南阿尔金—柴北缘高压-超高压变质带研究进展、问题及挑战

南阿尔金—柴北缘高压-超高压变质带研究进展、问题及挑战

张建新1，孟繁聪1，C. G. Mattinson2

1. 中国地质科学院地质研究所, 北京 100037;2. Department of Geological & Environmental Sciences, Stanford University, Stanford CA 94305-2115 U S A.

收稿日期:2007-09-20 修回日期:2007-09-20 出版日期:2007-09-20 发布日期:2007-09-20

Progress, Controversies and Challenge of Studies on South Altyn Tagh-North Qaidam HP/UHP Metamorphic Belt

ZHANG Jian-xin1, MENG Fan-cong1, Mattinson C G2

1. Institute of Geology, CAGS, Beijing 100037, China;2. Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305-2115, U S A

Received:2007-09-20 Revised:2007-09-20 Online:2007-09-20 Published:2007-09-20

摘要/Abstract

摘要： 南阿尔金—柴北缘高压-超高压（HP/UHP）变质带为近10年来所新厘定，它分布在青藏高原北缘，延伸近1 000 km，被阿尔金断裂分成南阿尔金和柴北缘两部分，以含少量榴辉岩、石榴橄榄岩和含柯石英的片麻岩为特征。根据野外地质观察、岩石组合分析及其岩石学特征，可把南阿尔金—柴北缘HP/UHP变质带划分为6个HP/UHP变质单元，从西向东分别是：江尕勒萨依榴辉岩-片麻岩单元（JSU）；巴什瓦克石榴橄榄岩-高压麻粒岩单元（BWU）；鱼卡—落凤坡榴辉岩-片麻岩（片岩）单元（YLU）；绿粱山石榴橄榄岩-高压麻粒岩单元（LLU）；锡铁山榴辉岩-片麻岩单元（XTU）；都兰榴辉岩-片麻岩单元（DLU）。研究显示，6个HP/UHP变质单元在岩石组合、形成的温度压力条件及变质演化历史等方面存在明显差异；榴辉岩相变质时代变化在420～500 Ma之间，可能反映了早古生代沿南阿尔金—柴北缘HP/UHP变质带的多阶段或穿时性的俯冲作用。

Abstract: The South Altyn Tagh (SAT)-North Qaidam (NQD) HP/UHP metamorphic belt extends approximately 1000 km along the northern margin of the Tibetan Plateau，and is truncated by the Altyn Tagh sinistral strikeslip fault and splitted into two parts: the South Altyn Tagh region and the North Qaidam region. Based on rock associations, petrologic criteria and the field relationships, six HP/UHP metamorphic units can be distinguished in the South Altyn Tagh（SAT）-North Qaidam (NQD) region (Fig. 1A). From west to east, they are: the Jianggalesayi eclogite-gneiss unit (JSU), the Bashiwake garnet peridotite-high pressure granulite unit (BWU), the Yuka eclogitegneiss (schist) unit (YLU), the Luliangshan garnet peridotite-gneiss unit (LLU), the Xitieshan eclogite-gneiss unit (XTU) and the Dulan eclogite-gneiss unit (DLU). The geological relationship, petrology and geochronology indicate that these six HP/UHP metamorphic units have different rock associations, and underwent different p -T conditions and metamorphic histories. Geochronologyical dating for these eclogite-facies metamorphics yields ages between 500 and 420 Ma. This implies that a possible multiple or disachronous subduction took place along the SAT-NQD HP/UHP metamorphic belt.

张建新，孟繁聪，C. G. Mattinson. 南阿尔金—柴北缘高压-超高压变质带研究进展、问题及挑战[J]. J4.

ZHANG Jian-xin1, MENG Fan-cong1, Mattinson C G2. Progress, Controversies and Challenge of Studies on South Altyn Tagh-North Qaidam HP/UHP Metamorphic Belt[J]. J4.