地学前缘 ›› 2013, Vol. 20 ›› Issue (1): 107-116.

• 论文 • 上一篇    下一篇

四川盆地东南缘河坝MVT铅锌矿与古油气藏的成生关系

王国芝,刘树根,陈翠华,王东,孙玮   

  1. 1. 成都理工大学 油气藏地质及开发工程国家重点实验室, 四川 成都 610059
    2. 成都理工大学 地球科学学院, 四川 成都 610059
    3. 中国石化西南油气分公司 勘探开发研究院海相所, 贵州 贵阳 550004
  • 收稿日期:2012-05-18 修回日期:2012-07-06 出版日期:2013-01-15 发布日期:2013-01-15
  • 作者简介:王国芝(1964—)，男，教授，主要从事水岩作用和流体地球化学研究。 E-mail:wangguozhi66@163.com
  • 基金资助:

    国家自然科学基金项目(41273060，41072082)；国家重点基础研究发展计划“973”项目(2012CB214805)

The genetic relationship between MVT Pb-Zn deposits and paleooil/gas reservoirs at Heba, Southeastern Sichuan Basin.

 WANG  Guo-Zhi, LIU  Shu-Gen, CHEN  Cui-Hua, WANG  Dong, SUN  Wei   

  1. 1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China
    2. School of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China
    3. Marine Facies Academy of Exploration & Development Research Institute, Southwest Branch Company, Sinopec, Guiyang 550004, China
  • Received:2012-05-18 Revised:2012-07-06 Online:2013-01-15 Published:2013-01-15

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摘要：

MVT铅锌矿与(古)油气藏在空间上的密切共生/伴生关系，说明成矿与成藏具有密切的成因联系。四川盆地东南缘的河坝铅锌矿产于震旦系灯影组古油气藏中，虽然二者在空间上密切共生，但铅锌矿的规模远较古油气藏的规模小。形成铅锌矿的流体具有较高的盐度(w(NaCl)=21.33%~23.83%)并富含有机质，成矿流体的峰温为122~134 ℃。与闪锌矿共生萤石的RbSr和SmNd同位素年龄显示成矿发生于128~130 Ma。研究区的古油气藏先后经历了多期成藏与破坏。奥陶纪—中志留世时期第一次成藏，加里东期末被破坏；二叠纪—中三叠世时期二次生烃形成油藏，晚三叠世—侏罗纪时期随着埋藏深度增加，石油发生热裂解形成古气藏，燕山期古气藏被破坏。铅锌矿的成矿仅与石油的热裂解和古气藏的破坏密切相关。石油热裂解形成硫化氢，热裂解过程中的超压使硫化氢溶于水为铅锌矿成矿提供硫源，构造隆升造成古气藏破坏，含硫化氢的油田卤水与成矿流体混合成矿。

关键词: MVT铅锌矿, 油气藏, 成矿成藏耦合, 灯影组

Abstract:

Abstract: The intimate coexistence of MVT PbZn deposits with oilgas reservoir suggests a genetic linkage between mineralization and hydrocarbon accumulation. The PbZn deposit from Heba in southeastern Sichuan Basin occurred in the paleogas reservoir in Dengying Formation, and its distribution area of PbZn deposit is much smaller than that of paleogas reservoir although both of them coexisted intimately. The mineralization fluid of PbZn deposit is characterized by high salinity(21.33%23.83% NaCl) and enrichment of organic matter, and its homogeneous temperature concentrated in 122134 ℃. The ages of RbSr and SmNd of fluorite coexisting with sphalerite suggest that the mineralization took place in 128130 Ma. Multiphase accumulation and destruction of hydrocarbon can be recognized in this paleooil/gas reservoir. The first hydrocarbon accumulation and destruction took place in the OrdovicianMiddle Silurian and the end of the Silurian, respectively. The second accumulation of hydrocarbon took place during the Permian and the middle Triassic, the oil began thermal cracking and formed gas reservoir as the burial depth of oil reservoir increased during the late Triassic and Jurassic; the paleogas reservoir was destroyed during the Yanshanian. The thermal cracking of oil and destruction of paleogas reservoir are responsible for mineralization of PbZn deposit. The thermal cracking of oil produced some H2S and the super pressure resulting from thermal cracking had the H2S dissolved in the water to supply sulphur for mineralization of PbZn deposit;tectonic uplift resulted in the destruction of the paleogas reservoir, and the brine with H2S lying under the paleogas reservoir migrated up and mixed with mineralization fluid leading to the formation of PbZn deposit.

Key words: MVT Pb-Zn deposit, oilgas reservoir, coupling of mineralization and accumulation, DengyingFormation

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