西北地质2025，Vol.58Issue(5)：140-150,11.DOI:10.12401/j.nwg.2024127
哀牢山构造带南段早泥盆世硅质岩形成环境及大地构造意义
Depositional Environments and Tectonic Background of the Early Devonian Cherts of Southern Ailaoshan Tectonic Belt
摘要
Abstract
There is still a debate about whether the Jinshajiang Ailaoshan tectonic belt developed in the Late Paleozoic was a Paleo Tethyan Ocean or a backarc basin.This paper conducts petrographic and geochemical analyses of the Lower Devonian siliceous rocks in the southern section of the Ailaoshan tectonic belt in order to provide new evidence for the tectonic evolution of the area.The geochemical characteristics of siliceous rocks show that they are biogenic,with a significant negative correlation between SiO2 and Al2O3,and SiO2 and TiO2,indicating that siliceous rocks do not come from terrestrial sources and have a negative Ce anomaly.The Ce/Ce *value is 0.73 to 0.76,with an average value of 0.75,which is close to the characteristics of siliceous rocks in ocean basins;The LaN/CeN value ranges from 1.31 to 1.49,with an average of 1.38,which is close to the charac-teristics of siliceous rocks in open ocean basins.Based on comprehensive analysis,it is believed that the siliceous rocks were formed in a transitional environment from marginal seas to open oceans,suggesting that the Jinshajiang Ailaoshan tectonic belt developed in the Late Paleozoic in the Paleo Tethyan Ocean rather than in a backarc basin.关键词
哀牢山构造带南段/放射虫硅质岩/形成环境/哀牢山支洋Key words
southern Ailaoshan tectonic belt/radiolarian bedded chert/depositional environments/Ailaoshan branch分类
天文与地球科学引用本文复制引用
孙崇波,周洪兵,谢万洪,李敏同,杨洪伟..哀牢山构造带南段早泥盆世硅质岩形成环境及大地构造意义[J].西北地质,2025,58(5):140-150,11.基金项目
中国地质调查局项目"西南三江成矿带南段基础地质调查"(1212010880406、1212011120582)资助. （1212010880406、1212011120582）
