Multi-stage crustal melting from Late Permian back-arc extension through Middle Triassic continental collision to Late Triassic post-collisional extension in the East Kunlun Orogen

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.

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Late Permian–early Middle Triassic back-arc basin development in West Qinling, China

Journal of Asian Earth Sciences ◽

10.1016/j.jseaes.2014.02.021 ◽

2014 ◽

Vol 87 ◽

pp. 116-129 ◽

Cited By ~ 31

Author(s):

Lin Li ◽

Qingren Meng ◽

Alex Pullen ◽

Carmala N. Garzione ◽

Guoli Wu ◽

...

Keyword(s):

Middle Triassic ◽

Late Permian ◽

West Qinling ◽

Basin Development ◽

Back Arc ◽

Early Middle Triassic

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LA-ICP-MS zircon U–Pb and sericite 40Ar/39Ar ages of the Songjianghe gold deposit in southeastern Jilin Province, Northeast China, and their geological significance

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2018-0254 ◽

2019 ◽

Vol 56 (6) ◽

pp. 607-628

Author(s):

Xiao-Tian Zhang ◽

Jing-Gui Sun ◽

Zheng-Tao Yu ◽

Quan-Heng Song

Keyword(s):

Gold Deposit ◽

Gold Deposits ◽

Pacific Plate ◽

Jilin Province ◽

Late Triassic ◽

Retrograde Metamorphism ◽

Late Permian ◽

Multi Stage ◽

Metallogenic Epoch ◽

Host Rocks

The Songjianghe deposit is a newly discovered altered gold deposit in the southeastern Jiapigou-Haigou Gold Metallogenic Belt (JHGMB) in southeastern Jilin Province of NE China. The host rocks were considered to be the Mesoproterozoic Seluohe Group, and the metallogenic epoch lacked accurate isotopic constraints. To determine the age and metallogenic setting of the deposit, we describe the geologic characteristics of the deposit and present the results of petrographic and geochronologic analyses of the host rocks and ores. The ore bodies are hosted within a suite of amphibolite facies metamorphic rocks superimposed by greenschist facies indicative of retrograde metamorphism. Zircon U–Pb dating results indicate that the host rocks belong to the Jiapigou Group that formed at the end of the Neoarchean (2543–2527 Ma). Subsequently, the rocks successively underwent metamorphism during the late Neoarchean (2521–2506 Ma), retrograde metamorphism caused by the closure of the Paleo-Asian Ocean during the late Permian to Early Triassic (262–250 Ma), and extension after the closure of the Paleo-Asian Ocean during the Late Triassic (231–210 Ma). Sericite 40Ar/39Ar dating results suggest that the Songjianghe deposit formed during the Late Jurassic between 157 Ma and 156 Ma. By combining these new insights with those of previous studies, we propose that the Songjianghe deposit is a mesothermal gold deposit and that mineralization occurred during the extensional period in the intermittent stage that followed the first subduction of the Paleo-Pacific Plate. All the gold deposits in the JHGMB formed from the late Permian to Early Cretaceous by multi-stage mineralization events that corresponded temporally with the tectonic evolution of the Paleo-Asian Ocean and the episodic subduction of the Paleo-Pacific Plate.

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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 ◽

10.3390/min10090836 ◽

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.

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Late Permian back-arc extension of the eastern Paleo-Tethys Ocean: Evidence from the East Kunlun Orogen, Northern Tibetan Plateau

Lithos ◽

10.1016/j.lithos.2019.05.006 ◽

2019 ◽

Vol 340-341 ◽

pp. 34-48 ◽

Cited By ~ 6

Author(s):

Xu Zhao ◽

Lebing Fu ◽

Junhao Wei ◽

Leon Bagas ◽

M. Santosh ◽

...

Keyword(s):

Tibetan Plateau ◽

Late Permian ◽

Northern Tibetan Plateau ◽

East Kunlun ◽

Tethys Ocean ◽

Back Arc

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Whole-rock geochemical variations and evolution of the arc-derived Murihiku Terrane, New Zealand

Geological Magazine ◽

10.1017/s0016756802006945 ◽

2002 ◽

Vol 139 (6) ◽

pp. 665-685 ◽

Cited By ~ 51

Author(s):

B. P. ROSER ◽

D. S. COOMBS ◽

R. J. KORSCH ◽

J. D. CAMPBELL

Keyword(s):

New Zealand ◽

Continental Crust ◽

Basaltic Andesite ◽

Middle Triassic ◽

Late Triassic ◽

Late Permian ◽

Rock Composition ◽

Upper Continental Crust ◽

Geochemical Parameters ◽

Early Middle Triassic

Arc-flank volcaniclastic sedimentation in the Murihiku Terrane of New Zealand lasted about 120 million years from Late Permian to Early Cretaceous time. Despite the effects of pervasive zeolite-facies alteration, whole-rock geochemical parameters for sandstones, siltstones and tuffs record changes in source-rock composition, both in time and along the length of the depositional basin. Sandstones are considered to give a more reliable indication of the state of evolution of the source volcanic arc than do the siltstones. The siltstones commonly contain detrital white mica flakes that are generally lacking in the sandstones, and are possibly of distal continental origin. Some also contain very fine felsic ash particles. Average abundances and normalized multi-element diagrams are used to estimate proportions of three model end-member source constituents, average upper-continental crust (UCC), high-K rhyolite (RHY) and basaltic andesite (AND). Sandstone provenance for the Southland Syncline sector changed from a predominantly basaltic-andesite source in Late Permian to early Middle Triassic time, for example, UCC:RHY:AND = 0:17:83 in the Early to early Middle Triassic, to highly felsic in the Middle to Late Triassic, reaching UCC:RHY:AND = 2:74:24 in the Late Triassic Oretian Stage. A UCC component became increasing significant from latest Triassic upward and the proportion of mafic to felsic volcanism increased again, with UCC:RHY:AND = 15:30:35 in the Middle Jurassic Temaikan Stage. Mix modelling suggests that along-arc source proportions varied, with greater mafic and upper continental crust contributions in the northern Kawhia segment than in the Southland segment. These patterns may be explained by deposition at an oceanic Aleutian-type arc margin, with transition to a continental oceanic arc character induced either by arc evolution and dissection, forearc sliver translation, or underplating of rafted microcontinental fragments.

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

Lithosphere ◽

10.1130/l1046.1 ◽

2019 ◽

Vol 11 (5) ◽

pp. 683-696 ◽

Cited By ~ 1

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.

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