scholarly journals New biostratigraphic evidence of Late Permian to Late Triassic deposits from Central Tibet and their paleogeographic implications

Lithosphere ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 683-696 ◽  
Author(s):  
Gui-chun Wu ◽  
Zhan-sheng Ji ◽  
Wei-hua Liao ◽  
Jian-xin Yao
Keyword(s):  
Middle Triassic ◽  
Carbonate Platform ◽  
Lower Triassic ◽  
Upper Triassic ◽  
Suture Zone ◽  
Late Triassic ◽  
Upper Permian ◽  
Early Triassic ◽  
Late Permian ◽  
The North

Abstract Triassic deposits in the Bangong-Nujiang Suture Zone are important for understanding its tectonic nature and evolutionary history, but have not been systematically studied due to a lack of biostratigraphic data. For a long time, the Upper Triassic Quehala Group featuring clasolite has been regarded as the only rocky unit. In recent years, the silicite-dominated Gajia Formation that bears radiolarian fossils was suggested to represent Ladinian to Carnian deposits. The Upper Permian and Lower Triassic rocks have never been excavated and thus are considered to be absent. This research, however, reveals that fossils aged from the Late Permian to Anisian of the Middle Triassic and Norian of the Late Triassic have been preserved in the central Bangong-Nujiang Suture Zone, which provides evidence of Upper Permian to early Middle Triassic deposits and provides new insights on the Upper Triassic strata as well. A new Triassic strata succession is thus proposed for the Bangong-Nujiang Suture Zone, and it demonstrates great similarities with those from Lhasa to the south and Qiangtang to the north. Therefore, we deduce that the Bangong-Nujiang Suture Zone was under a similar depositional setting as its two adjacent terranes, and it was likely a carbonate platform background because limestones were predominant across the Triassic. The newly acquired biostratigraphic data indicate that Lhasa and Qiangtang could not have been located on two separate continents with disparate sedimentary settings; therefore, the Bangong-Nujiang Suture Zone likely did not represent a large ocean between them. This conclusion is supported by lithostratigraphic and paleomagnetic research, which revealed that Lhasa and Qiangtang were positioned at low to middle latitudes during the Early Triassic. Combining this conclusion with fossil evidence, we suggest that the three main Tibetan terranes were in the same palaeobiogeographic division with South China, at least during the Latest Permian to Early Triassic. The Early Triassic conodont species Pachycladina obliqua is probably a fossil sign of middle to low latitudes in palaeogeography.

THE GEOLOGICAL EVOLUTION OF THE SOUTHERN TAROOM TROUGH AND THE OVERLYING SURAT BASIN

1974 ◽  
Vol 14 (1) ◽  
pp. 50 ◽  
Author(s):  
N. F. Exon
Keyword(s):  
Late Jurassic ◽  
Lower Triassic ◽  
Stream Sediments ◽  
Lower Jurassic ◽  
Late Triassic ◽  
Upper Permian ◽  
Lower Permian ◽  
Early Triassic ◽  
The South ◽  
The North

