摘要：
The composite Dunhuang orogenic belt (DOB),located on the east of Tarim Craton,is a vital link between the Tarim Craton and the North China Craton.In recent years,advanced progresses have been made in geological research of Dunhuang,Northwest China.Based on the available data,this contribution reviewed study history and advances of basic geological research in the DOB,summarized spatial-temporal distribution of Precambrian geological units and Precambrian tectono-thermal events,preliminarily discussed formation and evolution of Precambrian continental crust,as well as the affinity and tectonic evolution of Precambrian crystalline basement,and then proposed that:(1) The Precambrian crystalline basement in the DOB formed during ca.3.1 ～ 1.6Ga,with the main tectono-thermal events being subdivided into three stages of Neoarchean (ca.2.7 ～ 2.6Ga and 2.6 ～ 2.5Ga),Late Paleoproterozoic (ca.2.0 ～ 1.8Ga) and Early Mesoproterozoic (1.8 ～ 1.6Ga);(2) The Early Neoarchean (ca.2.7 ～2.6Ga) and Late Neoarchean (2.6 ～2.5Ga) are two major periods of crustal growth;whereas,the Late Paleoproterozoic (ca.2.0 ～ 1.8Ga) and Early Mesoproterozoic (1.8 ～ 1.6Ga) are main periods of crustal reworking,accompanied by certain degree of crustal growth;(3) The Precambrian crystalline basement within the DOB might initially amalgamated at the end of Neoarchean (～2.5Ga),and then underwent Late Paleoproterozoic (ca.2.0 ～ 1.8Ga) orogenic process.Until Early Mesoproterozoic (1.8 ～ 1.6Ga),the orogenic process terminated,forming the consolidated Precambrian crystalline basement;(4) Since the final formation of the Precambrian crystalline basement (after ～ 1.6Ga),the Dunhuang area was probably in a shutdown period lasted for nearly 1.2 billion years,without any tectono-thermal documents and sedimentary records of this period has been found so far (similar to a shield).Until the beginning of Silurian (～440Ma),the crystalline basement was involved into the accretionary orogenic processes related to the closure of the southern margin of Paleo-Asian Ocean,being reactivated and strongly reworked.%敦煌复合造山带位于塔里木克拉通东端,是连接塔里木克拉通和华北克拉通的重要纽带.近年来,敦煌基础地质研究取得了重大进展.本文简要回顾了敦煌基础地质研究历史和现状,系统归纳了区内前寒武纪地质单元时空分布特征及前寒武纪构造-热事件序列,初步讨论了前寒武纪大陆地壳形成和演化规律、前寒武纪结晶基底亲缘性及构造演化过程,提出:(1)敦煌造山带前寒武纪结晶基底形成于ca.3.1～1.6Ga,构造-热事件主要划分为新太古代(ca.2.7～2.6Ga和2.6～2.5Ga)、古元古代晚期(ca.2.0～ 1.8Ga)和中元古代早期(1.8～ 1.6Ga)三个阶段;(2)新太古代早期(ca.2.7～2.6Ga)和新太古代晚期(2.6～2.5Ga)是敦煌造山带大陆地壳形成的主要阶段;古元古代晚期(ca.2.0～ 1.8Ga)和中元古代早期(1.8～1.6Ga)主要是古老大陆地壳物质再循环阶段,也有少量新生陆壳物质的形成;(3)敦煌造山带前寒武纪结晶基底最初拼合事件可能发生在新太古代末期(～2.5Ga),之后经历了古元古代晚期(ca.2.0～1.8Ga)汇聚、碰撞造山过程,直到中元古代早期(1.8 ～ 1.6Ga),造山活动结束,前寒武纪结晶基底最终固结,进入稳定发展阶段;(4)前寒武纪结晶基底最终稳定固结之后,即～1.6Ga之后,敦煌前寒武纪结晶基底可能进入长达12亿年的静寂期,一直处于稳定状态,目前没有发现相关的岩浆-变质-沉积记录(类似于地盾状态),直至古生代志留纪开始活化(～440Ma),卷入古亚洲洋南缘俯冲、碰撞造山过程并被强烈改造.
