罗布泊东部阿奇克谷地第四纪古地理

QUATERNARY PALAEOGEOGRAPHY OF AQIKE DEPRESSION, EASTERN LOP NUR,XINJIANG

对罗布泊东部阿奇克谷地中部AK1孔及露头剖面第四纪沉积特征进行了综合研究 ,初步分析了阿奇克谷地第四纪以来的沉积环境与古地理演化。结果表明 ,阿奇克谷地第四纪古地理受上新世以来区域构造控制 ,谷地两侧北山及阿尔金山的隆升 ,为其提供了丰富的物质来源 ,同时也控制了其沉积环境的演化。第四纪以来阿奇克谷地沉积环境有两次明显的变化。在早更新世中期谷地中开始出现湖相沉积 ,在中更新世晚期湖相沉积范围扩大 ,为罗布泊湖的大发展期。在晚更新世谷地两侧普遍出现砾石层 ,与中更新世沉积呈不整合接触 ,这表明构造抬升造成湖泊退缩。晚更新世以来湖泊沉积环境波动变化加快。

The sedimentary characteristics of Quaternary around Aqike Depression in eastern Lop Nur area have been studied, and the sedimentary environments and palaeogeographic evolution of Aqike Depression since Quaternary have been analysed. It is showed that the Quaternary palaeogeography of Aqike Depression was controlled by the regional tectonic framework since Pliocene. The uplift of Beishan and Altun Mountains along both sides of Aqike Depression controlled the development of depositional system, and was the main source provenance. The distribution of lake sediments around Aqike Depression had two stages of enlargement during Quaternary. Two high levels of the lake were discovered from middle Early Pleistocene and late Middle Pleistocene of AK1 core, eastern Lop Nur area.The occurrence of lake sediments in Bayi Spring section of the late Middle Pleistocene means the climax of Lop Nur Lake during Quaternary. The tectonic uplift resulted in a persistent regression as indicated by the conglomerate layer during Late Pleistocene. The environment of the Lop Nur Lake was fluctuant since Late Pleistocene.