西伯利亚克拉通Udachnaya金伯利岩筒麻粒岩捕虏体的变质P-T轨迹与构造意义  

Metamorphic P-T path of the granulite xenoliths from the Udachnaya kimberlite pipe,Siberian Craton,and tectonic implications

作　　者：武可馨 仝来喜 IONOV Dmitri Alepa 刘兆 李超[1] 韩新月 WU KeXin;TONG LaiXi;IONOV Dmitri Alepa;LIU Zhao;LI Chaoand HAN XinYue(State Key Laboratory of Continental Evolution and Early Life,Department of Geology,Northwest University,Xi'an 710069,China;Geosciences Montpellier,University of Montpellier,Montpellier 34095,France)

机构地区：[1]大陆演化与早期生命全国重点实验室,西北大学地质学系,西安710069 [2]蒙贝利埃地学中心,蒙贝利埃大学,蒙贝利埃34095

出　　处：《岩石学报》2025年第4期1297-1317,共21页Acta Petrologica Sinica

基　　金：国家自然科学基金重大项目(41890831);法国INSU-CNRS项目联合资助.

摘　　要：西伯利亚克拉通是全球著名的稳定克拉通之一,其下地壳的变质演化历史对于理解大陆动力学至关重要。关于该克拉通下地壳在古元古代时期的改造与重建,一直存在垂向构造和横向构造增生机制的争议。本研究聚焦于西伯利亚克拉通Udachnaya金伯利岩筒中的古元古代麻粒岩捕虏体,通过岩相学观察、矿物化学分析、多种地质温压计和P-T视剖面图模拟等方法,限定了其不同变质阶段的温压条件。研究识别出麻粒岩保留的3个不同的变质阶段:(1)早期进变质阶段(M1),以石榴子石、单斜辉石、斜长石、金红石和石英包裹体为代表,温压条件为740~770℃和1.04~1.12GPa;(2)峰期变质阶段(M2),矿物组合为基质石榴子石、单斜辉石、角闪石、金红石、斜长石和熔体,变斑晶石榴子石中可见针状金红石出溶,温压条件为900~912℃和1.37~1.39GPa;(3)退变质阶段(M3),以石榴子石和单斜辉石边部发育的角闪石+石英后成合晶为特征,温压条件为832~850℃和0.9~0.95GPa。上述温压条件和相图模拟结果表明该麻粒岩经历了峰期高压-超高温变质作用,并具有一条峰期前升温升压、峰期后近等温降压(ITD)特征的顺时针P-T轨迹,记录了陆-陆碰撞引发的地壳加厚和碰撞后的快速折返过程。结合前人的年代学结果,表明古元古代西伯利亚克拉通下地壳的改造和重建可能与同时期Columbia超大陆聚合(1.9~1.8Ga)有关。这一结果为理解西伯利亚克拉通的构造演化历史和板块构造作用的启动时间具有启示意义。The Siberian Craton is one of the most renowned stable cratons in the world,and its lower crustal metamorphic evolution history is crucial for understanding continental dynamics.There has been an ongoing academic debate regarding the tectonic mechanisms responsible for the modification and reconstruction of the lower crust during the Paleoproterozoic,including vertical and horizontal tectonic accretion.This study focuses on the Paleoproterozoic granulite xenoliths from the Udachnaya kimberlite pipe in the Siberian Craton.Through petrographic observations,mineral chemistry analysis,various geological thermobarometers and P-T pseudosection modeling,we have constrained the P-T conditions of different metamorphic stages recorded in the granulites.In this study,three distinct metamorphic stages of the granulites are identified as:(1)the early prograde stage(M1),characterized by the mineral assemblage of garnet,clinopyroxene,plagioclase,rutile,and quartz inclusions,with P-T conditions of 740~770℃and 1.04~1.12GPa;(2)the peak metamorphic stage(M2),with the assemblage of matrix garnet,clinopyroxene,amphibole,plagioclase,rutile,and melt,with exsolved acicular rutiles in garnet porphyroblasts,with P-T conditions of 900~912℃and 1.37~1.39GPa;and(3)the retrograde stage(M3),characterized by the symplectite of amphibole+quartz developed at the rims of garnet and clinopyroxene,with P-T conditions of 832~850℃and 0.9~0.95GPa.The above P-T conditions and phase equilibrium modeling results indicate that they experienced a peak high-pressure and ultrahigh-temperature metamorphism,with a clockwise P-T path of prograde heating and pressure-up followed by post-peak isothermal decompression(ITD),recording the crust thickening caused by continent-continent collision and subsequent rapid exhumation processes.Combined with the previous chronological results of others,it suggests that the transformation and reconstruction of the lower crust of the Siberian Craton in the Paleoproterozoic may be related to the contemporaneous assembly of

关 键 词：西伯利亚克拉通 Udachnaya金伯利岩筒 麻粒岩捕虏体 变质P-T轨迹 构造意义 

分 类 号：P588.347[天文地球—岩石学]