【摘要】 <正> 贵州中三叠世拉丁尼克期古地理分异明显其西北侧属浅海台地,东南侧为开阔海盆(图1)。盆地相沉积称江洞沟组,是一套砂泥岩组合类复理石沉积,厚逾数千米,在贞丰联合厚达3000余米,尚未见顶。笔者在1975年调查中三叠世生物礁相沉积时,发现兴义泥凼、册亨、边阳等地的江洞沟组具有明显韵律层,底面印模发育,更多还原

【Abstract】 Sanchahe area,Luodian County,Guizhou Province,was in the northern margin of Guizhou-Guangxi Sea Basin and to the south of the Bangen atollduring Ladinic stage.A series of beautiful turbidites with distinct rhythm wasdeposited there,containing small amount of ammonites,Pelecypoda and otherorganic clastics.These sediments are now described as the Jiangdonggou Forma- tion,which have following characteristics:1.The rhythmic bedding is quite distinct and the Bouma cycle can be clearlydistinguished with B,C,D,and E intervals being hingly developed.Among otherthings,the D-E and B-E sequences are more common.2.Various kinds of underside casts,such as flute casts,groove casts andload casts were developed there.The paleocurrent direction can be determined bythe flute or groove casts ranging 268-297°.3.Major component of these sediments is feldspar,and then quartz.Theargillaceous material occupies 3-35%,while the calcite matrix （cement） is1.5-30%.Therefore,the sediments belong in feldsparthic sandstone.The round-ness of particles is poor and grain size are usually more than 4φ.4.As for parameters of grain-size,the average diameter （Mz） of particles isof 4.073φ,belonging to silt size;the standard deviation （σ₁） is of 0.738,indica-ting middle degree of sorting;the mean skewness （SK_I） is of -0.0002,expressingapproximate symmetry;the average value of kurtosis （Kg） is 0.9369,showingapproximately normal distribution;the average discriminant score （Y） of envi-ronment （river or turbidity flow） is of 7.6725,representing turbidity current.5.In aspect of graphic feature,straight line and simple brokenline arereproduced on probability diagram of grain size with low slope ranging from32° to 64°,suggesting mainly a graded suspension transport,but a small amountof saltation transport may have taken place.CM diagram shows parallel C=Mspacing.According to sedimentary sequence,underside casts,grain-size and graphicfeature,it is Presumed that the Jiangdonggou Formation was the distal faciesof turbidity current far from its provenance.更多还原