摘要
为重建新疆其木干地区中新世-上新世古气候,采用X射线衍射、扫描电子显微分析方法,对该区中新世-上新世沉积物中粘土矿物的相对含量、组合类型及显微形貌等进行了研究。结果显示:中新世早期-早中新世中期,沉积物中粘土矿物以伊利石和绿泥石为主,含少量的蒙脱石,表明以干旱气候为特征;晚中新世中期-早中新世晚期,伊利石的相对含量逐渐降低,且含有少量的蒙脱石和高岭石,指示相对温湿的气候条件;中新世晚期的粘土矿物组分与中新世早期相似,以伊利石和绿泥石为主,指示古气候以干旱为主导;晚中新世晚期至上新世伊利石相对含量降低,而蒙脱石和高岭石的相对含量升高,但由于粘土矿物中伊利石、绿泥石的含量仍然较高,指示古气候仍然以干旱为主导,但相对于中新世而言,这段时期为相对湿润期。以上结果表明,新疆其木干地区中新世-上新世古气候以干旱为主,并且气候经历了干旱-相对湿润-干旱-相对湿润的演化过程,但总体而言,本区中新世比上新世要更为干旱。
To reconstruct the palaeoclimte of Miocene-Pliocene in Qimugan of Xinjiang, sediments were collected, and their clay minerals relative proportion, assemblage, and micromorphology were determined by the methods of X-ray diffraction （XRD） and scanning electron microscopy （SEM）. In early Miocene-early mid Miocene sediments, illite and chlorite were the main clay minerals, and montmorillonite was minor, indicating an arid palaeoclimate prevailed over the period. In late mid Miocene-early late Miocene sediments, illite content decreased slightly, and montmorillonite and kaolinite were minor, suggesting a relatively warm and humid palaeoclimate. The mid late Miocene sediments had the similar clay minerals assemblage as the early Miocene sediments, suggesting the similar climate conditions to the early Miocene age. In late late-Miocene-Pliocene sediments, illite content exhibited a decrease trend, while montmorillonite and kaolinite contents were in reverse, suggesting a relatively warm and humid palaeoclimate. However, the abundant illite and chlorite throughout the Miocene-Pliocene sediments in Qimugan of Xinjiang indicated a general cold and dry climate during the period, and the palaeoclimate experienced two cycles of cold and dry to relatively warm and humid, and the climate of the Miocene was drier than that of the Pliocene.
出处
《生态学杂志》
CAS
CSCD
北大核心
2010年第5期923-932,共10页
Chinese Journal of Ecology
基金
国家自然科学基金项目(40872038)
中国地质调查局项目(1212010610103)
地质过程与矿产资源国家重点实验室开放课题基金资助项目(GPMR200910)
关键词
西昆仑山
中新世-上新世
前陆盆地
粘土矿物
古气候
west Kunlun Mountains
Miocene-Pliocene
foreland basin
clay mineral
palaeoclimate
