Permian to early Triassic tectono-sedimentary evolution of the Mahu sag, Junggar Basin, western China: sedimentological implications of the transition from rifting to tectonic inversion

Tang, Wenbin; Zhang, Yuanyuan; Pe‐Piper, Georgia; Piper, David J. W.; Guo, Zhaojie; Li, Wei

doi:10.1016/j.marpetgeo.2020.104730

Cited by 51 publications

(14 citation statements)

References 36 publications

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“…Frequent SSDS in the medial part of rift basin lacustrine fill have been reported elsewhere. In the Permian Mahu Sag of Junggar Basin, north-western China, the Fengcheng Formation has much more abundant SSDS than either the underlying or overlying lacustrine units (Tang et al, 2020). Crustal thinning and mechanical subsidence in the Junggar Basin lasted about 20 Ma before the onset of a more regional thermal subsidence, and similar chronology is known from other rift basins (Tang et al, 2021c).…”

Section: Soft-sediment Deformation Structures and Tectonic Evolution ...mentioning

confidence: 65%

“…2). The Horton Group thus shows classic rift‐basin evolution with mechanical extension and subsidence reaching a maximum in the middle of the Group, similar to other rift basins in the world (Lambiase & Katz, 1990; Muravchik et al ., 2020; Tang et al ., 2021a,b). The Windsor Group represents the onset of regional thermal subsidence that continued into the Permian (Gibling & Rygel, 2008), interrupted by significant strike–slip deformation coinciding with the Mississippian–Pennsylvanian boundary (Piper & Pe‐Piper, 2021).…”

Section: Geological Setting and Stratigraphymentioning

confidence: 99%

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Architecture of lacustrine deposits in response to early Carboniferous rifting and Gondwanan glaciation, Nova Scotia, south‐east Canada

Tang,

Pe‐Piper,

Piper

et al. 2023

Sedimentology

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Upper Palaeozoic lacustrine basin deposits not only record local tectonism but are also an archive to evaluate global palaeoclimate changes linked to the Late Palaeozoic Gondwanan ice age. The Tournaisian Horton Group of Nova Scotia, south‐east Canada, accumulated in rift basins following the final accretion of peri‐Gondwanan terranes to the Appalachians. Sedimentology, mineralogy and geochemistry of the well‐exposed sandstones and shales at the classic Blue Beach section (ca 353.5 to 352 Ma) reveal the interplay of local tectonism and global climatic controls on lacustrine sedimentation. The lacustrine depositional environment gradually transitioned from deep water offshore at the base of the section to wave‐dominated and fluvial‐dominated nearshore at the top. Multiple small transgressive‐regressive sedimentation cycles have an average 21 ka duration, likely related to Milankovitch cyclicity. Unusually abundant soft‐sediment deformation structures (SSDS) and landslides are the sedimentary responses to frequent earthquakes during the most active phase of rift subsidence. The overall succession shows changes from a shallowing‐up balanced‐filled to an overfilled lacustrine basin. The chemical weathering intensity index and the Th/K ratio show a longer‐term trend from dry and cool conditions low in the section to humid and warm conditions near the top, with rapid change in the transition period. The section records the peak of the global mid‐Tournaisian carbon isotope excursion and the corresponding cooling event (354 Ma to approximately 351 Ma). The sedimentary succession is a response to long‐ and short‐term climatic cycles influencing lake level and sediment supply during the time of maximum rift basin subsidence recorded by the soft‐sediment deformation structures.

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Section: Soft-sediment Deformation Structures and Tectonic Evolution ...mentioning

confidence: 65%

Section: Geological Setting and Stratigraphymentioning

confidence: 99%

Architecture of lacustrine deposits in response to early Carboniferous rifting and Gondwanan glaciation, Nova Scotia, south‐east Canada

Tang,

Pe‐Piper,

Piper

et al. 2023

Sedimentology

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“…The Mahu Sag has undergone investigations that suggest an Early Permian syn-rift to middle Permian post-rift stage and a Late Permianearly Triassic tectonic inversion stage (Liang et al, 2020;Tang et al, 2021b), following the Devonian-Carboniferous infilling of a remnant ocean (Chen et al, 2014).…”

