摘要
金沙江板块缝合带戛金雪山地区的灰岩块体具有以下特点:(1)在整条缝合带上,灰岩块体集中分布于戛金雪山地区;(2)灰岩块体形态奇特,没有明显的优选方位,块体内与围岩的构造变形截然不同;(3)自下而上的地层序列是火山岩系-火山碎屑灰岩-生物碎屑灰岩;(4)由岩石化学成分判别的结果表明,灰岩块体之下的火山岩为洋岛火山岩。据此认为,戛金雪山地区的灰岩块体井非混杂堆积中的外来岩块,而是随洋壳俯冲而拼贴于消减带上的洋岛碳酸盐岩。
Limestone blocks in Gajinxueshan area of the Jinshajiang plate suture zone are characterized by:(1)concentrated distribution in Gajinxueshan area;(2)block deformation (strange in shape with no preferred orientation)being quite different from that of the surrounding rocks;(3) special stratigraphic sequence (from bottom upwards): volcanic rocks, pyroclastic limestone and bioclastic limestone ;and(4) that the volcanic rocks mentioned above are ocean-island basalt (OIB). All the above features show that the limestone blocks in Gajinxueshan area are far from exotic blocks of melange accumulation, but ocean-island carbonate rocks matched in the plate suture zone along with the oceanic crust during consumption of the ocean-bearing plate.
出处
《华南地质与矿产》
CAS
1998年第1期20-25,共6页
Geology and Mineral Resources of South China
基金
地矿部攻关项目(95-02-001-03)和地矿部区调专项(地科专96-30)联合资助
关键词
金沙江板块缝合带
灰岩块体
洋岛序列
火山岩
成因
构造环境
Jinshajiang suture zone limestone blocks stratigraphic sequence ocean-is-land volcanic rocks Gajinxueshan area
