第一节研究简史峡东地区位于上扬子地台北缘,黄陵背斜核心部分(图2—1)。本区有前震旦纪至第四纪地层出露,除前震旦纪有花岗岩侵入外(花岗岩 Rb—Sr 全岩等时线年龄819±54百万年),其后未见岩浆活动形迹。本区构造简单,黄陵背斜近南北向,核部由前震旦纪结晶基底组成,围绕震旦纪至三叠纪地层;背斜东翼平缓,倾角约8—112度,西翼较陡,倾角可达30—40度。 Section I Brief History of Research The Xiaodong area is located in the northern margin of the upper Yangtze platform and the core part of the Huangling anticline (Figure 2-1). Exposed to the Pre-Sinian to Quaternary strata in this area, except for the granulite intrusions in the Pre-Sinian period (the granitic Rb-Sr whole-rock isochron age is 819 ± 54 million years), no magmatic activity was observed thereafter. The structure of this area is simple. The Huangling anticline is nearly north-south direction. The core is composed of pre-Sinian crystalline basement and surrounds the Sinian to Triassic strata. The anticlinal east wing is gentle with a dip angle of about 8-112 degrees and a steeper west wing , Tilt up to 30-40 degrees.