Research Of Tectonic Framework And Recovery Of Denudation And Prototype Basin In Yimin Formation, Beier Depression

Hailar-Tamsag Basin is located in the northeastern China and was produced bya collision which cased from a extrusion process between the North China Plate andSiberian plate in the late Paleozoic and early Mesozoic transition period. BeierDepression is located in Central rift zone in Hailar-Tamsag Basin. The tectonicprocesses of Beier Depression can be divided into three steps: Riftperiod,Rift-Depression period and Depression period. A large amount of stratumswhich formed from Late Mesozoic to the Quaternary period can be found in thedepression. These stratums can be arrayed in such manner which formed from theearly period to the new period: Tongbomiao Formation, Natun Formation,Damoguaihe Formation, Yimin Formation in Lower Cretaceous; QingyuangangFormation in Upper Cretaceous; Huchashan Formation in Tertiary and stratums inQuaternary.Beier Depression can be divided into ten3rdtectonic units: Beibei sub-sag, Beixisub-sag, Aonaohai sub-sag, Xileaobao sub-sag, Sunainuoer structural zone,Huhenuoren Fault nose structural zone, Moduohuoer fault-nose tectonic zone,Sudeerte burial hill structural zone, Bulehongbusi fault-uplift tectonic zone and EastWulannuoer fault-nose tectonic zone。Now About4oilfield had been found in BeierDepression: Sudeerte oilfield, Bayantala oilfield, Huhenuoren oilfield and Beizhongoilfield.Using the manner of three-dimensional seismic interpretation in Beier Depression,the seismic reflection zone in this area can be divided into8parts:T04reflection zone,T1reflection zone, T2reflection zone, T21reflection zone, T22reflection zone, T23reflection zone, T3reflection zone and T5reflection zone. In the lecture the key todivide the seismic reflection zones in Beier Depression are the causes of seismicsequence. We can divide the seismic reflection zones in this area into two parts by usingthe method above: one is Tectonic unconformity reflection zone and the other isSedimentary unconformity reflection zone On the one hand, about5reflection zonesare included into tectonic unconformity reflection zone:T04,T1,T22,T23and T5reflection zone. Moreover, by the manner of the background of sequence boundary produced, we also can divide the tectonic unconformity reflection into two parts:Extrusion sequence boundary, which cased by folds, and Extension sequence boundary,which cased by faults. Based on this theory, we can standardize those5reflection zonesin a reasonable system, that T5reflection zone is the bottom surface of LowerCretaceous, which can be defined as a1st tectonic unconformity reflection in extensionenvironment; T23reflection zone is the top surface of1stsection, Nantun Formation,which can be defined as2ndtectonic unconformity reflection in extension environment;T22reflection zone is the top surface of Nantun Formation, which can be defined as1sttectonic unconformity reflection in extension environment; T04reflection zone is theinterface of Yimin Formation in Lower Cretaceous and Qingyuangang Formation inupper Cretaceous, which can be defined as1sttectonic unconformity reflection inextension environment; T02reflection zone is the top surface of QingyuangangFormation in upper Cretaceous, which can be defined as1st tectonic unconformityreflection in extrusion environment. On the other hand, Sedimentary unconformityreflection zone includes3other reflection zones:T2,T21and T23reflection zone.T2reflection zone is the top surface of Damoguaihe Formation, T21reflection zone is thetop surface of1st section, Damoguaihe Formation and T23reflection zone is the topsurface of Tongbomiao Formation. With the determination of1sttectonicunconformity reflection. We can divide the cover of platform in Beier Depression into4structural layers: Structural layer of Rift, which includes Tongbomiao Formation andNantun Formation; Structural layer of Rift-Depression, which includes DamoguaiheFormation and Yimin Formation; Structural layer of Depression, which includesQingyuangang Formation and Structural layer of Atrophy, which includes CenozoicErathem.This lecture has finished the researching about tectonic features in this area,which includes three parts: tectonic style, tectonic mode and fault features. Firstly inthe lecture the author has summarized characteristics about the tectonic style anddivides the tectonic style into two parts: extensional tectonic style and strike-sliptectonic style. One the one hand, in Beier Basin, extensional tectonic style includes4types: Stepped fault combinations, Book-inclined faults, Slide faults and Graben-horstfault combinations. On the other hand, strike-slip tectonic style includes4types in thisarea: Positive flower structure and Negative flower structure. Positive flower structureis produced by the pressure torsion stress field, while negative flower structure isformed in a tension torsion stress field environment. Secondly the researching oftectonic mode in Beier Basin has been divided into two parts: Researching of construction mode and Researching of reconstruction mode. Moreover, constructionmode also can be divided into two parts by the rule of tectonic development. One isconstruction mode of rift structural layer and the other is construction mode ofrift-depression Structural layer. In Beier Basin construction mode of rift structurallayer has included three parts: single-fault construction mode, single stepped-faultconstruction mode and single stepped-fault slot construction mode; while constructionmode of rift-depression Structural layer can be divided into two parts: type of fractureand type of non-fracture. In this area the reconstruction mode has included three types:Long-breaking type, Slide-fault type and Rotary type. At last, this lecture has dividedthe fault period in Beier Basin into6parts: Fault in rift period, fault in final stage of1stsection, Nantun Formation, fault in final stage of2ndsection, Nantun Formation,fault in rift-depression period, fault in final stage of Yimin Formation and fault inreversion period.In the lecture the author uses two kinds of methods to finish the researchingabout the denudation recovery in Yimin Formation, Beier Basin. One is the method ofvitrinite reflectance and the other is the method of interval transit time. Both these twokinds of method have advantages and disadvantages. On the one hand, the mostsignificant advantage of the method of interval transit time is the measured data whichwas came from the well was always dependable and reasonable. However, thismethod’s authority is always challenged by both the density of wells and the data ofburied death which happened afterdenudation. On the other hand, the advantage of themethod of vitrinite reflectance is that the Seismic data is affluent and the coverage iswide, but this method makes doubt in the diversity of geological model and theaccuracy of the speed data.Furthermore, in the lecture ancient tectonic units of Yimin Formation in BeierBasin has been divided into7parts: Wunan secondary depression, Beixi secondarydepression, Beizhong secondary depression, Beidong secondary depression,Bayantala structural zone, Beizhong uplift zone and Buleihongbusi uplift zone. Beixisecondary depression distributed along the North-East path. Beizhong secondarydepression is similar with Beixi secondary depression and it also distributed along theNorth-East path. Beizhong uplift zone located between Beizhong secondarydepression and Beixi secondary depression, it distributed along the North-East path.Buleihongbusi uplift zone located between Beizhong secondary depression andBeidong secondary depression, it was parallel with Beizhong secondary depressionand Beidong secondary depression,and distributed along the North-East path. Bayantala structural zone located between Buleihongbusi uplift zone and Wunansecondary depression, it distributed along the North-West path.