华南晚前寒武纪剪刀式开合构造及其动力学

LATE PRECAMBRIAN SCISSORS-TYPE OPENING-CLOSING TECTONICS AND ITS DYNAMICS IN SOUTH CHINA

本文综述了近10年来华南地区前寒武纪地质研究的6项重大进展后,提出了该区晚前寒武纪剪刀式开合构造演化的新设想:(1)华南地区除存在中、晚元古代浅变质基底外,还存在晚太古宙—早元古代中—深变质基底,并在早元古代未形成统一的扬子—华夏古陆,但古陆的东北部有一伸入古陆内部的赣皖浙古海湾,海湾北侧是赣皖苏半岛;(2)从中元古代起,古陆中西部,即现今的桂黔湘地区张裂成裂陷槽,使“华夏块体”逆时针转动和“扬子块体”顺时针转动,加之大别—胶南块体从华北板块脱落、增贴到赣皖苏半岛北缘的南向挤压作用,遂导致赣皖浙古海湾的剪刀式闭合,进而影响到该区显生宙构造演化。

In the paper the author first reviews 6 major advances in Precambrian geology in South China during the last decade, and then proposes the following new model of Late Precambrian scissors-type opening-closing tectonic evolution in the area. (1) Besides the Middle-Late Proterozoic low-grade metamorphic basement, there existed the Late Archaean-Early Proterozoic medium-and high-grade metamorphic basement in South China; both of them formed the united Yangtze-Cathaysia (craton) by the end of the Early Proterozoic, with the Jiangxi-Anhui-Zhejiang Palaeogulf extending into its inland and the Jiangxi-Anhui-Zhejiang Peninsula lying on the northeastern side of the palaeogulf. (2) Since the Middle Proterozoic, the present Guangxi-Guizhou-Hunan area in the western-central oldland was subjected to extensional rifting and became a rift trough, thus resulting in counterclockwise rotation of the 'Cathaysian block' and clockwise rotation of the 'Yangtze block'; moveover, the southward compression of the Dabie-Jiaonan block which split from the southern margin of North China Craton and was accreted to the northern margin of the Jiangxi-Anhui-Zhejiang Peninsula led to the scissors-type closing of the Jjangxi-Anhui-Zhejiang Palaeogulf during the middle-early Late Proterozoic, which further influenced the Early Palaeozoic tectonic evolution of the area.