摘要
法国布·玛和西班牙拉·弗矿床分别产于富含干酪根的白云岩和沥青的铁质白云岩中。正构烷、烷基环已烷、藿烷和甾烷等生物标志化合物研究揭示了成矿时发生过细菌活动。细菌在沉积－成岩早期发育于还原水体中，或在成岩期－成岩期后由大气降水自地表带来，其赖以生存的有机质既可以是生物聚合体（布·玛矿床），亦可以是地质聚合体（拉·弗矿床）。这些微生物在１００℃以下的温度条件下生存繁殖，使硫酸盐还原生成硫化氢。
The Bois madame sulphidic Zn Pb mineralization in Gard, France, occurs in Kimmeridgian dolomite in the immediate vicinity of layers rich in organic matter of planktonic origin. The La Florida Zn Pb deposit in Santander, Spain, is hosted by Aptian ferroan dolomite, which is usually very poor in organic matter except bitumens impregnations. Studies of organic geochemistry show that the organic matter in Bois madame deposit is autochthonous marine kerogen. There is no effect of thermal phenomena (hydrothermalism) of notable intensity. The bitumens in the La Florida deposit exhibit allochthonous compositional character with origin of migration.A slight increase of T max values with increasing proximity to mineralization reveals the existence of a low temperature thermal event, very likely related to ore genesis. The Two deposits are both rich in alkylcyclohexanes, the C 31 and the C 35 of the hopane series and the n alkanes with medium molecular weight showing a secondary distribution with an even number of carbon atoms. In La Florida, the elimination of the n alkanes and the relative increase of the unresolved complex mixture reveal that their alteration resulted from biodegradation. These results indicate the presence of the activity of the sulphato reducing bacteria in both ore deposits. The bacteria were either developed in reducing water or in sediment during sedimentation early diagenesis brought by meteoric water from paloesurface during diagenesis. They lived at the expense of the biopolymer (e.g. in Bois Madame deposit) as well as of the geopolymer (e.g. in La Florida deposit) in an environment below 100 ℃. These sulphato reducing bacteria reduced sulfate to the hyrdrogen sulphide, which resulted in the precipitation of lead zinc sulphide.
出处
《矿床地质》
CAS
CSCD
北大核心
1997年第1期61-70,共10页
Mineral Deposits
基金
法国政府博士学位奖学金资助
关键词
碳酸盐岩
铅锌矿床
细菌活动
成矿作用
carbonate rock, lead zinc deposit,bacterial activity,biomineralization,Europe
