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Detrital U–Pb zircon and 40Ar/39Ar muscovite geochronology of Triassic and Jurassic strata in the southern East Kunlun, northern Tibet Plateau and their geological implications
Geological Journal ( IF 1.4 ) Pub Date : 2022-08-25 , DOI: 10.1002/gj.4569
Bo Zhou 1 , Yunpeng Dong 1, 2 , Zhao Yang 1 , Johann Genser 3 , Franz Neubauer 3 , Dengfeng He 1 , Bo Hui 1 , Xiaohui Shi 1
Affiliation  

Geochronological dating of detrital minerals from sedimentary rocks can provide invaluable records of the erosional and unroofing history of orogenic systems and link specific sources with their sinks in sedimentary basins. Aiming to establish a better understanding of the thermal and erosional evolution of the East Kunlun Orogenic Belt (E-KOB), northern Tibet Plateau during the Mesozoic, integrated detrital U–Pb zircon, and 40Ar/39Ar muscovite dating was applied to Triassic and Jurassic strata in the southern E-KOB in this study. Detrital U–Pb zircon ages of clastic rocks from Triassic and Jurassic formations show major age populations at 2,600–2,200 Ma, 2,000–1,700 Ma, 1,000–600 Ma, 530–340 Ma, and 320–220 Ma, while the 40Ar/39Ar dating of detrital muscovite yield dominantly Devonian ages with uniform early-middle Devonian peak ages (380–405 Ma). Our new detrital U–Pb zircon and 40Ar/39Ar muscovite ages, combined with the previous palaeocurrent data and comparison with published U–Pb zircon, and 40Ar/39Ar muscovite ages of potential source areas, suggest that the E-KOB was the major source for Triassic and Jurassic strata in the southern East Kunlun. Devonian detrital muscovite 40Ar/39Ar ages of the Triassic and Lower Jurassic strata are consistent with the age of syn- and post-collisional magmatic activity in E-KOB related with the post-collisional thermal relaxation after closure of the Qimantagh back-arc basin. The Lower Triassic sedimentary deposits were associated with the subduction of the Kunlun Ocean, which is part of the Palaeo-Tethys Ocean. The E-KOB-derived material in Upper Triassic and Lower Jurassic formations implies that significant surface uplift, unroofing and erosion occurred during the Late Triassic and continued into the Early Jurassic in the East Kunlun region.

中文翻译:

青藏高原北部东昆仑南部三叠系和侏罗系碎屑U-Pb锆石和40Ar/39Ar白云母年代学及其地质意义

对沉积岩中的碎屑矿物进行地质年代测定可以提供造山系统侵蚀和剥落历史的宝贵记录,并将特定来源与其在沉积盆地中的汇联系起来。为了更好地了解东昆仑造山带 (E-KOB)、青藏高原北部中生代的热力和侵蚀演化,将碎屑 U-Pb 锆石和40 Ar/ 39 Ar 白云母测年应用于三叠纪和本研究中 E-KOB 南部的侏罗系地层。三叠纪和侏罗纪碎屑岩的碎屑 U-Pb 锆石年龄显示主要年龄分布在 2,600–2,200 Ma、2,000–1,700 Ma、1,000–600 Ma、530–340 Ma 和 320–220 Ma,而40 Ar/ 39碎屑白云母产量的 Ar 年代测定主要是泥盆纪年龄,具有一致的早中期泥盆纪峰值年龄(380-405 Ma)。我们新的碎屑 U-Pb 锆石和40 Ar/ 39 Ar 白云母年龄,结合之前的古电流数据以及与已发表的 U-Pb 锆石和潜在源区的40 Ar/ 39 Ar 白云母年龄的比较,表明 E-KOB是东昆仑南部三叠系和侏罗系地层的主要来源。泥盆纪碎屑白云母40 Ar/ 39三叠统和下侏罗统地层的年龄与E-KOB的同碰撞和碰撞后岩浆活动的年龄一致,这与Qimantagh弧后盆地关闭后的碰撞后热松弛有关。下三叠统沉积物与昆仑洋的俯冲有关,昆仑洋是古特提斯洋的一部分。上三叠统和下侏罗统地层中的 E-KOB 衍生物质表明,东昆仑地区晚三叠世发生了明显的地表抬升、剥落和侵蚀,并持续到早侏罗世。
更新日期:2022-08-25
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