Isopach, structure contour, and palaeo-geological maps illustrate the geological development of the southern Taroom Trough and the lower part of the Surat Basin sequence.The meridional southern Taroom Trough, 50,000 km2 in area, is a southerly subsurface extension of the outcropping Bowen Basin. It is fault-bounded to the east and plunges northward. The maximum thickness of sedimentary fill increases northward from less than 400 m to 10,000 m, and consists of Lower Permian marine sediments, Upper Permian coal measures, Lower Triassic redbeds, and Middle Triassic stream sediments. The trough's present western margin is depositional, but the faulted eastern margin started to form in the Late Permian in the south and in the Early Triassic in the north; movement ceased in the Early Triassic in the south and in the Late Triassic in the north. Tectonic movements did not recur until Late Jurassic time.Late Triassic erosion preceded deposition of Surat Basin sediments. These sediments extended over ever wider areas, even the basal sands spreading far beyond the Taroom Trough. The fully-developed Surat Basin is 300,000 km2 in area, and contains up to 2500 m of dominantly continental Jurassic sediments and dominantly marine Lower Cretaceous sediments. Lower Jurassic stream sediments (the main petroleum producers of the basin) are thickest and coarsest above the Taroom Trough, suggesting steady subsidence and compaction of the trough sediments.By the Late Jurassic this compaction had virtually ceased, and epeirogenic uplift had given the basin its present shape, with the Mimosa Syncline (above the Taroom Trough) and the south-westerly-trending Dirranbandi Syncline (above a basement depression) being major structural features.Petroleum, which is probably derived from both Permian and Jurassic sources, is most abundant in the Lower Jurassic sandstone on either side of the Mimosa Syncline. Some aspects of the migration and trapping of Permian petroleum are discussed, and it is suggested that the Lower Jurassic Hutton Sandstone in the virtually unexplored Bollon area could be prospective.

scholarly journals Comparative size evolution of marine clades from the Late Permian through Middle Triassic

Paleobiology ◽  
2015 ◽  
Vol 42 (1) ◽  
pp. 127-142 ◽  
Author(s):  
Ellen K. Schaal ◽  
Matthew E. Clapham ◽  
Brianna L. Rego ◽  
Steve C. Wang ◽  
Jonathan L. Payne
Keyword(s):  
Body Size ◽  
Middle Triassic ◽  
Size Reduction ◽  
Late Triassic ◽  
Early Triassic ◽  
Large Species ◽  
Late Permian ◽  
Triassic Boundary ◽  
Median Size ◽  
Permian Extinction

AbstractThe small size of Early Triassic marine organisms has important implications for the ecological and environmental pressures operating during and after the end-Permian mass extinction. However, this “Lilliput Effect” has only been documented quantitatively in a few invertebrate clades. Moreover, the discovery of Early Triassic gastropod specimens larger than any previously known has called the extent and duration of the Early Triassic size reduction into question. Here, we document and compare Permian-Triassic body size trends globally in eight marine clades (gastropods, bivalves, calcitic and phosphatic brachiopods, ammonoids, ostracods, conodonts, and foraminiferans). Our database contains maximum size measurements for 11,224 specimens and 2,743 species spanning the Late Permian through the Middle to Late Triassic. The Permian/Triassic boundary (PTB) shows more size reduction among species than any other interval. For most higher taxa, maximum and median size among species decreased dramatically from the latest Permian (Changhsingian) to the earliest Triassic (Induan), and then increased during Olenekian (late Early Triassic) and Anisian (early Middle Triassic) time. During the Induan, the only higher taxon much larger than its long-term mean size was the ammonoids; they increased significantly in median size across the PTB, a response perhaps related to their comparatively rapid diversity recovery after the end-Permian extinction. The loss of large species in multiple clades across the PTB resulted from both selective extinction of larger species and evolution of surviving lineages toward smaller sizes. The within-lineage component of size decrease suggests that only part of the size decrease can be related to the end-Permian kill mechanism; in addition, Early Triassic environmental conditions or ecological pressures must have continued to favor small body size as well. After the end-Permian extinction, size decrease occurred across ecologically and physiologically disparate clades, but this size reduction was limited to the first part of the Early Triassic (Induan). Nektonic habitat or physiological buffering capacity may explain the contrast of Early Triassic size increase and diversification in ammonoids versus size reduction and slow recovery in benthic clades.

scholarly journals The Upper Triassic deposits of the west Bangong-Nujiang suture zone and their paleogeographic implications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guichun Wu ◽  
Zhansheng Ji ◽  
Gary G. Lash ◽  
Jianxin Yao
Keyword(s):  
Central Region ◽  
Upper Triassic ◽  
Suture Zone ◽  
Late Triassic ◽  
Upper Permian ◽  
The West ◽  
Apparent Lack ◽  
Sedimentary Succession ◽  
Depositional Setting ◽  
Qiangtang Terrane

