新疆喀喇昆仑山地区泥盆纪地层划分与特征
Division and characteristics of Devonian strata in the Karakorum Mountains area in Xinjiang
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摘要: 在新疆西昆仑地区1:5万区域地质调查中,对分布于喀喇昆仑山地层区中的泥盆纪地层,开展剖面测量和区域填图,系统收集其岩性岩相、岩石组合、分布特征、接触关系、生物化石、基本层序等资料,并展开了多重地层划分与对比研究。研究表明区内泥盆纪地层由中下统大王顶组,中统黄羊滩组、落石沟组和上统天神达坂组组成,各组之间均为整合接触关系,除天神达坂组未获生物化石外,其他层位均获有丰富的古生物化石。其中新建大王顶组和黄羊滩组2个岩石地层单位,以及腕足类3个、珊瑚类1个、菊石类1个、三叶虫类1个,共计6个生物地层单位。全面系统厘定和完善了区内泥盆纪的岩石地层序列、生物地层序列和年代地层序列,黄羊滩组是重要的铜矿和石膏矿赋矿层位。从而极大地提高了喀喇昆仑山地区泥盆纪地层研究程度,也为本区地质构造演化和成矿规律分析提供了必要地史资料。Abstract: This paper describes the geological results of 1:50000 geological survey conducted in the West Kunlun Mountains area in Xinjiang. The data were obtained by using profiling and regional geological mapping methods on the Devonian strata of the Karakorum Mountains stratigraphic region. New data concerning lithology and lithofacies, rock association characteristics, contact relationship, biological fossil and the basic sequence were collected. Multiple stratigraphic division and correlation were studied. The Devonian strata were divided in upward succession into Dawangding Formation (Middle- Lower Devonian), Huangyangtan Formation (Middle Devonian), Luoshigou Formation (Middle Devonian) and Tianshendaban (Upper Devonian) Formation, exhibiting comfortable contact relationships. Abundant fossils were found in the Devonian strata except Tianshendaban Formation. Two new formations (Dawangding and Huangyangtan) and six new biostratigraphic units (comprising 3 brachiopoda units, 1 coral unit, 1 ammonite unit, and 1 trilobita unit) were established. Huangyangtan Formation is the major regional ore-bearing bed with gypsum. The lithostratigraphic sequence, biostratigraphic sequence and chronostratigraphic sequence of the Devonian strata in the working area were newly redefined and improved systematically. The study has not only improved the research degree of the Devonian strata in the Karakorum Mountains area but also offered necessary geological history data for the analysis of the geotectonic evolution and the metallogenic regularity in the working area.