摘要
黑色岩系在其形成和发展中,特别是在成岩成矿过程中都离不开生物地球化学作用。通过对震旦纪一下古生代五套黑色岩系及其中四类矿床的矿物、岩石、地球化学及稳定同位素研究,从生物成矿的角度讨论了这些黑色岩系和矿床在成岩成矿过程中的生物地球化学作用,并强调生物地球化学元素循环及生物地球化学体系研究的重要性。
Based on mineralogic, petrologic, geochemical and stable isotopic studies on Sinian to Early Paleozoic black shale series and related four types of ore deposits, the authors discussed biogeochemical features during diagenetic and metallogenetic processes from point of view of biomineralization. An emphasis was also put on the studies on biogeochemical cycling of ore-forming elements and on biogeochemical systems. The major conclusions are summarized as follows.
(1) A noticeable feature of the black shale series is its close relation with organism activities and with cycling of biogeochemical elements (C, N, P, S, O, Fe, Mn, Mo, V, Zn, Si, etc.) not only during the deposition, diagenesis, and mieralization of the black shale series, but also during the primary and secondary biogeochemical processes.
(2) Forming and preserving conditions of sulfides (Fe, Ni, Mo, Au, Ag) in type Ⅰ deposits as well as stone coal are similar to that of the black shale series. Their syngenesis and diagenesis were occurred under euxinic condition,in which cycling of boigeochemical elements and activities of microorganisms were mostly obvious.
(3)There are some differences on the forming and preserving conditions between type Ⅱ deposits manganese carbonate and the black shale series. The euxinic marine environment was favorable for manganese storage in water column before its precipitation. Micro-organisms played an important role in the formation and re-enrichment of manganese.
(4) Type Ⅲ deposits barite and witherite have very close genetic relation with black chert formation. In modern oceans most of the chert formation are biogenetic. Carbon isotope study shows that micro-organism took active part in the re-enriching processes of barite and witherite during diagenesis.
(5) Type Ⅳ deposits are carbonate hosted Pb, Zn, and Hg deposits, which are of some genetic linkage with such hosting rocks. The high concentration of Pb, Zn, and Hg in modern marine flora, the identification of existence of methyl mercury and lead, as well as the high concentration of Hg in modern flora and fauna and in fossils occurred in unmineralized rocks in the Wanshan Hg ore deposite all prove that theprimary biogeochemical processes provided essential source for such ore deposits.
(6) The black Shale series is a time-specific sedimentary facies with unique repeatability through all geological evolution. Therefore, a great attention must be paid to the study of biogeochemical cycling of elements, relating to the for mation of ore deposits, and biogeochemical system, e.g. the study of interacting evolution of biosphere, atmosphere, hydrosphere and lithosphere.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1991年第2期65-72,T002,共9页
Acta Petrologica Sinica
关键词
黑色岩系
成矿
成岩
生物地球化学
Black shale series
Diagenetic and metallogenetic processes
Biogeochemical process
Biogeochemical systems
