Late Paleozoic peperites in West Junggar, China, and how they constrain regional tectonic and palaeoenvironmental setting
Late Paleozoic peperites in West Junggar, China, and how they constrain regional tectonic and palaeoenvironmental setting
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DOI：
10.1016/j.gr.2012.04.012
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发表时间：
2013-03
影响因子：
6.1
通讯作者：
Shi Chen;Zhaojie Guo;G. Pe‐Piper;Bei Zhu
中科院分区：
文献类型：
--
作者：
Shi Chen;Zhaojie Guo;G. Pe‐Piper;Bei Zhu
在西准噶尔地区的太勒古拉组底部首次发现晚古生代钙长石。这一发现对恢复准噶尔地区晚古生代的演化具有重要意义。钙霞石形成厚度达500 m的系列，与玄武熔岩和沉积岩互层。四种类型的perperites被描述和解释为导致玄武熔岩推到潮湿，松散的沉积物在其基底接触。对一个被熔岩包裹的凝灰岩透镜进行的锆石LA-ICP-MS U-Pb定年表明，该凝灰岩形成于晚泥盆世（约1000年）。364Ma）。含泥质岩单元可能形成于水深小于3 km的环境中，一般未变形，与蛇绿岩的高度变形切片形成对比，它们出现在Darbut和白碱滩蛇绿岩带两侧100 km范围内的连续地层剖面中。它们表明，达尔布特和白碱滩蛇绿岩带不应被解释为重要的板块边界，而是代表了在一个连续的浅残留洋盆内沿沿着构造线性构造隆起的下伏洋壳。这些钙榴岩形成于残留洋盆的扩张阶段，代表了洋壳形成的最后阶段。
Late Paleozoic peperites have been identified for the first time at the bottom of Tailegula Formation in West Junggar, China. This finding is significant for the reconstruction of Late Paleozoic evolution in the Junggar region. The peperites form successions up to 500m thick interbedded with basaltic lava and sedimentary rocks. Four types of peperites are described and interpreted as resulting from basaltic lava bulldozed into wet, unconsolidated sediments at their basal contacts. Zircon LA-ICP-MS U–Pb dating of a tuff lens enclosed by lava showed that the peperites formed in the Late Devonian (ca. 364Ma). The peperite-bearing units probably formed at a water depth of less than 3km and are generally undeformed, occurring in continuous stratigraphic sections distributed regionally over a distance of 100km on either side of the Darbut and Baijiantan ophiolitic belts, in contrast to the highly deformed slices of ophiolite. They demonstrate that the Darbut and Baijiantan ophiolitic belts should not be interpreted as significant plate boundaries and represent the underlying ocean crust uplifted along tectonic lineaments within a continuous shallow remnant ocean basin. The peperites formed during the spreading phase of the remnant ocean basin and represent the final stages of creation of oceanic crust.