天津蓟县剖面中元古界铁岭组叠层石岩礁中海绿石的产出特征及地质意义

Geological Characteristics and Significance of Glauconites in Stromatolite Rock-Reef of Mesoproterozoic Tieling Formation in Jixian County

海绿石作为一种特殊的指相矿物,长期以来受到地质学家的重视与研究。显生宙的海绿石,多年来研究的结果表明海绿石发育在慢速弱还原环境。而天津蓟县中元古界铁岭组叠层石岩礁中的海绿石,处于铁岭组二段的早期高水位体系域(EHST)中,以薄膜状形式产在叠层石柱体与柱体间泥晶的交界处,可能指示了一种特殊的海底胶结作用。独特的产出特征表明了前寒武纪(约1000Ma左右)的正常高能浅海环境似乎还处于一种氧气不充分的环境。

Gglauconite, as a special indicative-facies mineral, has interested geologists for some time. The Phanerozoic glauconites in this study show that they were formed in an environment of weak reduction and low sedimentation. However, the glauconites in stromatolite rock-reef of the Mesoproterozoic Tieling formation in the Jixian county were formed in a form of film at the contact between stromatolite pillars and situated in a early high standard system tract (EHST) of the second member of the Tieling formation. This may imply a special benthal cementation and a normal, shallow marine environment, may be an insufficient oxygen environment, in the Precambrian (about 100 Ma ).