I-type granitoids associated with the early Paleozoic intracontinental orogenic collapse along pre-existing block boundary in South China
I-type granitoids associated with the early Paleozoic intracontinental orogenic collapse along pre-existing block boundary in South China
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与华南早古生代陆内造山崩塌相关的I型花岗岩
DOI：
10.1016/j.lithos.2016.02.002
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发表时间：
2016-04
期刊：
影响因子：
3.5
通讯作者：
Li, Jie
中科院分区：
文献类型：
--
作者：
Yu, Yang;Huang, Xiao-Long;He, Peng-Li;Li, Jie
早古生代武夷—云开造山运动导致华夏和华南扬子地块东部发生广泛的岩浆活动。确定相关岩浆作用的性质对于理解造山运动至关重要，而造山运动的构造背景和地球动力学驱动力仍然是个谜。江西省张家坊岩体（438±3Ma）主要由花岗闪长岩组成，并伴有丰富的同期镁铁质-中微粒包体（MME）（~433±5Ma）。花岗闪长岩样品呈弱过铝质（A/CNK = 1.05–1.09），SiO2 含量较低（61.9–64.9 wt.%），Fe2O3（4.6–5.6 wt.%）、MgO（2.2–2.8 wt.%）和 CaO（4.3–4.8 wt.%）含量较高，由于富含矿物成分，属于 I 型岩组。岩石中的角闪石。它们表现出强负的全岩εNd(t)值(−11至−9)和锆石εHf(t)值(−14至−4)，与华夏地块的基底相似，但与扬子地块东部半山铺和红霞桥岩体同时存在的I型花岗岩不同，其Sr、Ba、Th和U的含量要低得多。MME样品显示出明显的负Nb-Ta-Ti异常和总体上，全岩εNd(t)(−9～−7)和锆石εHf(t)负值(−9～−4)小于寄主花岗闪长岩，最好解释为幔源熔体与壳源岩浆混合不充分的产物。扬子东部和华夏地块的边界应穿过张家坊岩体附近的西部地区(即凭祥市)。靠近地块边界的早古生代I型花岗岩的εNd(t)和εHf(t)值均为负值，说明两个地块整体上存在武夷—云开造山运动之前的古老基底，更倾向于陆内造山模式。然而，江山-绍兴-凭祥断裂带沿线经常出现早古生代基性岩和具有同时期金属微环境的I型花岗岩，说明造山塌陷期间地幔衍生熔体对邻近地块边界的古代基底进行了广泛的改造。在陆内造山崩塌期间，预先存在的块体边界可能促进了软流圈上升和玄武岩底侵。
The early Paleozoic Wuyi–Yunkai orogeny resulted in extensive magmatism in the Cathaysia and eastern Yangtze blocks, South China. Identifying the nature of related magmatism is essential for understanding the orogeny that remains enigmatic with regard to its tectonic setting and geodynamic driving force. The Zhangjiafang pluton (438 ± 3 Ma) in western Jiangxi province is composed of predominant granodiorite with abundant coeval mafic-intermediate microgranular enclaves (MMEs) (~ 433 ± 5 Ma). The granodiorite samples are weakly peraluminous (A/CNK = 1.05–1.09) and have low SiO2(61.9–64.9 wt.%) and high Fe2O3(4.6–5.6 wt.%), MgO (2.2–2.8 wt.%) and CaO (4.3–4.8 wt.%), belonging to I-type suite due to abundant amphibole in the rocks. They exhibit strongly negative whole-rock εNd(t) values (− 11 to − 9) and zircon εHf(t) values (− 14 to − 4), similar to the basement of the Cathaysia Block, but distinguishable from simultaneous I-type granites of the Banshanpu and Hongxiaqiao plutons in eastern Yangtze Block in much lower Sr, Ba, Th and U. The MME samples show pronounced negative Nb–Ta–Ti anomalies and have overall less negative whole-rock εNd(t) (− 9 to − 7) and zircon εHf(t) values (− 9 to − 4) than the host granodiorite, which are best interpreted as products of mantle-derived melts that mixed insufficiently with crust-derived magma.The block boundary between the eastern Yangtze and Cathaysia blocks should pass through the nearby west area (i.e., Pingxiang City) of the Zhangjiafang pluton. The Early Paleozoic I-type granitic rocks near the block boundary have all negative εNd(t) and εHf(t) values, demonstrating an overall ancient basement of the two blocks prior to the Wuyi–Yunkai orogeny, preferring an intracontinental orogeny model. However, the early Paleozoic mafic rocks and I-type granites with coeval MMEs were frequently present along the Jiangshan–Shaoxing–Pingxiang Fault zone, illustrating widespread modification of the ancient basement adjacent to the block boundary by mantle-derived melt during the orogenic collapse. The pre-existing block boundary might have promoted asthenosphere upwelling and basaltic underplating during the intracontinental orogenic collapse.
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DOI：
--
发表时间：
2002
期刊：
--
影响因子：
--
作者：
W. Gang
通讯作者：
W. Gang
影响因子：
3.5
作者：
Feifei Zhang;Yuejun Wang;Aimei Zhang;W. Fan;Yuzhi Zhang;Jian-Wei Zi
通讯作者：
Feifei Zhang;Yuejun Wang;Aimei Zhang;W. Fan;Yuzhi Zhang;Jian-Wei Zi
影响因子：
6.1
作者：
Yuejun Wang;W. Fan;Guowei Zhang;Yanhua Zhang
通讯作者：
Yuejun Wang;W. Fan;Guowei Zhang;Yanhua Zhang
影响因子：
5.8
作者：
R. Larson
通讯作者：
R. Larson
DOI：
--
发表时间：
2009
期刊：
Geology in China
影响因子：
--
作者：
Pang Ying-chun
通讯作者：
Pang Ying-chun