AbstractThe Bangong-Nujiang Suture Zone (BNSZ) of Tibet (Xizang) has been interpreted to represent a relic of the Bangong-Nujiang Ocean. However, the existence of this ocean during Triassic time remains a point of contention. A sedimentary succession spanning the Upper Permian through Triassic described from the central BNSZ suggests that the Lhasa and South Qiangtang terranes were contiguous thus negating the existence of a terrane-separating ocean during Triassic time. However, the apparent lack of Triassic deposits in the west BNSZ has called into question the existence of Triassic deposits in the central region of the BNSZ. Our biostratigraphic work in the Wuga Formation of the Gaize area has yielded abundant Norian conodonts thus confirming the existence of Upper Triassic deposits in the west BNSZ. The clastic deposits of the Wuga Formation are herein interpreted to be of Rhaetian age. Moreover, intercalated limestone and chert are termed the Dongnale Formation of Norian age. The Norian to Rhaetian succession can be correlated with strata of the central BNSZ as well as with deposits of the Lhasa Terrane and the South Qiangtang Terrane. Similar stratigraphies among these regions through the Late Triassic suggests a shared depositional setting and that the BNSZ was not an ocean in Norian and Rhaetian time.

scholarly journals Geochemistry and Zircon U-Pb-Hf Isotopes of Metamorphic Rocks from the Kaiyuan and Hulan Tectonic Mélanges, NE China: Implications for the Tectonic Evolution of the Paleo-Asian and Mudanjiang Oceans

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 836
Author(s):  
Zuozhen Han ◽  
Jingjing Li ◽  
Zhigang Song ◽  
Guyao Liu ◽  
Wenjian Zhong ◽  
...  
Keyword(s):  
Tectonic Evolution ◽  
Middle Triassic ◽  
Late Triassic ◽  
Metamorphic Rocks ◽  
Late Permian ◽  
Early Permian ◽  
Ne China ◽  
The North ◽  
Tectonic Mélange ◽  
Final Closure

The Late Paleozoic–Early Mesozoic tectonic evolution of the Changchun-Yanji suture (CYS) was mainly associated with the Paleo-Asian and Mudanjiang tectonic regimes. However, the spatial and temporal overprinting and variations of these two regimes remains are still dispute. In order to evaluate this issue, in this contribution, we present new zircon U-Pb ages and a whole-rock geochemical and zircon Hf isotopic dataset on a suite of metamorphic rocks, including gneisses, actinolite schist, leptynites, and biotite schists, from tectonic mélanges in northern Liaoning and central Jilin provinces, NE China. Based on zircon LA-ICP-MS U-Pb dating results, protoliths show wide ranges of aging spectrum, including Paleoproterozoic (2441 Ma), Early Permian (281 Ma), Late Permian (254 Ma), and Late Triassic (230 Ma). The Permian protoliths of leptynites from the Hulan Tectonic Mélange (HLTM) and gneisses from the Kaiyuan Tectonic Mélange (KYTM) exhibit arc-related geochemical signatures, implying that the Paleo-Asian Ocean (PAO) did not close prior to the Late Permian. The Late Triassic protoliths of gneisses from the KYTM, in combination with previously reported coeval igneous rocks along the CYS, comprises a typical bimodal igneous suite in an E–W-trending belt, suggesting a post-orogenic extensional environment. Consequently, we infer that the final closure of the PAO took place during the Early–Middle Triassic. The Early Permian protoliths of biotite schists from the HLTM are alkali basaltic rocks and contain multiple older inherited zircons, which, in conjunction with the geochemical features of the rocks, indicate that they were generated in a continental rift related to the initial opening of the Mudanjiang Ocean (MO). Data from this contribution and previous studies lead us to conclude that the MO probably opened during the Middle Triassic, due to the north–south trending compression caused by the final closure of the PAO.

