s data repository.

Stratigraphic evolution of the Paleozoic Stikine assemblage in the Stikine and Iskut rivers area, northwestern British Columbia

1991 ◽  
Vol 28 (6) ◽  
pp. 958-972 ◽  
Author(s):  
Derek A. Brown ◽  
James M. Logan ◽  
Michael H. Gunning ◽  
Michael J. Orchard ◽  
Wayne E. Bamber
Keyword(s):  
Middle Devonian ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Upper Permian ◽  
Lower Permian ◽  
Early Permian ◽  
Lower Carboniferous ◽  
Modern Analogue ◽  
Arc Setting ◽  
Coralline Limestone

The Stikine assemblage, the "basement" of Stikinia, extends 500 km along the western flank of the Intermontane Belt, east of younger Coast Belt plutons. Four different stratigraphic successions are characteristic of Lower to Middle Devonian, Carboniferous and Permian rocks in the Stikine and Iskut rivers area. West of Forrest Kerr Creek are penetratively deformed Lower to Middle Devonian island-arc volcaniclastic rocks, coralline limestone, and felsic tuff. Fringing carbonate buildups in an arc setting are best illustrated in the sequence at Round Lake where Lower Carboniferous mafic-dominated, bimodal submarine volcanic rocks grade upward into two distinctive coarse echinoderm limestone units and medial siliceous siltstone and limestone conglomerate. Conodont colour alteration indices for Lower Carboniferous rocks near Newmont Lake indicate an anomalously low-temperature thermal history. Upper Carboniferous–Permian polymictic volcanic conglomerate and Lower Permian limestone overlie these strata there. The Scud River sequence is distinguished by subgreenschist- to greenschist-grade Carboniferous(?) volcanic and sedimentary rocks overlain by a structurally thickened package (greater than 1000 m) of Lower Permian limestone. Local calcalkaline pyroclastic rocks interfinger with limestone near the top of the Scud River sequence. Basinal, shelf, and shallow-water carbonate facies developed in the Early Permian, giving way to calcalkaline volcanism in Late Permian followed by deposition of deep-water chert and argillite.The tectonic setting during the Devonian and Carboniferous is comparable with modern Pacific volcanic arcs and atolls, but there is no modern analogue for the shelf-carbonate accumulation during the Early Permian which characterizes the Stikine assemblage and permits Cordilleran-scale correlations. Permian fusulinid and coral species have very close affinity to those of the McCloud Limestone of the eastern Klamath Mountains, California. Other geologic events common to both Stikinia and the Eastern Klamath terrane are Devonian limestone breccia deposition, Lower Permian limestone accumulation with McCloud faunal affinity, Carboniferous and Permian calcalkaline volcanism, and Upper Permian tuffaceous limestone. Stratigraphic differences include the absence of quartz detritus in Devonian strata and lack of thick Upper Permian volcanic rocks in the Stikine River area.

Late Palaeozoic biogeography of East Asia and palaeontological constraints on plate tectonic reconstructions

1988 ◽  
Vol 326 (1589) ◽  
pp. 189-227 ◽  
Keyword(s):  
East Asia ◽  
Upper Permian ◽  
Lower Permian ◽  
The Tibetan Plateau ◽  
Plate Tectonic ◽  
Early Permian ◽  
Equatorial Latitude ◽  
Southern Boundary ◽  
Late Palaeozoic ◽  
Rugose Coral

Biogeographical patterns of late Palaeozoic rugose coral genera are analysed for the Lower Carboniferous (Visean), early Lower Permian (Asselian/Sakmarian), late Lower Permian (Qixian) and early Upper Permian (Maokoan) of East Asia. Boundaries to the biotic regions are defined to coincide with tectonically significant suture zones to test rival hypotheses about the plate tectonic reconstruction of that region. Three numerical techniques are employed to cluster areas on the basis of shared endemic taxa; parsimony analysis of endemism, principal coordinates analysis and single linkage cluster analysis. Geographical variation in overall diversity is also considered. These results are compared with empirically derived patterns based on other groups of organisms. Major conclusions from this work are as follows, (i) During the Carboniferous and early Permian, the Cathaysian region (North and South China Blocks, Tarim Terrane, Kunlun Terrane, Qiangtang Terrane) formed one cohesive biotic region lying tropically or subtropically; it did not start to fragment until the Upper Permian, (ii) This region was biotically isolated from Central Asia at least during the Carboniferous and Lower Permian, (iii) The southern boundary to the Cathaysian region does not coincide with a single suture zone through time, nor is it sharply defined. Instead there appears to be a gradual faunal impoverishment southwards across the Tibetan Plateau. This implies that faunal ranges are controlled only by the prevailing global climatic regime and not by a geographical barrier, (iv) The Lhasa and Himalaya Terranes shared a similar fauna until the mid-Permian, when a marked faunal disjunction developed coincident with the Zangbo Suture, (v) For terrestrial floras, the barrier to biotic exchange between the North China Block and Angaraland started to break down in the late Permian. It follows that no major oceanic break (‘Palaeotethys’) can be recognized within the Cathaysian region during the late Palaeozoic on palaeontological evidence. This region then formed an integral part of the Gondwanaland craton, extending up into broadly tropical latitudes, and did not become separated from it until the late Lower Permian. The Tienshan-Yinshan Suture is the most likely site of ‘Palaeotethys’, which appears to have occupied a broadly equatorial latitude. Combined with evidence on the ages of the various Asian sutures, this raises significant problems for those who demand a large ocean in their Carboniferous to early Permian palaeogeographical reconstructions of this region.

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