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通过对天水盆地新近纪沉积物地化特征的研究表明:(1)天水盆地下山剖面泥岩富MgO、CaO、Nb、Sr、Th,贫SiO2、Al2O3、Ba、Cr、Ni、Rb,高Al2O3/TiO2、Cr/Zr、Cr/Th、Th/Sc,结合盆地的平面展布特征和地层厚度变化规律及沉积相的横向变化,初步认为盆地南区西秦岭北缘各时代花岗闪长岩和偏中性岩主要控制着该区的沉积物地球化学组成,而古秦岭洋闭合期蛇绿岩套中的基性-超基性岩有很大的影响,其结果是它们高度混合的物质给盆地提供物源,泥岩样品中K2O的含量随时间增长而增高,说明物源区在溯源侵蚀的过程中富钾值岩大量出现;(2)CIA和ICV值指示天水盆地碎屑沉积物的物源区古风化程度较强,沉积物成熟度较低,源区沉积再循环的物质很少或几乎不存在,在上新世到更新世之间存在化学风化作用减弱的趋势;(3)天水盆地从西秦岭山麓到华家岭地层沉积厚度越来越薄,从湖相逐渐过渡为湖泛平原相,结合主、微量元素构造判别图解,认为下山剖面沉积物是在压扭作用下的山前凹陷盆地构造环境中形成。
Through the study of the sedimentary geochemistry of the Neogene in the Tianshui Basin, it is shown that: (1) the mudstone in the downhill section of the Tianshui Basin is rich in MgO, CaO, Nb, Sr, Th, SiO2, Al2O3, Ba, Cr, Ni, In the northern part of the western Qinling Mountains, the granodiorite and granodiorites in the northern margin of the western Qinling Mountains in the south of the basin and the sedimentary facies in the south of the basin, Metoclastic rocks dominate sedimentary geochemistry in the area, whereas the mafic-ultrabasic rocks in the closed-age ophiolite suite of the ancient Qinling have a large effect, with the result that their highly mixed materials The K2O content of mudstone samples increases with time, which indicates that a large amount of potassium-rich rocks occur in the source area during trace-source erosion. (2) The CIA and ICV values indicate the source of clastic sediments in the Tianshui Basin There is a strong degree of paleoclimate in the area, with low maturity of sediments and little or no recourse of sediments in the source area. There is a tendency that chemical weathering weakens between Pliocene and Pleistocene. (3) From the West Qinling foothills to Huajialing stratigraphic deposition thickness thinner and thinner, from lake to lake The gradual transition to the lake plain phase, combined with the main trace element structure diagram, that the down-section sediment is formed in the piedmont potholder basin tectonic environment.