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首页> 外文期刊>Journal of geodynamics >Orogeny processes of the western Jiangnan Orogen, South China:Insights from Neoproterozoic igneous rocks and a deep seismic profile
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Orogeny processes of the western Jiangnan Orogen, South China:Insights from Neoproterozoic igneous rocks and a deep seismic profile

机译：华南江南造山带的造山过程：新元古代火成岩的见解和深部地震剖面

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摘要

The Jiangnan Orogen is a collisional suture belt between the Yangtze and Cathaysia Blocks in South China, with many unanswered questions regarding its tectonic evolution. Using the basement structure of the Jiangnan Orogen, we investigate the granite and dacite exposed along the western Jiangnan Orogen and present new LA-ICP-MS zircon U-Pb ages, Hf isotopes, and whole rock geochemistry data. The results suggest that the granite plutons belong to the calc-alkaline series and are typical S-type granites. It yields a mean U-Pb age of 854 +/- 2 Ma, which is determined from the core of zircon and possibly inherited from its source or wall rocks. The initial emplacement age of granite may be 826-805 Ma, whereas the dacites yield an age of 805 +/- 1.6 Ma and belong to the shoshonite series. The initial Hf-isotope ratios (Hf-176/Hf-177) in the granite sample are mostly negative sHf(t), with a few of positive value with 1.38-1.6 Ga T-DM and 1.67-2.06 Ga T-DM2, whereas the dacite samples have mostly positive epsilon Hf(t), with a 0.78-1.6 Ga T-DM and 0.83-2.2 Ga T-DM2t. A comparison of the epsilon Hf(t) and T-DM2t with the corresponding intruded strata, helps illustrate the origin of the magma and the finals stages ofcollision. Based on our results, we conclude that the western Jiangnan Orogen was a back-arc foreland basin that developed on the margin of the Yangtze continent and collided with the Cathaysia Block, forming a continent-arc-continent accretionary orogeny between 860 and 800 Ma. (C) 2016 Elsevier Ltd. All rights reserved.
机译：江南造山带是中国南方扬子地带与华夏地块之间的碰撞缝合带，其构造演化存在许多悬而未决的问题。利用江南造山带的基底结构，我们调查了沿江南造山带西部暴露的花岗岩和榴辉岩，并提供了新的LA-ICP-MS锆石U-Pb年龄，Hf同位素和整个岩石地球化学数据。结果表明，花岗岩岩体属于钙碱性系列，是典型的S型花岗岩。它的平均U-Pb年龄为854 +/- 2 Ma，这是由锆石的核心确定的，并且可能是从其源岩或围岩继承而来的。花岗岩的初始沉积年龄可能为826-805 Ma，而dacites的初始沉积年龄为805 +/- 1.6 Ma，属于shoshonite系列。花岗岩样品中的初始Hf同位素比（Hf-176 / Hf-177）大多为负sHf（t），在1.38-1.6 Ga T-DM和1.67-2.06 Ga T-DM2下为正值，钠铁矿样品的εHf（t）大部分为正，具有0.78-1.6 Ga T-DM和0.83-2.2 Ga T-DM2t。将εHf（t）和T-DM2t与相应的侵入岩层进行比较，有助于说明岩浆的起源和碰撞的最后阶段。根据我们的结果，我们得出结论，江南造山带是一个后扬子前陆盆地，它在长江大陆的边缘发育并与华夏地块相撞，形成了860至800 Ma之间的大陆-弧-大陆增生造山运动。 （C）2016 Elsevier Ltd.保留所有权利。

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