Fishes from the Lower Triassic portion of the Sulphur Mountain Formation in Alberta, Canada: geological context and taxonomic composition

2015 ◽  
Vol 52 (8) ◽  
pp. 557-568 ◽  
Author(s):  
Andrew G. Neuman
Keyword(s):  
Environmental Factors ◽  
Middle Triassic ◽  
Lower Triassic ◽  
Taxonomic Composition ◽  
Marine Fishes ◽  
Early Triassic ◽  
Western Margin ◽  
East Greenland ◽  
The North ◽  
North American Craton

The Sulphur Mountain Formation in Alberta, Canada, comprises shales, siltstones, and limestones laid down on the continental shelf and shoreline along the western margin of the North American Craton during the Early and Middle Triassic. At least 13 taxa of fossil marine fishes have been found at a number of Triassic localities along the Front Ranges and foothills in Alberta. Common taxa (Boreosomus, Birgeria, Bobasatrania, Australosomus, Saurichthys, parasemionotids, and coelacanths) found at localities in Alberta are similar to those found at the classic Lower and Middle Triassic localities near Wapiti Lake, British Columbia, and in East Greenland, Spitzbergen, Madagascar, and China. The occurrence of Lower Triassic fishes in western Alberta shows that this fauna was widespread, occurring over at least 1000 km of shoreline, and that ecological and environmental factors were similar along the western edge of the Panthalassic Ocean during the Early Triassic.

scholarly journals Hydrocarbon Potential of the Late Permian and the Late Triassic Source Rocks from the Qamdo (Changdu) Basin, Eastern Tibet and Its Linkage with the Sea Level Change

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhaolin Qi ◽  
Yalin Li ◽  
Chengshan Wang
Keyword(s):  
Organic Matter ◽  
Source Rock ◽  
Upper Triassic ◽  
Source Rocks ◽  
Late Triassic ◽  
Upper Permian ◽  
Late Permian ◽  
Petroleum Potential ◽  
Eastern Tibet ◽  
Rock Eval

The Qamdo Basin in eastern Tibet has significant petroleum potential and previous studies indicate that the basin contains thick potential source rocks of the Late Permian and the Late Triassic ages. In this paper, the petroleum potential of samples from measured the Upper Permian and Upper Triassic outcrop sections was evaluated on the basis of sedimentological, organic petrographic and geochemical analyses. Initial evaluations of total organic carbon contents indicated that shale samples from the Upper Permian Tuoba Formation and the Upper Triassic Adula and Duogala Formations have major source rock potential, while carbonate rocks from the Upper Triassic Bolila Formation are comparatively lean in organic matter More detailed analyses of OM-rich shale samples from the Tuoba, Adula and Duogala Formations included Rock-eval, elemental analyses, gas chromatography and organic petrography. Maceral compositions and plots of atomic O/C versus H/C indicate that the organic matter present in the samples is primarily Type II with a mixed source. Analyses of acyclic isoprenoid biomarkers indicate the organic matter was deposited under reducing and sub-to anoxic conditions. Based on the high vitrinite reflectance (Ro>1.3%) and Rock-eval data, the samples are classified as highly to over-mature, suggesting that the Tuoba, Adula and Duogaila Formation shales may generate thermogenic gas. Source rock intervals in the three formations are interpreted to have been deposited in marginal-marine environment during transgressions and under a warm and moist climatic condition.

