古地理学报
古地理學報
고지이학보
JOURNAL OF PALAEOGEOGRAPHY
2015年
3期
347-357
,共11页
金民东%谭秀成%李凌%曾伟%连承波%罗冰%山述娇%周涛
金民東%譚秀成%李凌%曾偉%連承波%囉冰%山述嬌%週濤
금민동%담수성%리릉%증위%련승파%라빙%산술교%주도
颗粒滩%海平面%古地貌%龙王庙组%四川盆地
顆粒灘%海平麵%古地貌%龍王廟組%四川盆地
과립탄%해평면%고지모%룡왕묘조%사천분지
grain bank%sea level%palaeogeomorphology%Longwangmiao Formation%Sichuan Ba-sin
以四川盆地磨溪—高石梯地区下寒武统龙王庙组颗粒滩为研究对象,结合钻井、测录井、岩心和薄片等资料,对龙王庙组颗粒滩特征、分布规律和主控因素进行了综合分析。研究区内颗粒滩岩石类型主要有两类:一类为具有明显颗粒结构的颗粒云岩,以砂屑云岩或鲕粒云岩为主;另一类为具有残余颗粒结构的晶粒云岩。颗粒滩主要发育向上变浅、粒度变粗的沉积序列,垂向上,与下部细粒沉积物可构成滩间海—颗粒滩、局限湖—颗粒滩等沉积相序;横向上,颗粒滩连续性较好,具有大面积连片分布的特征,自西北—东南向发育程度呈逐渐增大的趋势。进一步分析后认为,海平面的相对变化和沉积水体能量高低决定了龙王庙组颗粒滩的发育特征和叠置样式,不同级次海平面的升降变化使颗粒滩发育层位和发育程度得以定型,而沉积时期的古地貌则最终决定了龙王庙组颗粒滩平面分布的差异性。
以四川盆地磨溪—高石梯地區下寒武統龍王廟組顆粒灘為研究對象,結閤鑽井、測錄井、巖心和薄片等資料,對龍王廟組顆粒灘特徵、分佈規律和主控因素進行瞭綜閤分析。研究區內顆粒灘巖石類型主要有兩類:一類為具有明顯顆粒結構的顆粒雲巖,以砂屑雲巖或鮞粒雲巖為主;另一類為具有殘餘顆粒結構的晶粒雲巖。顆粒灘主要髮育嚮上變淺、粒度變粗的沉積序列,垂嚮上,與下部細粒沉積物可構成灘間海—顆粒灘、跼限湖—顆粒灘等沉積相序;橫嚮上,顆粒灘連續性較好,具有大麵積連片分佈的特徵,自西北—東南嚮髮育程度呈逐漸增大的趨勢。進一步分析後認為,海平麵的相對變化和沉積水體能量高低決定瞭龍王廟組顆粒灘的髮育特徵和疊置樣式,不同級次海平麵的升降變化使顆粒灘髮育層位和髮育程度得以定型,而沉積時期的古地貌則最終決定瞭龍王廟組顆粒灘平麵分佈的差異性。
이사천분지마계—고석제지구하한무통룡왕묘조과립탄위연구대상,결합찬정、측록정、암심화박편등자료,대룡왕묘조과립탄특정、분포규률화주공인소진행료종합분석。연구구내과립탄암석류형주요유량류:일류위구유명현과립결구적과립운암,이사설운암혹이립운암위주;령일류위구유잔여과립결구적정립운암。과립탄주요발육향상변천、립도변조적침적서렬,수향상,여하부세립침적물가구성탄간해—과립탄、국한호—과립탄등침적상서;횡향상,과립탄련속성교호,구유대면적련편분포적특정,자서북—동남향발육정도정축점증대적추세。진일보분석후인위,해평면적상대변화화침적수체능량고저결정료룡왕묘조과립탄적발육특정화첩치양식,불동급차해평면적승강변화사과립탄발육층위화발육정도득이정형,이침적시기적고지모칙최종결정료룡왕묘조과립탄평면분포적차이성。
In this paper,the authors focused on grain bank of the Lower Cambrian Longwangmiao Formation in Moxi-Gaoshiti area,Sichuan Basin.Combined with abundant materials,such as drilling and logging data,cores and thin sections,the characteristics,distribution and its major controlling factors of grain bank in the Longwangmiao Formation were synthetically analyzed.There are two main rock types of grain bank in research area,one is grain dolostone with obvious granular structure,which is dominated by dolarenite and oolite dolostone,and the other is crystal grain dolostone with residual granular structure. Grain bank mainly has upward shallowing and granularity coarsening sequences,and could constitute sedi-mentary sequences of interact bank sea -grain bank and restricted lagoon -grain bank with lower fine-grained sediment in the vertical direction.In the lateral direction,grain bank has good continuity and is characterized by continuous distribution in a large area.On the plane,the development degree of grain bank increases gradually from northwest to southeast.Further analysis shows that the development charac-teristics and superimposed pattern of grain bank in the Longwangmiao Formation were determined by the relative sea-level change and sedimentary energy variation,the development horizon and degree of grain bank were formed by different grades of sea level fluctuation,and the palaeogeomorphology finally deter-mined the difference of planar distribution of grain bank during the depositional period of Longwangmiao Formation.