Detrital record of late-stage silicic volcanism in the Emeishan large igneous province
Detrital record of late-stage silicic volcanism in the Emeishan large igneous province
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峨眉山火成岩省晚期硅质火山作用的碎屑记录
DOI：
10.1016/j.gr.2019.09.015
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发表时间：
2020-03
影响因子：
6.1
通讯作者：
He Ben
中科院分区：
文献类型：
--
作者：
Deng Xu-Sheng;Yang Jianghai;Cawood P.A.;Wang Xuan-Ce;Du Yuansheng;Huang Yan;Lu Shu-Fan;He Ben
硅质火山岩通常是追踪以镁铁质岩为主的大火成岩省（LIPs）岩浆演化的次要但关键的产物。然而，由于火山岩的晚期性质，它们由于大规模的喷发后侵蚀而具有较差的保存潜力。通过对峨眉山大碰撞造山带沉积岩物源的分析，追踪了峨眉山大碰撞造山带距今约260 Ma的侵蚀火山岩。右江盆地北方晚二叠世龙潭组砂岩中富含火山岩碎屑，泥岩中Al 2 O3/TiO 2比值较低。龙滩组碎屑锆石颗粒显示出典型的单峰U-Pb年龄谱，在约40 °处有一个显著峰。260毫安。这些碎屑锆石显示出类似于那些从板内/非造山岩浆结晶的整体地球化学亲和力。这些岩石学和地球化学特征与峨眉山火山岩的优势物源一致。在整个取样序列中，龙潭组下部~ 260 Ma的锆石普遍表现出较低的U/Yb（大部分< 0.5）和Th/Nb（大部分< 10）比值，以及较高的εHf（t）值（大部分在+3 ~+8之间）。在与龙潭组时间相当的近海单位--晒洼组中也观察到了类似的序列变化。这些一致的时间变化通过在右江盆地的沉积序列被解释为反映峨眉山LIP在晚二叠世的侵蚀去顶。结合前人对峨眉山陆面体中流纹岩和粗面岩的研究，揭示了晚火山作用以分离结晶作用为主，地壳同化作用减弱的成岩过程。
Silicic volcanic rocks generally constitute a minor, but key product to track the magmatic evolution in mafic rock dominated large igneous provinces (LIPs). However, for their generally late-stage nature of the silicic volcanic rocks they have a poor preservation potential due to extensive post-eruption erosion. We track the eroded volcanic rocks from the ∼260 Ma Emeishan LIP by analyzing the provenance of the LIP-derived sedimentary rocks. Sandstones from a cored succession of the Late Permian Longtan Formation in the northern Youjiang Basin are rich in volcanic rock fragments, and associated mudstones have low Al2O3/TiO2ratios. Detrital zircon grains from the Longtan Formation display typical unimodal U–Pb age spectra with a prominent peak at ca. 260 Ma. These detrital zircons show an overall geochemical affinity akin to those crystallized from within-plate/anorogenic magmas. Such petrological and geochemical characteristics are consistent with a dominant source from the Emeishan volcanic rocks. Through the sampled succession, zircon grains of ∼260 Ma from the lower Longtan Formation generally display lower U/Yb (most < 0.5) and Th/Nb (most < 10) ratios and higher εHf(t) values (mostly in the range of +3 to +8) than those from the upper part. A similar sequential variation has also been observed in the Shaiwa Formation, which is an offshore time-equivalent unit to the Longtan Formation. These consistent temporal variations through the sedimentary successions in the Youjiang Basin are interpreted to reflect erosional unroofing of the Emeishan LIP during the Late Permian. These results, integrated with previous studies on the rhyolites and trachytes in Emeishan LIP, reveal a fractional crystallization dominated petrogenetic process with diminishing crustal assimilation for the late-stage silicic volcanism.
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DOI：
10.5382/sp.17
发表时间：
2012
期刊：
--
影响因子：
--
作者：
J. W. Hedenquist;Michael Harris;F. Camus
通讯作者：
J. W. Hedenquist;Michael Harris;F. Camus
影响因子：
1.8
作者：
Qingyan Tang;Chusi Li;Mingjie Zhang;Yao Lin
通讯作者：
Qingyan Tang;Chusi Li;Mingjie Zhang;Yao Lin
影响因子：
3.5
作者：
Lilu Cheng;Yu Wang;J. S. Herrin;Zhong‐Yuan Ren;Zongfeng Yang
通讯作者：
Lilu Cheng;Yu Wang;J. S. Herrin;Zhong‐Yuan Ren;Zongfeng Yang
影响因子：
3.5
作者：
Hu Huang;Peter A. Cawood;Mingcai Hou;S. Ni;Jianghai Yang;Yuansheng Du;Huaguo Wen
通讯作者：
Hu Huang;Peter A. Cawood;Mingcai Hou;S. Ni;Jianghai Yang;Yuansheng Du;Huaguo Wen
影响因子：
3.9
作者：
Dai, Shifeng;Wang, Xibo;Zou, Jianhua
通讯作者：
Zou, Jianhua