淮北煤田南部新生界底部松散沉积物沉积特征及古地理意义

SEDIMENTARY CHARACTERISTICS AND PALAEOGEOGRAPHIC SIGNIFICANCE OF THE LOOSE SEDIMENTS AT THE LOWERMOST PART OF THE CENOZOIC STRATA IN THE SOUTHERN HUAIBEI COALFIELD

关键词:  松散沉积物  碎屑结构  古地理  淮北

Key words:  loose sediments  clastic texture  palaeogeography  Huaibei

摘要:

通过对淮北煤田南部新生界底部松散沉积的沉积特征研究,初步得出结论,位于同一煤田的宿县矿区和临涣矿区的沉积物结构和矿物成份特征差别较大,导致这一差别的主要原因是物源区与岩性的不同,以及古地理条件的差别。在临涣矿区,以石英、长石和少量碳酸盐矿物组合以及以锫石、电气石为主的重矿物组合,反映了来自于矿区北部的中性闪长岩岩体的风化。而以含大量灰岩砾石,和以石英、燧石为辅的碎屑组成则说明了宿县矿区东部、北部奥陶系地层和煤系地层本身遭受了强烈风化。沉积物的复杂结构特征和矿物成份特征反映了基岩地貌南低北高,源区遭受的强烈物理风化作用以及在短距离内快速搬运和多源沉积特征。

Abstract:

There are large discrepancies in sedimentary textures and structures and mineral com-positions of the sediments from the Xuxian and Linhuan mining districts although in the same coalfield,as revealed by sedimentary characteristics of the loose sediments at the low-ermost part of the Cenozoic strata in southern Huaibei coalfield.The authors owe these dif-ferences to different provenances,lithology and palaeogeographic environments in respec-tive mining districts.For instance,the sediments in the Linhuan mining district consist mainly of quartz,feldspar and carbonate minerals plus the heavy mineral assemblages dom-inated by zircon and tourmaline vindicating that the detritus were derived from the weather-ing products of the neutral diorite massifs in the north of the mining district,while in the Xixian mining district,the sediments are characteristic of a large amount of limestone grav-els plus subordinate quartz and chert,suggesting that the principal sources of detritus lay to the Ordovician strata and intensely weathered coal measures in the east and north of the mining district. The complex textures and structures and mineral compositions of the sediments show higher bedrock topography in the north of the mining districts,intense physical weathering of the source rocks,short-distance and faster transport,and polyphyletic origins.