古地理学报
古地理學報
고지이학보
JOURNAL OF PALAEOGEOGRAPHY
2015年
1期
21-32
,共12页
赵爱卫%谭秀成%李凌%罗冰%洪海涛%刘吉伟%王勇%段卓
趙愛衛%譚秀成%李凌%囉冰%洪海濤%劉吉偉%王勇%段卓
조애위%담수성%리릉%라빙%홍해도%류길위%왕용%단탁
四川盆地%寒武系%洗象池群%颗粒滩%古隆起
四川盆地%寒武繫%洗象池群%顆粒灘%古隆起
사천분지%한무계%세상지군%과립탄%고륭기
Sichuan Basin%Cambrian%Xixiangchi Group%grain bank%palaeo-uplift
通过对野外露头剖面、钻井以及1:200000区域地质调查等资料的综合研究,识别出四川盆地及其周缘地区寒武系洗象池群颗粒滩的岩石类型包括颗粒云岩、颗粒灰岩、细—中晶白云岩,颗粒类型主要为砂屑,次为鲕粒、砾屑以及少量生屑。发育潟湖—台内滩—潟湖、潟湖—台内滩—台坪、潮坪—潮缘滩—潮坪这3种向上变粗的沉积序列。单个旋回中的颗粒滩的厚度一般小于2.5, m,垂向上多表现为频繁叠置的小规模薄型滩体,且横向规模小、可对比性差。平面上,颗粒滩主要分布在古隆起区和水下相对高地,整体为东北向分布。海平面升降和沉积能量的高低控制着颗粒滩发育规模,而构造条件决定了颗粒滩的横向连续性和平面分布。
通過對野外露頭剖麵、鑽井以及1:200000區域地質調查等資料的綜閤研究,識彆齣四川盆地及其週緣地區寒武繫洗象池群顆粒灘的巖石類型包括顆粒雲巖、顆粒灰巖、細—中晶白雲巖,顆粒類型主要為砂屑,次為鮞粒、礫屑以及少量生屑。髮育潟湖—檯內灘—潟湖、潟湖—檯內灘—檯坪、潮坪—潮緣灘—潮坪這3種嚮上變粗的沉積序列。單箇鏇迴中的顆粒灘的厚度一般小于2.5, m,垂嚮上多錶現為頻繁疊置的小規模薄型灘體,且橫嚮規模小、可對比性差。平麵上,顆粒灘主要分佈在古隆起區和水下相對高地,整體為東北嚮分佈。海平麵升降和沉積能量的高低控製著顆粒灘髮育規模,而構造條件決定瞭顆粒灘的橫嚮連續性和平麵分佈。
통과대야외로두부면、찬정이급1:200000구역지질조사등자료적종합연구,식별출사천분지급기주연지구한무계세상지군과립탄적암석류형포괄과립운암、과립회암、세—중정백운암,과립류형주요위사설,차위이립、력설이급소량생설。발육석호—태내탄—석호、석호—태내탄—태평、조평—조연탄—조평저3충향상변조적침적서렬。단개선회중적과립탄적후도일반소우2.5, m,수향상다표현위빈번첩치적소규모박형탄체,차횡향규모소、가대비성차。평면상,과립탄주요분포재고륭기구화수하상대고지,정체위동북향분포。해평면승강화침적능량적고저공제착과립탄발육규모,이구조조건결정료과립탄적횡향련속성화평면분포。
Based on comprehensive research on field outcrops, wells and the regional survey in 1:200000 scale,the grain dolostone,grain limestone and fine- to mid-crystallized dolostone are found to constitute grain banks in the Cambrian Xixiangchi Group of Sichuan Basin and its adjacent areas.Sand-sized intraclast is the main type of intraclasts,and oolite,gravel-sized intraclast and minor bioclast follow in order.Three vertical sequences of upward-coarsening are identified,including lagoon-platform interior shoal-lagoon,lagoon-platform interior shoal-platform interior flat and tidal flat-tidal margin shoal-tidal flat.Each vertical cycle is commonly no more than 2. 5, m thick and thin banks are frequently superim-posed vertically in a relatively small scale,and the grain banks have small scale and bad continuity hori-zontally.The grain banks are mainly distributed on palaeo-uplifts and submarine highlands in the direction of northeast-southwest.Sea level fluctuation and sedimentary energy controlled the scale of grain banks, and the tectonic condition determined their lateral continuity and planar distribution.