【24h】

Petrogenesis of granitoids and associated xenoliths in the early Paleozoic Baoxu and Enping plutons, South China: Implications for the evolution of the Wuyi-Yunkai intracontinental orogen

机译:华南地区早古生代包许和恩平岩体中花岗岩和相关异岩的成岩作用:对武夷—云开陆内造山带演化的启示

获取原文
获取原文并翻译 | 示例

摘要

The early Paleozoic Wuyi-Yunkai orogen was associated with extensive felsic magmatic activities and the orogenic core was mainly distributed in the Yunkai and Wugong domains located in the western Cathaysia block and in the Wuyi domain located in the central part of the Cathaysia block. In order to investigate the evolution of the Wuyi-Yunkai orogen, elemental and Sr-Nd isotopic analyses were performed for granites from the Baoxu pluton in the Yunkai domain and from the Enping pluton in the central part of the Cathaysia block. The Baoxu pluton consists of biotite granite with abundant xenoliths of gneissic granite, granodiorite and diorite, and the Enping pluton is mainly composed of massive granodiorite. Biotite granites (441 +/- 5 Ma) and gneissic granite xenolith (443 +/- 4 Ma) of the Baoxu pluton are all weakly peraluminous (A/CNK = 1.05-1.10). They show high Sr/Y and La/Yb ratios and have negative bulk-rock e(Nd)(t) values (-7.0 to -4.4), which are similar to coeval gneissic S-type granites in the Yunkai domain and were probably derived from dehydration melting of a sedimentary source with garnet residue in the source. Granodiorites (429 +/- 3 Ma) from Enping and granodiorite xenolith (442 +/- 4 Ma) from Baoxu are metaluminous and have REE patterns with enriched light REE and flat middle to heavy REE, possibly generated by the dehydration melting of an igneous basement at middle to lower crustal level. Diorite xenolith from Baoxu is ultrapotassic (K2O = 4.9 wt%), has high contents of MgO (7.0 wt%), Cr (379 ppm) and Ni (171 ppm) and shows pronounced negative Nb, Ta and Ti anomalies. This xenolith also has negative eNd(t) value (-3.6) and low Rb/Ba and high Ba/Sr ratios, and is thus interpreted to be derived from an enriched lithospheric mantle with the breakdown of phlogopite. Early Paleozoic I- and S-type granites in the Wuyi-Yunkai orogen mostly have negative e(Nd)(t) values and do not have juvenile components, consistent with genesis by an intracontinental orogenic event. These early Paleozoic granites occur near the ancient suture zone between the Yangtze and Cathaysia blocks and have high La/Yb and Sr/Y ratios, likely due to the existence of residual garnet in the source, suggesting the thickened crust at ca. 440 Ma. The 450-440 Ma gneissic S-type granites near the suture zone are earlier than those in the central part of the Cathaysia block (similar to 430 Ma). The crustal thickening along the ancient suture zone at 440 Ma propagated into the central part of the Cathaysia block as evidenced by the 430 Ma granites. Early Paleozoic I-type granites near the suture zone clearly show involvement of significant mantle-derived materials, in contrast to granites in the central part of the Cathaysia block. The ancient suture zone may have acted as channels for the emplacement of mafic magmas during the collapse of an intracontinental orogen.
机译:早古生代武夷-云开造山带与广泛的长英质岩浆活动有关,造山岩芯主要分布在华夏地块西部的云开和武功地区以及华夏地块中部的武夷地区。为了研究武夷—云开造山带的演化,对云开地区宝x岩体和华夏地块中部恩平岩体的花岗岩进行了元素和Sr-Nd同位素分析。包旭岩体由黑云母花岗岩,片麻岩花岗岩,花岗闪长岩和闪长岩的丰富的异岩组成,恩平岩体主要由块状花岗闪长岩组成。包旭岩体的黑云母花岗岩(441 +/- 5 Ma)和片麻岩花岗岩异岩(443 +/- 4 Ma)都是弱铝质的(A / CNK = 1.05-1.10)。它们显示出较高的Sr / Y和La / Yb比,并且具有负的块岩e(Nd)(t)值(-7.0至-4.4),类似于云开域的片麻片麻质S型花岗岩,并且可能来源于沉积物的脱水融化,其中有石榴石残留物。恩平的花岗闪长岩(429 +/- 3 Ma)和宝绪的花岗闪长石异岩(442 +/- 4 Ma)是金属质的,其稀土元素分布形式为轻质稀土元素和中重质稀土元素,可能是由于火成岩的脱水融化而产生的。地壳中低层。宝x的闪长石闪长岩是超钾的(K2O = 4.9 wt%),MgO(7.0 wt%),Cr(379 ppm)和Ni(171 ppm)的含量很高,并且显示出明显的负Nb,Ta和Ti异常。该异岩还具有负的eNd(t)值(-3.6),低的Rb / Ba和高的Ba / Sr比,因此被解释为源自金云母分解的富集岩石圈地幔。武夷云开造山带中的早古生代I型和S型花岗岩大多具有负e(Nd)(t)值,并且没有幼年成分,这与陆内造山事件的成因相一致。这些早期古生代花岗岩发生在扬子和华夏地块之间的古代缝合带附近,并且具有较高的La / Yb和Sr / Y比,这可能是由于源中残留了石榴石,这表明ca的地壳变厚了。 440毫安缝合带附近的450-440 Ma片麻岩S型花岗岩比华夏地块中部的花岗岩早(类似于430 Ma)。 430 Ma花岗岩表明,沿古老的缝合线带440 Ma的地壳增厚传播到了华夏地块的中部。与华夏地块中部的花岗岩相比,缝合线附近的早古生代I型花岗岩清楚地显示出大量地幔衍生的物质。在大陆内造山带塌陷期间,古老的缝合带可能已成为铁质岩浆沉积的通道。

著录项

  • 来源
    《Journal of Asian earth sciences》 |2018年第MAY1期|59-74|共16页
  • 作者单位

    Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Guangdong, Peoples R China;

    Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Guangdong, Peoples R China;

    Univ Hong Kong, Dept Earth Sci, Pokfulam Rd, Hong Kong, Hong Kong, Peoples R China;

    Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Guangdong, Peoples R China;

  • 收录信息
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Xenolith; Ancient suture zone; Intracontinental orogeny; Continental growth; South China;

    机译:异种岩;古代缝合带;陆内造山作用;陆续生长;华南;

相似文献

  • 外文文献
  • 中文文献
获取原文

联系方式:18141920177 (微信同号)

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号