摘要
索尔碎屑岩出露于西藏中部索尔—戈昂错一带,角度不整合覆盖于果芒错蛇绿混杂岩中的地幔橄榄岩之上,粗碎屑岩层和细碎屑岩层互层产出,并见有角砾状灰岩夹层。索尔碎屑岩中粗碎屑岩主要由灰黑色碎屑和土黄色基质所组成;细碎屑岩呈灰黑色,块状构造。碎屑的主体成分为蛇纹岩,并含有少量的尖晶石和斜长石,基质为泥晶结构碳酸盐。碎屑主要呈棱角状—次圆状,边界平直,可能是构造破碎后快速堆积而形成的。在蛇纹岩碎屑边部普遍可见垂直边界生长的板状或粒状方解石,部分碎屑之中方解石呈逐步向内部生长的趋势,而在少量的岩石中已形成了交代残余结构,反映索尔碎屑岩中的碎屑受到了碳酸盐不同程度的交代作用。通过与Gebel Mohagara蛇绿质碳酸盐岩和West Magnitogorsk古岛弧中出露的蛇绿质碳酸盐岩对比研究,初步认为索尔碎屑岩是地幔橄榄岩发生破碎后受到碳酸盐热液流体的交代所形成的。
Suoer clastic rocks are located in Souer-Geangco,central Tibet,covering the mantle peridotite of Guomangco ophiolitic melange in angular unconformity.Coarse and fine grained Suoer clastic rocks were interbeded,associated with brecciated limestone interlager.Coarse grained Suoer clastic rocks are mainly composed of grey black clastic and earthy yellow groundmass.Fine grained clastic rocks are black in color with massive structure.The clastic rocks include serpentinite and minor spinal and plagioclase,and the groundmass is consisted of micritic carbonate.The clastic rocks possess angular and subrounded shape,with fiat and straight edges,suggesting the origin of rapid accumulation after tectonic breaking.In serpentinite clastic,platy and grained calcites are commonly vertical to the edges,and some calcites gradually grow inside the calstic,and moreover,the replacement remnant textures are observed in minor calstic rocks,indicating various replacement of carbonate.Based on petrologic char acteristics and contrasting with the ophicarbonate in Gebel Mohagara and West Magnitogorsk ancient arc,the origin of Suoer clastic rocks are considered as mantle peridotites break and peridotite calstics were metasomated by hydrothermal fluid of carbonate.
出处
《世界地质》
CAS
CSCD
2014年第2期330-336,共7页
World Geology
基金
中国自然科学基金(41272240)
中国地质调查局项目(1212011121248)联合资助
