【摘要】："皮殼—葡萄狀"白云巖是一種非常特殊結構的白云巖。文中報道了塔里木盆地西北緣東二溝及塔北星火101井上震旦統奇格布拉克組中皮殼—葡萄狀白云巖特征,并對其成因進行了探討。皮殼狀—葡萄狀白云石中發(fā)育明、暗纖狀白云石或紋層條帶的含少量細晶的纖狀—細粒狀白云石以及腎狀和葡萄狀粉細晶白云石;由球形、桿形、孢子形等藍細菌構成泡沫狀結構;明暗、環(huán)帶狀橙紅色光或中等橙紅色光、核部發(fā)光較暗或不發(fā)光;與基質白云石相比,葡萄—皮殼狀白云石δ~(13)C_(PDB)相似;但δ~(18)O_(PDB)正偏,87Sr/86Sr相對高(0.70887~0.70939)、但與震旦紀海水(0.7087~0.7094)相似,從皮殼邊緣、暗色(藍細菌)至核部,微區(qū)δ~(18)O_(PDB)、δ~(13)C_(PDB)顯示了環(huán)帶內變化較小、環(huán)帶外的強烈負漂移;云化程度的增加,δ~(18)O_(PDB)、δ~(13)C_(PDB)負偏明顯,~(87)Sr/~(86)Sr增加。皮殼—葡萄狀白云巖中Al_2O_3、Fe_2O_3、MnO、LREE/HREE值均低于基質泥粉晶云巖對應值、稀土總量介于基質與粉細晶云巖之間,而Na_2O+K_2O、P_2O_5、Sr、Hg、Cu、Sr/Ba、Sr/Mn、δCe值均高于基質泥粉晶云巖對應值;且隨著云化程度的提高,總體呈現出Mn含量增加,Al_2O_3、Fe_2O_3、Na_2O+K_2O、P_2O_5、Sr/Ba、Fe/Mn等值遞減的趨勢;由此判斷皮殼狀—葡萄狀白云石可能是弱還原、保存較好的海水中形成,或在成巖早期或淺埋藏孔隙海水為主的流體中形成、部分經歷了較強的大氣水作用改造。
[Abstract]:Crust-grape dolomite is a very special structure of dolomite. In this paper, the characteristics of crust-grape dolomite in the Sigebrak formation of the Sinian formation in the Dongergou and Tabei Xinghuo 101 wells in the northwest margin of the Tarim Basin are reported, and the genesis of the dolomite is discussed. In shell-grape dolomite, there are a small amount of fine-grain fine-fine dolomite and kidney-shaped and grape-shaped fine-grain dolomite, which is composed of spherical, rod-shaped, spore-shaped and other blue bacteria, and dark, annular orange-red light or medium orange-red light, and the nucleus is dark or not luminous. Compared with the matrix dolomite, grape-shell dolomite 未 ~ (13) C _ (PDB) is similar. However, 未 ~ (18) O _ (PDB) is positive, 87Sr/86Sr is relatively high (0.70887 鈮，

本文編號：2502186