The Characteristics And Correlation Between Tongbomiao-Nantun Formation In Hailaer Basin And Shangkuli Formation Around The Basin

Hailaer basin is in the city of Hulunbeier,Inner Mongolia autonomous region.And it is situated on the Eerguna massif.It can be divided into five superlative structural units.Beier-Wuerxun depression have the largest acreage and the best degree of exploration among the second order structural units of Hailaer basin.They have preferable potential in hydrocarbon.Although the research of basin is mature,we still have some important geological problems to be resolved.For example,the stratigraphic correlation between the cropping area and inside the basin is a question.So this thesis choose Shangkuli Formation which in the cropping area and Tongbomiao- Nantun Formation in the basin,try to identify whether they have some connection by means of analyzing the lithology and facies,and with the help of isotopic dating and palaeontological.Shangkuli Formation has a widely distribution around Hailaer basin. It is composed of volcanic rock which explosive facies is in the majority,effusive facies is less important.It also has flaggy sedimentary rocks,oil-shale and coal bed.It contains many fossils.Tongbomiao Formation is under the well of Hailaer basin,it lies between seismic reflecting surface T3 and T4,It is composed of dark siltstone and mudstone,varicolored glutenite, it contains tuffaceous sandstone in general, there have oil-shale in part,we can often find rhyolite,andesite and pyroclastic rock. Nantun Formation lies between seismic reflecting surface T22 and T3,it is a assemblage of sedimentary rocks which are continental facies.It mainly consist of dark mudstone and sandstone, glutenite is often found around the border.Oil-shale and muddy limestone are frequently occur.By means of field geological work and log data, this thesis proposes that there are eight sorts of rocks in Shangkuli Formation and Tongbomiao—Nantun Formation.They are lava, fragments lava,welded pyroclastic rock, pyroclastic rock,banding pyroclastic rock,sedimentary pyroclastic rock, pyroclastic sedimentary rock and sedimentary rock.On the basis of the scheme,we thumb datas of 111wells and consider that: in time of Tongbomiao Formation,deposition in Beier—Wuerxun depression are circularity, coarse grain sediments are around the border.In Nantun Formation the water aquifer is deeper ,mudstone is in domination.The deposit is steady.The self-potential log is orthoscopic.Among the sections of Shangkuli Formation,the sections in the western shore of Dalai lake are consist of volcanic rock.We can identify explosive facies,effusive facies and volcanogenic sedimengtary facies and 6 intrafacies.We can also identify 4 fundamental sedimentary facies in Shangkuli Formation and Tongbomiao—Nantun Formation,they are fan delta,delta, fluvial and lacustrine.We find 10 intrafacies and 11 microfacies.On the basis of above-mentioned analysis,we try to establish the relationship between Shangkuli Formation and Tongbomiao—Nantun Formation. The main evidences are :1.Geologic time:Lots of isotopic dating datas are issued in recent.In short, the age of volcanic rocks in Shangkuli Formation is 121-142Ma; the age of volcanic rocks in Tongbomiao Formation is 117.4-123.5Ma.They all belong to Early Crataceous.2.Palaeophyte fossils:During field geological work,we have found Arguniella sp., Lycoptera, Eosestheria.This assemblage is the same as Tongbomiao—Nantun Formation.Moreover, according to the research of Wan Chuanbiao,the cryptogam assemblages in Tongbomiao—Nantun Formation are Cyathidites-Biretisporites-Podocarpidites, Cicatricosisporites-Osmundacidites- Hailaerisporites,Deltoidospora hallii-Piceaepollenites exilioides.They belong to the early stage of Early Crataceous.3.Upper and lower layers: According to the regional geology datas and drilling record,the upper and lower layers of Shangkuli Formation and Tongbomiao—Nantun Formation are all basic lava.We call them Tamulangou Formation and Yiliekede Formation.4.The comparation of lithology between them:We can find four groups of sections and well,they are:Shangkuli village,Handagai pastureland and Well De106-203A 1335.5-1833.1m;Hallaer fortress and Well Bei16 1328.0—1825.5m;Western shore of Dalai lake and Well He3 960.5—1250m;Jianzi Mountain,Zhalainuoer and Well Su8 1669.0~2197.0m.According to field geological work,we know that Shangkuli Formation has experienced the generation and transportation of the hydrocarbon.We also consider that Tongbomiao—Nantun Formation has a good oil geology condition and hydrocarbon potential.