邓旭升, 余文超.贵州西部地区早三叠世异常沉积和风化作用[J].河南理工大学学报（自然科学版）,2025,44(5):121-131.

DENG X S, YU W C.Anomalous Early Triassic sedimentation and weathering in western Guizhou[J].Journal of Henan Polytechnic University(Natural Science) ,2025,44(5):121-131.

贵州西部地区早三叠世异常沉积和风化作用

邓旭升1, 余文超2

1.贵州省地质调查院，贵州 贵阳  550081；2.中国地质大学（武汉） 地球科学学院，湖北 武汉  430074

摘要: 目的 为了揭示贵州威宁地区早三叠世沉积和风化作用的特征及其变化，开展贵州西部地区早三叠世异常沉积和风化作用研究。  方法 对威宁地区下三叠统碎屑岩开展厚度统计、岩相学和全岩地球化学分析，并与研究区及邻区上二叠统进行对比分析。  结果 结果表明，威宁地区早三叠世印度期（251.902 Ma—251.2 Ma）沉积了大量来源于峨眉山玄武岩风化剥蚀的碎屑物质，该时期平均沉积速率高达786 m/Ma，表现为异常而快速的沉积输入特征。此外，早三叠世印度期沉积速率是晚二叠世的33倍，指示沉积作用明显变化。该地区下三叠统碎屑岩中w（Y）/w（Ho）略低于源岩，具有低IOL/IOB，CIA和MIA（o），明显低于该地区及其邻区上二叠统碎屑岩，表现为微弱的化学风化作用。  结论 在早三叠世炎热气候和弱化学风化作用背景下，异常高的沉积速率应与该时期异常强烈的物理剥蚀及风化作用有关。这可能是对二叠纪末生物大灭绝导致的陆地森林系统大量消亡、水圈循环的强化和大范围干旱等极端地质事件的沉积响应。

关键词:早三叠世;风化作用;沉积作用;碎屑岩

DOI:10.16186/j.cnki.1673-9787.2024110001

基金项目:国家重点研发计划项目（2022YFF0800200）；贵州省地质矿产勘查开发局地质科研项目（黔地矿科合［2020］31号）

收稿日期:2024/11/01

修回日期:2025/01/16

出版日期:2025/07/23

Anomalous Early Triassic sedimentation and weathering in western Guizhou

Deng Xusheng1, Yu Wenchao2

1.Guizhou Geological Survey， Guiyang  550081， Guizhou， China；2.School of Earth Sciences， China University of Geosciences （Wuhan）， Wuhan  430074， Hubei， China

Abstract: Objectives To reveal the early Triassic sedimentary and weathering characteristics and changes in the Weining area， Guizhou，conduct research on Early Triassic abnormal sedimentation and weathering in western Guizhou.  Methods the thickness， petrography and geochemistry of the lower Triassic clastic rocks were analyzed， and were compared with those of the upper Permian in the study and adjacent areas. Results In the early Triassic Induan， a large amount of the detrital materials from the Emeishan basalt were deposited in Weining area， and the average sedimentation rate during this period was as high as 786 m/Myr， which showed the anomalous and rapid deposition. In addition， the early Triassic Induan sedimentation rate was 33 times that of the late Permian， indicating a significant change in sedimentation. The lower Triassic clastic rocks had slightly lower w（Y）/w（Ho） value than that of the source rocks， with low LOL/IOB values， CIA and MIA（o）values， which were obviously lower than that of the upper Permian clastic rocks in this area and its adjacent areas， showing weak chemical weathering.  Conclusions Under the background of hot climate and weak weathering in the early Triassic， the anomalous and high sedimentation rate should be related to the strong physical denudation and weathering in this period. This could be a sedimentary response to extreme geological events such as the mass extinction of terrestrial forest systems， the strengthening of hydrosphere cycles and widespread drought caused by the end-Permian mass extinction.

Key words:early Triassic;weathering;sedimentation;clastic rock