Late Permian to Middle Triassic radiolarian faunas from northern Thailand

2000 ◽  
Vol 74 (5) ◽  
pp. 789-811 ◽  
Author(s):  
Katsuo Sashida ◽  
Hisayoshi Igo ◽  
Shuko Adachi ◽  
Katsumi Ueno ◽  
Yoshimichi Kajiwara ◽  
...  
Keyword(s):  
Middle Triassic ◽  
Early Triassic ◽  
Late Permian ◽  
Chiang Mai ◽  
Important Data ◽  
Triassic Boundary ◽  
Northern Thailand ◽  
The North ◽  
Permian Triassic Boundary ◽  
Almost Continuous

Moderately well-preserved Late Permian to Middle Triassic radiolarians are identified in chert beds that occur in the Shan-Thai Block of northern Thailand. These radiolarians are identical to the faunas of the Late Permian Neoalbaillella ornithoformis and N. optima Assemblage Zones and the Triassic Parentactinia nakatsugawaensis and Triassocampe coronata Assemblage Zones reported in chert sequences of Japan. We discovered the radiolarian faunas, apparently indicating Late Permian and Early Triassic ages, in almost continuous sequences of chert and shale exposed in the north of Chiang Mai. The occurrence of these radiolarian faunas provides important data to solve the P/T (Permian/Triassic) boundary in pelagic sequences. Our present discovery also furnishes significant data to reconstruct the paleobiogeography of Mainland Thailand during Late Permian to Middle Triassic times. Fifty species belonging to 35 genera, including three unidentified genera, are investigated taxonomically. Four new species Pseudospongoprunum? chiangdaoensis, Cenosphaera igoi, Cenosphaera? rugosa, and Tlecerina? apsornae are described.

scholarly journals Stratabound copper-lead-zinc mineralisation in the Permo-Triassic of central East Greenland

1982 ◽  
Vol 143 ◽  
pp. 1-42
Author(s):  
B Thomassen ◽  
L.B Clemmensen ◽  
H.K Schønwandt
Keyword(s):  
Middle Triassic ◽  
Lower Triassic ◽  
Upper Triassic ◽  
Alluvial Fan ◽  
Upper Permian ◽  
Geochemical Data ◽  
East Greenland ◽  
Lead Zinc ◽  
Copper Lead ◽  
Carbonate Buildup

Stratabound and stratiform copper-lead-zinc-mineralised horizons confined to specific sedimentary fades in the Permo-Triassic Jameson Land Basin of East Greenland were revealed during recent exploration and sedimentological studies. The occurrences are divided into fault-bounded-stratabound and stratabound-stratiform mineralisation. The first group comprises lead-zinc-copper mineralisation in Upper Permian limestone; the remaining mineralisation falls in the second group which is subdivided into mineralisation hosted in mudstones, in sandstones with mudflasers and in sandstones and conglomerates. A lithogeochemical programme helped to define the mineralised horizons in the Triassic. During the interpretation of the geochemical data an empiric statistical function was introduced which is an estimate of how anomalous the 95 per cent fractile is for individual elements compared with the frequency distribution around the median. The Upper Permian sediments host copper in basal shoreline conglomerates, zinc-lead-copper in lagoonal mudstones and lead-zinc-copper in carbonate buildup and shelf fades. The Lower Triassic contains copper-lead mineralisation in alluvial fan sediments, the Middle Triassic hosts lead-zinc-copper in sandy shoreline limestones and lagoonal mudstones and copper-lead-zinc in gypsiferous lacustrine sandstones and mudstones while the Upper Triassic contains copper in both dolomitic lacustrine sandstones and mudstones and in overlying carbonate-rich fluvial channel sandstones.

Early and Middle Triassic trends in diversity, evenness, and size of foraminifers on a carbonate platform in south China: implications for tempo and mode of biotic recovery from the end-Permian mass extinction

Paleobiology ◽  
2011 ◽  
Vol 37 (3) ◽  
pp. 409-425 ◽  
Author(s):  
Jonathan L. Payne ◽  
Mindi Summers ◽  
Brianna L. Rego ◽  
Demir Altiner ◽  
Jiayong Wei ◽  
...  
Keyword(s):  
South China ◽  
Mass Extinction ◽  
Evolutionary Dynamics ◽  
Middle Triassic ◽  
Carbonate Platform ◽  
Early Triassic ◽  
Data Set ◽  
Recovery Pattern ◽  
Biotic Recovery ◽  
Permian Mass Extinction

