新疆巴里坤湖晚第四纪沉积地球化学特征与古气候

GEOCHEMICAL CHARACTERISTICS OF THE LATE QUATERNARY DEPOSITS IN THE BARIKUN LAKE OF XINGJIANG AND ITS RELATIONS WITH THE PALAEOCLIMATE

根据新疆巴里坤湖晚第四纪沉积的有机质、化学元素分布与古气候关系的讨论,得到如下结论:1.有机质和化学元素分布与生物地层旋回有很好的相关性,表明中纬度内陆干旱区存在着冷湿—暖干的气候格局,这一格局从晚更新世以来即制约着本区地球化学环境的发展。2.在干旱区封闭湖盆,有机质组成和化学元素组合变化主要受有效降水多寡(或湿度)的控制和影响,C/N、Sr/Ba和CaO/MgO比值均反映本区古气候变化具有周期性。3.多数化学元素和CaCO_3含量分布表明本区古气候自更新世以来向着干旱化波动发展。

According to the discussion on distribution of organic matter and chemical elements of the Lete Quaternary deposits in the Berikun Lake of Xinjiang, and on its relations with palaeoclimate, some ideas are given as follows. 1) Distribution of organic matter and chemical elements correlates well with the cycles of bio-stra tum cycles, and this means that the climatic pattern of alternating between moist-cold and dry-warm exists in inland arid ares in the middle latitudes, which has dominated the changes of geochemical envi ronment in the areas since the Late Plestocene. 2) In the closed Lake basin in arid region, changes of organic matter compositions and the chemi cal element combinations have been mainly controlled and influenced by the volume of effective precip itation(or moisture). Ratios of C/N, Sr/Ba and CaO/MgO reflect that the paleoclimate Variation in this region is periodic. 3) Distributions of most chemical elements and CaCO_3 content indicates that the paleoclimatic changes have been fluctually in tending to become in this region since the Late Pleistocene.