摘要
镇雄地区二叠系茅口组灰岩中部发育薄层状硅质岩夹层,本次工作对漆树湾及石场坝路线茅口组中部硅质岩夹层采取样品10件,并将样品磨制成薄片10片。对薄片进行镜下观察发现,硅质岩内普遍发育富液相气液两相流体包裹体。通过对所取10块硅质岩进行稀土元素分析测试,结果表明,稀土元素总量较低,LREE/HREE平均值范围为13.47～34.02;Ce/Ce~*平均值变化范围为0.29～0.51,为负异常;Eu/Eu~*平均值变化范围为1.19～1.31,为弱正异常。对比扬子地台南北缘二叠系层状硅质岩稀土元素特征发现,扬子地台西部镇雄地区层状硅质岩稀土元素地球化学特征与扬子南北缘层状硅质岩整体差异较大。但(La/Yb)_N,(La/Ce)_N等部分地球化学参数与扬子南缘相对接近,体现出二者具有一定的亲缘性。综合分析认为,镇雄地区二叠系茅口组硅质岩形成于受峨眉山玄武岩活动影响的陆表海环境背景,硅质岩以热水沉积成因为主。
10 samples of stratiform siliceous rocks in Permian Maokou Formation in Qishuwan and Shichangba area are collected.Microscopic observation shows that liquid-rich gas-liquid two-phase fluid inclusions occur in the siliceous rocks.Geochemical analysis shows that the rock has relatively low ΣREE,LREE/HREE values are 13.47~34.02 on average,Ce/Ce^* values are 0.29~0.51 on average with a negative anomaly;Eu/Eu^* values are 1.19~1.31 on average with a positive anomaly.The characteristics of rare earth elements of the Permian stratiform siliceous rocks in Zhenxiong area are quite different from those in the northern and southern margin of Yangtze platform.However,(La/Yb)_N value,(La/Ce)_N value and other partial geochemical parameters in Zhenxiong area is relatively close to that in the southern margin of Yangtze platform,indicating that there exists some affinity for these siliceous rocks.Comprehensive analysis considers that the Permian Maokou Formation stratiform siliceous rocks in Zhenxiong area are formed in the epicontinental marine environment which is affected by the basalt activity of Emeishan.The siliceous rocks are mainly formed by hot water deposition.
作者
让昊
吕俊
王亚伟
郭阳
曹竣锋
RANG Hao;LV Jun;WANG Yawei;GUO Yang;CAO Junfeng(Yunnan Geology & Mining International Mining Industry Co.,Lid, Kunming 650051,China;Chengdu Center,China Geological Survey,Chengdu 610081,China;Southwest of Geological Survey,Geological Survey Center for Non-ferrous Mineral Resources,Kunming University of Science and Technology, Kunming 650093,China)
出处
《矿物岩石》
CAS
CSCD
北大核心
2019年第1期36-42,共7页
Mineralogy and Petrology
基金
国家自然科学基金项目(41572060)
中国地质调查局(DD20160019)
关键词
硅质岩
稀土地球化学特征
沉积背景
镇雄
云南
siliceous rocks
REE geochemical characteristics
depositional setting
Zhenxiong
Yunnan
