石油与天然气地质 ›› 1986, Vol. 7 ›› Issue (3): 207-217.doi: 10.11743/ogg19860302

• 论文 • 上一篇    下一篇

黔、桂中三叠世浊流沉积的形成环境

贺自爱   

  1. 地质矿产部石油地质综合大队
  • 收稿日期:1985-11-21 修回日期:1986-02-28 出版日期:1986-09-25 发布日期:2012-01-16

FORMATION ENVIRONMENT OF TURBIDITY CURRENT DEPOSITS IN THE MIDDLE TRIASSIC OF GUIZHOU AND GUANGXI

He Ziai   

  1. Comprehensive Research Institute of Petroleum Geology, Ministry of Geology and Mineral Resources
  • Received:1985-11-21 Revised:1986-02-28 Online:1986-09-25 Published:2012-01-16

PDF (PC)

387

被引次数

29

摘要：

黔、桂中三叠世浊流沉积的物源非西非东,而是来自桂东南岛弧,根据在于:(1)浊积岩的时代由东南向西北渐次变新;(2)东南发育近源相,西北发育远源相;(3)桂东南火山岩发育,近火山口特征明显,而桂西北却只有较薄的夹层,远火山口特征显著;(4)近源槽模 NNE 向,远源近于东西;(5)槽模规模由东南向西北明显变小。浊积岩石英含量43—59%,SiO 70.46—72.04,K2O/Na2O<1,正属于 Crook(1974)所划分的中等石英含量杂砂岩范畴,作为安第斯型大陆边缘海沟型的代表。其实,此一区间范围较广,应进一步细分,含量偏低者与洋壳关系密切,应属海沟型;偏高者与陆壳关系亲近,应属弧后盆地型。此区浊流沉积正属后者而非前者。广布70000km2,厚达3000—5000m 的浊流沉积,北为边缘礁堤所限,南受火山岛弧所控,沉积物中既有中、酸性岩浆岩的踪迹,又有微型扩张地幔上溢的基性、超基性侵入岩体,正是弧后盆地的沉积特征。

Abstract:

Turbidity current deposits developed widely in Guizhou and Guangxi du-ring the Middle Triassic.Terrigenous materials came from island are in thesoutheast part of Guangxi,this is based on that:1.The turbidites in the southeast occured anterior to that in the northwest;2.The proximal facies in the southeast changes into distal facies in the northwest;3.Volcanic rocks decreasein thickness and even pinch out from southeast to northwest;4.The flow direc-tion of the flute castes point to NNE but not point to EW in the proximal facies;5.The scale of the flute castes changes gradually small from southeast to northwest.The quartz contentes are from 43 to 59%,SiO2 ranges from 70.46 to 72.04%,ratio of K2O to Na2O is less than 1 in the turbidite rocks,which isin accord with graywack of middle quartz content classified by Crook(1974),but it is in the range of high value.This shows that their formation condition maybe distent with oceanic crust but close to continental crust.In addition,the tur-bidity current deposits,ranging from 3000 to 5000 m in thickness throughout the study area,distributed extensively about 70000km2 in Guizhou,Guangxi and Yunnan,which are bounded by a marginal reef barrier in the north and avolcanic island arc in the south.It is shown that such sediments were formed in back-arc basin but not fore-arc trench.It is because the turbidites belong to back-arc basin that the sediments con-tain intercalated beds of volcanic rocks.More over,the closer to the islandarc,the greater the thickness.Since the continental crust of the back-arc basin changed thinner under the micro-spreading processes,mantle materials thus spil-led over to develop into basic,untrabasic intrusive bodies and slump conglo-merats that are resulted by faults.