新疆塔县石头城一带中更新世冰碛物的发现及地质意义  

The Discovery of the Mid-Pleistocene Glacial Tills and Its Geological Significance in Taxkorgan Stone Town Region of Xinjiang

作　　者：边小卫 曾忠诚 朱海平 杨涛 孔文年 

机构地区：[1]陕西省地质调查中心,陕西西安710016

出　　处：《西北地质》2014年第4期131-140,共10页Northwestern Geology

基　　金：中国地质调查局项目"1:5万新疆塔什库尔干等7幅区域地质调查"(编号:1212011120527)资助

摘　　要：笔者首次在塔县的老兵站、石头城和加油站等3处发现了古冰碛物,均呈残留冰碛台地分布,台地高程约为3 100m,表面可见大量正长岩漂砾。漂砾风化穴的主要类型为边墙形、蜂巢型和底穴型。在侵蚀切割该古冰碛物的砂砾层中,得到(62.07±2.44)ka的光释光年龄。同时与附近墓士塔格山和公格尔山古冰川的对比研究,表明该冰碛物时代可能为中更新世倒数第二次冰期,为塔县县城西侧斯顿古冰川向东冰进的产物。该冰碛物的发现具有重要的地质意义:可将斯顿山第四纪冰川遗迹划分为中更新世的倒数第二次冰期、晚更新世的末次冰期,以及全新世的新冰期和小冰期;进一步指示塔什库尔干断裂的左行走滑正断层性质;更新世,斯顿古冰川与墓士塔格冰川各自有明确的界线,不可能形成一个统一的冰盖。The authors first found the three fossil glacial tills at the ancient army service station, stone town and gas station in Taxkorgan County. Geomorphic Types and distribution of the fossil glacial tills were the remaining glacial platform. The platform is about 3 100 m in height, and we can see a lot of glacial syenite boulders on it. The tafonis developed on glacial syenite boulders were classified into side-wall tafoni, basal tafoni, cellular tafoni according to their morphological characteristics and positions. Field geological investigation shows that the gravel cut down into the old moraine, and the OSL age of the gravel layer is （62.07 ~ 2.44） Ka. Contrastive study of the fossil glacial tills in stone town region and the glacial moraine in Muztag Ata-Konggur Moun- tain was carried out, it is showed that the fossil glacial tills formed in late penultimate glacial pe- riod of mid-Pleistocene, and derived from the glacier advance of paleo-glacier in the Sidun Mountain. The discovery of the mid-Pleistocene glacial tills has very important geological significance. （1） the authors divided the Quaternary glaciers in the Sidun Mountain into four ice ages, namely late penultimate glacial period of mid-Pleistocene and last glacial period of late Pleistocene, as well as neoglacial period and little Ice Age of Holocene; （2） the Taxkorgan fault are left-lateral strike-slip faults; （3） the clear bounds and limited scales of Pleistocene glaciations in the Sidun mountain and Muztag are incompatible with imagining a successive ice sheet on the Plateau.

关 键 词：新疆 塔什库尔干县 石头城 冰碛物 冰川 冰期划分 

分 类 号：P534.6[天文地球—古生物学与地层学] P512.4[天文地球—地质学]