Delayed biotic recovery from the end-Permian mass extinction has long been interpreted to result from environmental inhibition. Recently, evidence of more rapid recovery has begun to emerge, suggesting the role of environmental inhibition was previously overestimated. However, there have been few high-resolution taxonomic and ecological studies spanning the full Early and Middle Triassic recovery interval, leaving the precise pattern of recovery and underlying mechanisms poorly constrained. In this study, we document Early and Middle Triassic trends in taxonomic diversity, assemblage evenness, and size distribution of benthic foraminifers on an exceptionally exposed carbonate platform in south China. We observe gradual increases in all metrics through Early Triassic and earliest Middle Triassic time, with stable values reached early in the Anisian. There is little support in our data set for a substantial Early Triassic lag interval during the recovery of foraminifers or for a stepwise recovery pattern. The recovery pattern of foraminifers on the GBG corresponds well with available global data for this taxon and appears to parallel that of many benthic invertebrate clades. Early Triassic diversity increase in foraminifers was more gradual than in ammonoids and conodonts. However, foraminifers continued to increase in diversity, size, and evenness into Middle Triassic time, whereas diversity of ammonoids and conodonts declined. These contrasts suggest decoupling of recovery between benthic and pelagic environments; it is unclear whether these discrepancies reflect inherent contrasts in their evolutionary dynamics or the differential impact of Early Triassic ocean anoxia or associated environmental parameters on benthic ecosystems.

scholarly journals New insights on the early Mesozoic evolution of multiple tectonic regimes in the northeastern North China Craton from the detrital zircon provenance of sedimentary strata

Solid Earth ◽  
2018 ◽  
Vol 9 (6) ◽  
pp. 1375-1397 ◽  
Author(s):  
Yi Ni Wang ◽  
Wen Liang Xu ◽  
Feng Wang ◽  
Xiao Bo Li
Keyword(s):  
North China Craton ◽  
North China ◽  
Early Jurassic ◽  
Orogenic Belt ◽  
Detrital Zircons ◽  
Late Triassic ◽  
Early Triassic ◽  
The South ◽  
The North ◽  
Early Mesozoic

Abstract. To investigate the timing of deposition and provenance of early Mesozoic strata in the northeastern North China Craton (NCC) and to understand the early Mesozoic paleotectonic evolution of the region, we combine stratigraphy, U–Pb zircon geochronology, and Hf isotopic analyses. Early Mesozoic strata include the Early Triassic Heisonggou, Late Triassic Changbai and Xiaoyingzi, and Early Jurassic Yihe formations. Detrital zircons in the Heisonggou Formation yield  ∼ 58 % Neoarchean to Paleoproterozoic ages and  ∼ 42 % Phanerozoic ages and were sourced from areas to the south and north of the basins within the NCC, respectively. This indicates that Early Triassic deposition was controlled primarily by the southward subduction of the Paleo-Asian oceanic plate beneath the NCC and collision between the NCC and the Yangtze Craton (YC). Approximately 88 % of the sediments within the Late Triassic Xiaoyingzi Formation were sourced from the NCC to the south, with the remaining  ∼ 12 % from the Xing'an–Mongolia Orogenic Belt (XMOB) to the north. This implies that Late Triassic deposition was related to the final closure of the Paleo-Asian Ocean during the Middle Triassic and the rapid exhumation of the Su–Lu Orogenic Belt between the NCC and YC. In contrast,  ∼ 88 % of sediments within the Early Jurassic Yihe Formation were sourced from the XMOB to the north, with the remaining  ∼ 12 % from the NCC to the south. We therefore infer that rapid uplift of the XMOB and the onset of the subduction of the Paleo-Pacific Plate beneath Eurasia occurred in the Early Jurassic.

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