扬子克拉通北西缘碧口群的解体与地层划分

DECOMPOSITION AND STRATIGRAPHIC SUBDIVISION OF BIKOU GROUP IN NORTHWESTERN MARGIN OF YANGTZE CRATON

碧口群组成十分复杂．论述了对其解体的必要性；解体出了包括鱼洞子花岗绿岩地体周缘的稳定陆缘沉积建造、扬子地台北西缘古元古代陆间裂谷型火山－沉积建造、中元古代洋壳残片及深海沉积物和新元古代的火山弧前盆地堆积、新元古代的残留地中海式堆积以及造山后的山间盆地堆积等众多不同性质的构造地层单元；

The stratigraphy in Bikou Group is rather complicated. The present paper deals with the necessity of the stratigraphic decomposition. Several distinctive tectono_stratigraphic units are defined through the decomposition. These units include the passive continental margin type of sedimentary formation around Yudongzi granite_greenstone terrain; the Paleoproterozoic intercontinental rift type of volcano_sedimentary formation along northwestern margin of Yangtze craton; the Mesoproterozoic oceanic crust residues and abyssal sediments as well as the Neoproterozoic fore_arc basin sediments; the Neoproterozoic Mediterranean sediments and post_orogenic inter_mountainous basin sediments. This paper also presents the preliminary discussion on their formation history.