Origin of botryoidal dolostone of the Sinian Dengying Formationin Sichuan Basin
Zhang Jie1,2, Brian Jones3, Pan Liyin1,,2, Zhou Jin′gao1, Qin Yujuan1,2, Hao Yi1, Wu Mingde4
1 PetroChina Hangzhou Research Institute of Geology,Hangzhou.310023,Zhejiang 2 Key Laboratory of Carbonate Reservoir,CNPC,Hangzhou.310023,Zhejiang 3 Department of Earth and Atmospheric Sciences,University of Alberta,Edmonton,Alberta T6G 2E3,Canada 4 Qinghai Exploration Bureau of Environment Geology,Xining.810007,Qinghai
Abstract Sinian Dengying Formation (up to 1000m) in Sichuan Basin is composed of fine crystalline dolostones. In some parts of the formation(mainly in Members 2 and 4) distributed various shaped botyroidal masses of dolomite,up to 75cm long in maximum. They are either parallel to bedding or cutting across bedding. Those cross sections reveal that isopachous bands of various types of dolomite are developed as cements. Large amount of irregular shaped cavities are still present in the central parts of some larger bodies, which formed as a result of subterranean dissolution that was associated with karst development. The surrounding micritic dolostone was originally deposited from seawater protocrystallization, and the subsequent cements can be divided into four stages:(1)the dolomitized automicrite in some samples was the 1st stage cement,which formed close to the surrounding micritic dolostone due to various physiochemical and possible biological influences;(2)the 2nd stage fibrous dolomite had an absolute ordering crystal structure and nearly ideal crystal cell parameter,which may have originated from marine waters and adjusted to be ordered during the late diagenesis;(3)the 3rd stage fine- to medium-crystal dolomite including residual of fibrous dolomite crystals dissolved in a near-surface meteoric environment after tectonic uplift;(4)the 4th stage medium-coarse crystal dolomite primarily precipitated under a burial environment and partially filled the central parts of the cavities, with some unfilled cavities. It is apparent that the Dengying Formation was subject to multiple phases of diagenesis including karst development,precipitation of various cements,and multiple episodes of dolomitization. Except the paleokarstification,all of the other processes critically reduced the porosity of the petroleum reservoir that developed in the Dengying Formation. The paleokarstification which related to botryoidal dolostone has crucial importance to the Dengying Formation reservoir. The study of botryoidal dolostone in Sinian Dengying Formation conduces to understand the reservoir origin and evolution of the Dengying Formation dolostone,and guide the Precambrian petroleum development of Sichuan Basin
About author: Zhang Jie,born in 1983,is a geologist with a master degree in Hangzhou Research Institute of Geology. He is engaged in research of carbonate reservoir. Address:Hangzhou Research Institute of Geology,Xixi Road 920,Xihu District,Hangzhou,Zhejiang Province,310023; E-mail:zhangj_hz@petrochina.com.cn.
Cite this article:
. Origin of botryoidal dolostone of the Sinian Dengying Formationin Sichuan Basin[J]. JOPC, 2014, 16(5): 715-725.
. Origin of botryoidal dolostone of the Sinian Dengying Formationin Sichuan Basin[J]. JOPC, 2014, 16(5): 715-725.
曹仁关. 2002. 川滇震旦系灯影组葡萄石的沉积环境[J]. 云南地质,21(2):208-213. 陈明,许效松,万方,等. 2002. 上扬子台地晚震旦世灯影组中葡萄状—雪花状白云岩的成因意义[J]. 矿物岩石,22(4):33-37. 洪海涛,谢继容,吴国平,等. 2011. 四川盆地震旦系天然气勘探潜力分析[J]. 地质与勘探,31(11):1-5. 雷怀彦,朱莲芳. 1992. 四川盆地震旦系白云岩成因研究[J]. 沉积学报,10(2):69-78. 刘集银,王自友. 1988. 白云石的晶体结构特征和X-射线研究[J]. 矿物岩石,8(1):28-33. 刘鸿允,等. 1991. 中国震旦系[M]. 北京:科学出版社,1-388. 刘怀仁,刘明星,胡登新,等. 1991. 川西南上震旦统灯影组沉积期的暴露标志及其意义[J]. 岩相古地理,(5):1-10. 罗跃平. 2005. 一种少见的宝石:葡萄石[J]. 宝石和宝石学杂志,(2):36. 梅冥相. 2012. 从3个科学理念简论沉积学中的“白云岩问题”问题[J]. 古地理学报,14(1):1-12. 彭志忠,周公度,唐有琪. 1957. 葡萄石的晶体结构[J]. 科学通报,2(11):330. 施泽进,梁平,王勇,等. 2011. 川东南地区灯影组葡萄石地球化学特征及成因分析[J]. 岩石学报,27(8):2263-2271. 王东,王国芝. 2010. 四川南江灯影组白云岩葡萄状构造成因分析[J]. 四川地质学报,30(4):454-456. 向芳,陈洪德,张锦泉. 1998. 资阳地区震旦系灯影组白云岩中葡萄花边的成因研究[J]. 矿物岩石,18(增):136-138. 张杰,寿建峰,张天付,等. 2014. 白云石成因研究新方法: 白云石晶体结构分析[J]. 沉积学报,32(3):550-559. 张荫本. 1980. 震旦纪白云岩中的葡萄状构造成因初探[J]. 石油实验地质,(4):40-43. 赵文俞,王勤燕,孙振亚,等. 1999. 葡萄石微结构的TEM研究[J]. 电子显微学报,18(5):548-553. Hood A S, Wallace M W, Drysdale R N. 2011. Neoproterozoic aragonite-dolomite seas？Widespread marine dolomite precipitation in Cryogenian reef complexes[J]. Geology,39(9):871-874. Clayton R N,Degens E T. 1959. Use of carbon isotope analyses of carbonates for differentiating fresh-water and marine sediments[J]. AAPG Bulletin,4:889-897. Halverson G P,Duds F ,Maloof A C, et al. 2007. Evolution of the 87Sr/86Sr composition of Neoproterozoic seawater[J]. Palaeongeography,Palaeoclimatology,Palaeoecology,256(3-4):103-129. Harris P M. 2010. Delineating and quantifying depositional facies patterns in carbonate reservoirs:Insight from modern analogs[J]. AAPG Bulletin,94(1):61-86. Harris P M,Ellis J. 2009. Satellite imagery,visualization,and geological interpretation of the exumas,Great Bahama Bank: An analog for carbonate sand reservoirs[R/CD]. SEPM Short Course Notes,53:1-49 and 2 DVDs. Keith M L,Weber J N. 1964. Carbon and oxygen isotopic composition of selected limestones and fossils[J]. Geochimica et Cosmochimica Acta,28:1786-1816. Sibley D F. 1991. Secular changes in the amount and texture of dolomite[J]. Geology,19:151-154.
