Relationship between continental chemical weathering trends in the North China Basin and the high-latitude glacial cycles from the Late Carboniferous to the Early Permian
凌紫玉杨敏芳王雷王野张培新刘昊青邵龙义鲁静
LING Ziyu;YANG Minfang;WANG Lei;WANG Ye;ZHANG Peixin;LIU Haoqing;SHAO Longyi;LU Jing
中国矿业大学(北京) 地球科学与测绘工程学院 煤炭精细勘探与智能开发全国重点实验室中国石油勘探开发研究院中石油煤层气有限责任公司沈阳建筑大学 土木工程学院河南城建学院 市政与环境工程学院 河南省绿色低碳水处理技术与水资源利用国际联合实验室
晚古生代冰室期(LPIA;
结果显示,低纬度柳江煤田的大陆化学风化作用的周期性变化,包括巴什基尔阶早−中期、莫斯科阶−卡西莫夫阶、阿瑟尔阶早期的3个风化减弱阶段和巴什基尔阶晚期、格舍尔阶的2个风化增强阶段。这种风化趋势的循环交替与高纬度冈瓦纳大陆的冰川旋回密切相关:风化趋势的减弱阶段代表了气候条件向相对凉爽干燥转变,这几乎与高纬度冰期同步,而风化趋势的增强阶段则代表了气候条件向相对温暖湿润的变化,这与高纬度间冰期同步。对比分析发现,间冰期内火山活动频发、大气CO2浓度升高、气候变暖、水文循环增强、海平面上升,共同促进了热带雨林面积缩减和大陆化学风化作用增强,为铝土矿的发育创造了有利条件;而冰期内火山活动减弱、气候变凉、CO2浓度减少、雨林面积扩张,导致大陆风化作用减弱,有利于煤和富有机质泥岩形成。
研究结果揭示了低纬度华北盆地大陆化学风化趋势与高纬度冈瓦纳冰川旋回和沉积矿产(如煤、铝土矿)分布之间的联系,为理解地质历史时期冰川−环境−气候的复杂相互作用机制提供了新视角。
The Late Paleozoic Ice Age (LPIA; ca. 360‒254 Ma), the only period recording the transition from icehouse to greenhouse conditions throughout the geological history, can provide a deep-time perspective for glacier-environment-climate coevolution and future climate change. To gain a deep understanding of the potential relationship between the continental chemical weathering trends in low-latitude regions and the glacial cycles in the high-latitude Gondwana region from the Late Carboniferous to the Early Permian, this study investigated the mudstones of the Benxi-Taiyuan formations, Liujiang coalfield, North China Basin. Using multiple chemical weathering indices such as chemical index of alteration (CIA), chemical index of weathering (CIW), and plagioclase index of alteration (PIA) calculated from the elemental geochemical data of the mudstones, this study reconstructed the continental chemical weathering trends and paleoclimatic evolutionary characteristics of the Liujiang coalfield.
The results indicate that the periodic changes of continental chemical weathering in the low-latitude Liujiang coalfield involved three weathering weakening stages (i.e., early-middle Bashkirian, Moscovian-Kasimovian, and early Asselian) and two weathering enhancement stages (i.e., late Bashkirian and Gzhelian). This cyclic alternation of weathering trends was closely associated with the glacial cycles of the high-latitude Gondwanaland. The weathering weakening stages represent shifts to relatively cool and dry climates, roughly synchronous with the glacial periods at high latitudes. In contrast, the weathering enhancement stages suggest changes to relatively warm and humid climates, coinciding with the interglacial periods at high latitudes. The comparative analysis reveals that frequent volcanic activity, increased atmospheric CO2 concentration, climate warming, enhanced hydrologic cycles, and sea-level rise during the interglacial periods jointly contributed to the reduced area of tropical rainforests and the enhanced continental chemical weathering, creating favorable conditions for the formation of bauxite. In contrast, the weakening volcanic activity, cooling climate, reduced atmospheric CO2 concentration, and increased rainforest area during the glacial periods led to weakened continental weathering, facilitating the formation of coals and organic-rich mudstones.
The results of this study reveal the relationship between the continental chemical weathering trends in the low-latitude North China Basin and the glacial cycles and the distributions of sedimentary minerals (e.g., coals and bauxite) in the high-latitude Gondwana region, providing a novel perspective for understanding the mechanisms underlying complex glacier-environment-climate interactions throughout the geological history.
晚古生代华北盆地化学风化CIA冰期间冰期
Late Paleozoic Era;North China Basin;chemical weathering;chemical index of alteration (CIA);glacial period;interglacial period
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会