中纬度造山带地区的长期化学风化——中亚和北美的对比研究  

Long-term chemical weathering in mid-latitude orogenic belt:A comparative study of Central Asia and North America

作　　者：孙晨 朱秉启[1] SUN Chen;ZHU Bingqi(Key Laboratory of Water Cycle and Related Land Surface Processes,Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院地理科学与资源研究所,陆地水循环及地表过程重点实验室,北京100101 [2]中国科学院大学,北京100049

出　　处：《地质学报》2024年第6期1880-1892,共13页Acta Geologica Sinica

基　　金：国家自然科学基金重点项目(编号41930640);第三次新疆综合科学考察项目(编号2021XJKK0803);第二次青藏高原综合科学考察研究项目(编号2019QZKK1003)联合资助的成果。

摘　　要：长期化学风化速率(LCWR)和化学风化剥蚀率(CDF)是表征区域化学风化程度和揭示地貌和气候系统演变的重要依据。全球尺度上,中纬度地区的长期化学风化研究远比低纬地区争议更多,原因之一是其风化机制在理论认识上仍存在不确定性,特别是造山带地区的长期化学风化与物理侵蚀、构造、气候之间的关系等。本文利用地球化学质量平衡方法,针对北半球中纬度典型造山带(中亚黑河流域和北美内华达山脉)开展了相关数据和资料的系统整理与再分析,估算了黑河流域的LCWR值和物理侵蚀速率(E)值并与内华达山脉进行了对比研究。分析结果表明,黑河流域、内华达山脉的LCWR分别为17.4~895t/km^(2)/a、1~173t/km^(2)/a,CDF分别为0.17~0.81、0.02~0.61,LCWR与E均显著正相关,与海拔高度、年均温度、年均降水量等仅局部相关。研究区的长期化学风化主要表现为“供应受限型”风化,但黑河流域局部地区已处于“供应受限”与“动力学受限”过渡的风化阶段。结合回归分析结果和已有成果的综合分析,中纬度造山带地区的长期化学风化速率受到地质、气候等因素的协同影响,但主控因素为地质因素,而化学风化剥蚀率则主要受控于其他因素。Long-term chemical weathering rate(LCWR)and chemical depletion fraction(CDF)are important parameters to characterize the degree of regional chemical weathering and reveal the evolution of landforms and climate.On a global scale,studies of long-term chemical weathering in mid-latitude areas are far more controversial than those in low-latitude areas.One of the reasons is that there is still uncertainty in theoretical understanding of their weathering mechanisms,especially the relationship between long-term chemical weathering and physical erosion,structure and climate in orogenic belt areas.In this paper,the geochemical mass balance method is used to systematically sort out and reanalyze the relevant data and materials for the typical mid-latitude orogenic belts in the northern hemisphere(the Heihe River basin in Central Asia and the Sierra Nevada in North America),estimate and compare their LCWR and physical erosion rate(E)values.The results show that the LCWRs of the Heihe River basin and Sierra Nevada are 17.4~895 t/km^(2)/a and 1~173 t/km^(2)/a,respectively,and the CDFs are 0.17~0.81 and 0.02~0.61,respectively.LCWR is positively correlated with E,and only partially correlated with altitude,average annual temperature and average annual precipitation.The long-term chemical weathering in the study area is mainly characterized by“supply-limited”weathering,but some areas in the Heihe River basin have been in the transitional stage of“supply-limited”and“kinetically-limited”.Combined with the results of regression analysis and the comprehensive analysis of existing data,it is found that the long-term chemical weathering rate in mid-latitude orogenic belt is influenced by geological and climatic factors,but the main controlling factor is geological,while the chemical depletion fraction is mainly controlled by other factors.

关 键 词：长期化学风化速率 化学风化剥蚀率 物理侵蚀速率 地球化学质量平衡方法 中纬度造山带 

分 类 号：P512.12[天文地球—地质学]