安徽南部石炭纪的构造与古地理

TECTONICS AND PALAEOGEOGRAPHY OF SOUTHERN ANHUI DURING THE CARBONIFEROUS

摘要:

古地理、构造轮廓下扬子区的安徽部分,由于受华力西运动的影响,以及成生时代尚不清楚的沿江断裂与形成于加里东早期的江南深断裂的控制,在早石炭世岩关晚期形成“三隆两坳”的古地理格局(图1)。

Abstract:

The Carboniferous sediments in southern Anhui were controlled by "three rises and two depressions", synsedimentary faults along the Yangtze River and the Jiangnan fault, The Chaoxian—Lu-jiang and Xuancheng—Jingxian bays were created during the Early Carboniferous, and the differentiation of sedimentary facies belts occurred during the Late Carboniferous. The study of seven time-equivalent sedimentary facies indicates that the sea level changes and distribution of the sedimentary facies belts were closely related to synsedimentary faulting. The above-mentioned bays were of shallow-water type during the early Datangian, but during the late Datangian, the deposition took place only in the Chaoxian—Lujiang bay. Meanwhile, synsedimentary faulting operating intermediate between southern and northern Chaoxian—Lujiang bay was responsible for the differences in the two facies belts: shelf facies in the northern part and tidal flat-lagoon facies in the southern part. By the end of the Carboniferous, structural activities had led to the formation of land, marginal bank and intraplatform shoal.
Two sporo-pollen assemblages have been distinguished in the Tongling peninsula with the aid of biostratigraphic analysis: (1) Retispora lepidophyta vat. minor-Apiculiretusispora nunanensis-Cymbosporites assemblage zone and (2) Dibolisporites distinctus-Auroraspora macra-Scnopfites claviger assemblage zone. This strongly supports the evidence that the Gaolishan Formation in the Tongling region would be ascribed to the early Yanguanian strata. The study of sedimentary facies also shows that there is no marginal facies around the Tongling peninsula, the existence of which may be confirmed by the diachronous cover dolostones.