中朝板块南缘的滑塌堆积及其构造环境

陕西商洛及河南卢氏、栾川地区上元古界和下古生界地层中发育有滑塌堆积物,其主要类型包括岩崩、滑动、滑塌和沉积物重力流,其中后者主要见到碎屑流、颗粒流和浊流沉积。它们多从下到上构成了由粗到细由浅水到深水的退积序列,呈海相扇三角洲沉积在晚元古代冰川边缘及早古生代碳酸盐台地边缘的两种大陆斜坡上,其沉积特征反映了中朝板块南缘从晋宁期到早加里东期呈强烈抗张断陷的大陆边缘环境。

OLISTOSTROMES AND TECTONIC SETTINGS IN THE SOUTHERN MARGIN OF THE SINO-KOREAN PLATE

In the middle part of the southern margin of the Sino-Korean Plate ( Shangxian and Luoaan Counties, Shaanxi and the Lushi and Luanchuan areas, Henan ) , there are clearly sedimentary characteristics of olistostromes in the Sinian Luoquan Fm., Dazhuang Fm. and Baishugou Fm. and Lower Paleozoic Taowan Group. It is recognized that the main types of submarine mass transport in olistostrome are: rockfall, slide, slump and sediment gravity flows, in which the later comprise debris flow, grain flow and turbidite current. There are many traces of glaciation in the Sinian gravity flow deposits in the northern part of the studied region. The sequence here is from the lower glacial terrigenous debris flows to the upper high-density turbidite current deposits. In the southern part, no glacial features are discovered. The sedimentary sequences of the Sinian are mostly from the debris flow to the turbidite current. The sequence that slump and slide sedimentary sequence of the Early Paleozoic olistostrome is mainly composed of lower slump and slide, middle debris flow and upper turbidite current containing grain flow in some sections. The Sinian and Early Paleozoic sequences are two trans- gressive ones. The olistostromes deposited separately on the continental slopes which connected with edge of the glacier during the Sinian and of the carbonate platform in fan-deltas during the Early Paleozoic era. Their sedimentary sequences and the phase distribution indicate that the region was in extensional tectonic settings of the divergent margin, the faulting of which took place during the Later Proterozoic era to the Early Paleozoic era