青藏高原北缘前寒武纪地质演化：进展与讨论

青藏高原北缘前寒武纪块体主要出露于塔里木盆地南缘的铁克里克和阿尔金、祁连山及柴达木盆地周缘等地区。这些古老块体分布于相对年轻的古生代秦祁昆造山带之中，大多经历了古生代造山事件的改造叠加。近10年来，对该地区前寒武纪地层时代格架、物质组成和构造属性研究取得了许多进展：1）揭示铁克里克、北阿尔金、全吉和阿拉善地块具有相似的2.5～2.2 Ga、2.1～1.7 Ga的基底演化和1.7 Ga之后的盖层沉积记录，反映塔里木克拉通、全吉地块和华北克拉通在Columbia 超大陆中具有相关和相似性。2）一系列地层时代被重新厘定，为建立新的前寒武纪地层划分方案提供了依据；3）厘定出铁克里克新元古代裂谷火山—沉积盆地，其可以与华北克拉通南缘1 000～830 Ma的裂解事件对比，它们在新元古代早期可能构成同一个克拉通裂解边缘；4）在南阿尔金与祁连、柴达木等地块识别出性质相似的新元古代岩浆作用和变质作用，它们可能共同代表一个新元古代早期活动大陆边缘的构造杂岩，为古生代汇聚、增生于塔里木克拉通或华北克拉通南缘的外来地块，存在于秦祁昆造山带之中。目前关于青藏高原北缘前寒武纪块体的物质组成、时代格架、构造属性和古环境变化研究还存在许多问题，仍需要开展进一步的大量工作。

Precambrian geology of the northern margin of the Tibetan Plateau: Review and discussion

There are many Precambrian blocks outcrop at the Tiekelike, Altyn Tagh, Qilian Shan, Qaidam and its surroundings along the northern margin of the Tibetan Plateau. All these old blocks were distributed in the Qiling-Qilian-Kunlun orogenic belt and reworked by Palaeozoic orogenesis. Recent studies on the chronostratigraphic frameworks, lithological associations and tectonic affinities of these Precambrian blocks indicate that: 1）There are identical 2.5～2.2 Ga and 2.1～1.7 Ga tectonothermal and post ～1.7 Ga sedimentary events in the Tiekelik, North Altyn-Dunhuang, Alashan blocks, and Quanji massif, which are likely related to the dispersal of Neoarchaean‘Kenorland’and the formation of the Columbia supercontinent. 2）Many chronostratigraphic frameworks were revised and the new Precambrian lithostratigraphic division of the Tiekelike belt was proposed. 3）A Neoproterozoic volcano-sedimentary rift basin was suggested to have developed along the southwestern margin of the Tarim Craton. The occurence of ca. 1 000～830 Ma rift-related volcanic rocks unraveles Neoproterozoic regional extensional processes in the southern margin of the Tarim-North China Craton, which allow us to speculate on the correlation of the Tarim and North China Cratons during the Neoproterozoic. 4）The similarities of magmatism and metamorphism ages in the Altyn Tagh-North Qaidam-Qilian-East Kunlun suggest that extensive early Neoproterozoic tectonic complexes had developed along the northern margin of the Tibetan Plateau. These complexes may represent exotic fragments accreted to the Tarim Craton during the Palaeozoic.