Sandstone provenance analysis in Longyan supports the existence of a Late Paleozoic continental arc in South China
Sandstone provenance analysis in Longyan supports the existence of a Late Paleozoic continental arc in South China
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DOI：
10.1016/j.tecto.2020.228400
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发表时间：
2020-04
期刊：
影响因子：
2.9
通讯作者：
Chao Li;Xiumian Hu;Jian‐Gang Wang;P. Vermeesch;E. Garzanti
中科院分区：
文献类型：
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作者：
Chao Li;Xiumian Hu;Jian‐Gang Wang;P. Vermeesch;E. Garzanti
由于岩浆和变质作用的记录有限，中国南部晚古生代的构造背景仍然存在争议。本文介绍了龙岩上古生界富含石英(73%~90%)，贫岩屑(2%~12%)和长石(3%~25%)的砂岩的沉积学资料和物源分析。泥盆系砂岩主要含有变质岩屑(如石英岩)，而石炭-二叠系砂岩主要含有长英质火山岩和次火山岩屑，表明它们来自长英质火山岩。泥盆系-石炭系砂岩的碎屑锆石U-Pb年龄谱在~440 Ma和420~380 Ma之间显示模式，具有中元古代的从属年龄成分，表明南岭地体和武夷地体的中西部是最有可能的最终沉积源。二叠系砂岩继承了上述时代成分，但也包括约290 Ma和1850 Ma的峰值。~290M a组分对应于中国东南部和日本西南部晚古生代岩浆活动的时代。在中国南部和日本西南部出露的二叠纪-三叠纪地层中也发现了大量碎屑锆石，年龄在350-250 Ma之间。根据区域资料，结合碎屑锆石的年龄和Hf同位素特征，推测中国东南部沿海地区存在晚古生代陆弧，并为邻近的沉积盆地提供碎屑。该地区局部出露的二叠纪-三叠纪火成岩可能代表了该大陆弧的残余。弧长可能是上古生界碳酸盐岩台地向西撤退的原因。
Because of the limited magmatic and metamorphic record, the Late Paleozoic tectonic setting in South China remains controversial. This paper presents sedimentologic data and provenance analysis of Upper Paleozoic sandstones in Longyan, which are rich in quartz (73–90%) and poor in lithic fragments (2–12%) and feldspar (3–25%). Devonian sandstones contain mostly metamorphic lithic fragments (e.g., quartzite), whereas Carboniferous-Permian sandstones contain mostly felsic volcanic and subvolcanic lithic fragments indicating provenance from felsic volcanic rocks. Detrital zircon U-Pb age spectra of Devonian-Carboniferous sandstones display modes at ~440 Ma and 420–380 Ma, with subordinate Mesoproterozoic age components, pointing at the Nanling terrane and the western-middle part of the Wuyi terrane as most likely ultimate sediment sources. Permian sandstones inherited the age components mentioned above, but also include peaks at ~290 Ma and ~1850 Ma. The ~290 Ma component corresponds to the age of Late Paleozoic magmatism in southeastern China and southwest Japan. Numerous detrital zircons aged at 350–250 Ma also occur in Permo-Triassic strata exposed across South China and southwest Japan. Based on regional data and on the ages and Hf isotope signatures of detrital zircon, we infer that a Late Paleozoic continental arc existed in the coastal area of southeastern China and contributed detritus to the adjacent sedimentary basins. The Permo-Triassic igneous rocks locally exposed in the area may represent the remnant of that continental arc. Arc growth may have been responsible for the westward retreat of a broad Upper Paleozoic carbonate platform.