Section: Geological Settingmentioning

confidence: 99%

“…The Mahu Sag developed along a major NE–SW trending tectonic depression during the post‐orogenic extensional relaxation stage, between the fault‐bounded West Junggar and Luliang Uplift (Zhang et al, 2018). The Mahu Sag has undergone investigations that suggest an Early Permian syn‐rift to middle Permian post‐rift stage and a Late Permian‐early Triassic tectonic inversion stage (Liang et al, 2020; Tang et al, 2021b), following the Devonian‐Carboniferous infilling of a remnant ocean (Chen et al, 2014).…”

Section: Geological Settingmentioning

confidence: 99%

Subaqueous felsic volcanic sequence and its contribution to the ancient alkaline lacustrine deposits in the Mahu Sag, Junggar Basin, NW China

Zhang

et al. 2023

Geological Journal

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Subaqueous eruptions alter the chemical conditions of the lake by intensifying the interaction between hot volcanic rocks and water, resulting in the exchange of alkalis. The lower part of the Fengcheng Formation in the Mahu Sag, NW China, has abundant rhyolitic welded tuff and related pyroclastic deposits, which were deposited under ancient alkaline lacustrine deposits of the Fengcheng Formation. Despite this, the effect of the eruption process on the formation of the alkali lake remains unclear. To gain a better understanding of the eruptive behaviour and emplacement processes, detailed drilling core descriptions, microscopic observations, and interpretations of textural characteristics of rhyolitic welded tuff units and adjacent volcano‐sedimentary associations have been conducted. The rhyolitic welded tuff can be categorized into seven lithofacies units based on the degree of welding, devitrification characteristics, pore development, and filling characteristics. The age of eruption was determined through zircon U–Pb dating of the rhyolitic welded tuff, revealing it to be approximately 300 Ma, thereby providing constraints on the deposition time of alkaline lacustrine deposits. Mudstones that encase the welded tuff unit and quenched structures such as perlitic fractures, quench cracks of spherulite and lithophysae, and chalcedony spherules indicate that the welded tuff unit was formed through subaqueous eruption. Alkali fractionation (sodium and potassium) occurs in the spherulite and lithophysae zone and at the top condensation boundary, demonstrating that the subaqueous eruption process significantly enhanced devitrification and hydration, causing sodium to escape from the welded tuff and released into the lake water as sodium ions. The rhyolitic welded tuff provides evidence of the evolution of a subaqueous felsic eruption where the water‐rock reaction played a fundamental role in alkalizing the lake by providing the lake with sodium ions in Mahu Sag.

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“…The Junggar Basin, Xinjiang Uygur Autonomous Region, northwestern China, covers an area of about 134000 km 2 , and continental Mesozoic sedimentary rock sequences are welldeveloped (Tang et al 2021). Our study site is located in the southern Junggar Basin, which is part of the Kazakhstan-Junggar plate (Figure 1).…”

Section: Geological Settingmentioning

confidence: 99%

A Late Triassic vegetation record from the Huangshanjie Formation, Junggar Basin, China: possible evidence for the Carnian Pluvial Episode

Peng

Slater

Vajda

2022

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The Carnian Pluvial Episode (CPE; ∼234‒232 million years ago) is characterized by an accelerated hydrological cycle, global warming and a period of elevated biotic turnover. Using spores and pollen, we reconstruct vegetation and climate changes through a Carnian‒Norian (Upper Triassic) interval of the Huangshanjie Formation from the Junggar Basin, China. Four palynofloras were identified, representing distinct vegetation communities. Among these palynofloras, we observed a prominent shift from a conifer-dominated climax forest community, with common ginkgophytes and bennettites, to a fern-dominated community, suggestive of an environmental perturbation. We interpret this change as a regional shift in vegetation, likely caused by increased humidity, consistent with the CPE. Our records represent the first indication of a possible CPE-induced vegetation response in the Junggar Basin and highlight how this event likely affected floral communities of inland Laurasia.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5738637

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Permian to early Triassic tectono-sedimentary evolution of the Mahu sag, Junggar Basin, western China: sedimentological implications of the transition from rifting to tectonic inversion

Cited by 51 publications

References 36 publications

Architecture of lacustrine deposits in response to early Carboniferous rifting and Gondwanan glaciation, Nova Scotia, south‐east Canada

Architecture of lacustrine deposits in response to early Carboniferous rifting and Gondwanan glaciation, Nova Scotia, south‐east Canada

Subaqueous felsic volcanic sequence and its contribution to the ancient alkaline lacustrine deposits in the Mahu Sag, Junggar Basin, NW China

A Late Triassic vegetation record from the Huangshanjie Formation, Junggar Basin, China: possible evidence for the Carnian Pluvial Episode

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