龙门山南段青衣江阶地沉积物的化学风化特征及其意义  

The chemical weathering and its south range significance of Qingyi River terraces, of Longmen Shan

作　　者：姜大伟[1] 张世民[2] 丁锐[2] 李伟[2] 刘汉永[2] 郭萌[2] 

机构地区：[1]中国地震局地质研究所,北京100029 [2]中国地震局地壳应力研究所,北京100085

出　　处：《地质科学》2016年第3期763-778,共16页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金项目（编号：41272234）资助.

摘　　要：本文通过对龙门山南段青衣江阶地的研究，尝试以常量元素所体现的风化特征，来解决阶地对比的问题，并取得了一定的进展。通过主量元素的分析，发现CIA指标、A-CN—K三角模型等，在区分不同年龄的阶地有很好的效果，而且沉积物砾石之间的基质颜色也一定程度地反映了新老关系。结合流域内更古老洪积扇的研究，发现河流阶地在距今200ka内化学风化速度较稳定，但更老的地貌面风化呈现非线性。另外，在本文研究的600ka时间尺度内，阶地风化速度与全球气候变化相关，体现为冰期风化速度慢，间冰期风化速度快，并具一定的滞后效应。Based on the research of Qingyi River terraces, locating in the southern range of the Longmen Shan, weathering characteristics calculated with major elements are discussed to solve the problem of terraces contrast, and some progress has been made. By analyzing the major elements, CIA index, A-CN-K triangular model are texted in order to distinguish terraces with different ages, which is proved to make sense. And the color of matrix in fluvial deposition is able to tell the difference of terraces to a certain extent. With the help of research about the alluvial fan formed by ancient Qingyi River, it is found that the rate of chemical weathering is smooth, but the older geomorphic surface weathering is nonlinear. Additionally, within 600 ka time scale of this study, terraces weathering rate is influenced by global climate change, the main performance is a low weathering rate in during an glacial epoch and, on the contrary, a fast weathering rate during an inter-glacial epoch. As an addition, the effect lags behind the change of climate.

关 键 词：龙门山 青衣江 阶地 洪积扇 常量元素 风化 气候 阶地对比 

分 类 号：P594[天文地球—地球化学] P595[天文地球—地质学]