【摘要】 <正> 一、引言本文所指的祁连山东南部,其地理范围是从西到东包括了甘肃的武威、古浪、天祝、永登,青海的亹源、大通、民和以及兰州以东地区,其地理方位约居东经101°20′—105°00′,北纬35°40′—38°00′(图1)。按地质学家习惯的命名,侏罗纪地层在兰州附近称为阿干更多还原

【Abstract】 The present paper deals with the Triassic to Jurassic stratigraphy of thesoutheastern Chilienshan in the region south of Wuwei and west of Lanchow ofthe Kansu Province. According to old stratigraphic determinaton, the TantungkouSeries to be Upper Triassic to lower Jurassic in age: the Yaochieh coal Series to.be Middle Jurassic or Middle lower Jurassic in age; the Hsiangtang Series to beUpper Jurassic or Jura-Cretaceous in age. The writer basing on field observations and paleontological studies of theabove mentioned stratigraphical section, proposed the following correlations:Supra formation--the Cretaceous Honkou Series ---- Unconformity----Upper Jurassic--the Hsiangtang Series ---- Disconformity----Middle Jurassic--the Hungkou Series---- Disconformity----Lower Jurasoic--the Yaochieh or Akanchen coal Series ----Disconformity----Upper Triassic--the Tantungkou or Nanyinger Series ----Unconformity----Sub-formation--the Paleozoic Nanshan Series. 1. The Upper Triassic Tantungkou Series. It is a transitional type of inter-mountainous-basin sediments, chiefly of dark green and purplish-red shales,micaceous sandstones, conglomeratic sandstones and conglomerates, having a discon-formable contact with the overlying lower Jurassic Yaochieh coal series and anunconformable relation with the underlying Paleozoic Nanshan Series. Thickness--384--800 m. Along the Tantungkou Valley near Yaochieh in the Yunteng districtplant fossils have been found in the darkgreen sandy shales as: Neocalamites sp.,Cladophlebis shensiensis Pan, Pterophyllum sp., etc. At Nanyinger, Wuwei, in thegrayish black shale plant fossils have been found as: Daeniopsis fecunda Halle,etc. The fossils have more or less close affinity with the flora of the UpperTriassic Yenchang Series of North Shensi, besides both their lithological charactersand stratigraphical relations are also similar, hence the Tantungkou Series can be correlated as of Upper Triassic in age. 2. The Lower Jurassic Yaochieh coal Series. According to the lithologicalcharacteristics, this Series can be subdivided into three divisions: the lower divisionbeing composed of grayish white conglomerate and sandstone with gray kaolinlayers as intercalations; the middle division being of petroliferous shale, andsandstone with coal seams, plant fossils formed as Coniopteris sp., Podozamiteslanceolatus Braun, Ctadophlebis sp., Hilssonia sp., Ginkgo sp., and Baiera sp.: theupper division being of oil-bearing shale, with kaolin and arenaceous intercala-tions, plant fossils found as Conipteris hymenophylloides Arongn., Elatoclatus sp,Baiera linaleyana Seward, Ginkgo sp., Sphenopteris sp., and Phoenicopsis sp., fishfossils as Ptycholepis sp., and Daphedina sp. Total thickness--164--398 m. 3. The Middle Triassic Hungkou Series. Chiefly composed of grayish green orgrayish black argillaceous beds intercalating with grayish white fine arenaceouslayers, containing ferrunginous concretions and thin coal seams. Thickness--28--108 m. Plant fossil found as Coniopteris hymenophylloides Brongn, Gekanowskia sp.,Neocalamites sp., Baiera sp., Ginkgo sp. and Equisetites sp. This series is bothdisconformably related with the underlying lower Jurassic Yaochieh coal Series andthe overlying upper Jurassic Hsiangtang Series, and may be correlated with theChiklo Series of North Shensi, the Yungkang Series of Shansi and the Tapou Seriesof Liaoning. 4. The Upper Jurassic Hsiangtang Series. Lithologically it can be subdividedinto three formations. The upper formation is of purplish red argillaceous bedswith sandstone and conglomeratic sandstone intercalations: the middle formationof purplish sandstone and kaolin intercalations: the lower formation of purplishred, grayish green kaolin beds, dark green breccia and sandstone. Thickness----67--1000 m±. This Series contains some vertebrate fossils as Sunchurous MiaoiYoung.更多还原