The Remote Sensing Interpretation Of Beijing-erenhot Region And Its Deep Structural Sigiificanoe

SinoProbe–02project provide a deep seismic reflection profile from Guantingreservoir to the south and to Erlianhaote near the Sino-Mongolian border to thenorth.Important tectonic units like Northern margin of the North China platform andXing-Meng orogenic belt are crossed by this profile.Because of polytectonicmovement like strong collision orogeny and extensional rifting, exposed stratum ofthis area is limited. The major geological boundaries were usually determined by theexplanation of gravity and magnetic anomalies. Location of the fractural structures isstill with a lot of controversy.Emplacement age of magma provide a well constraintfor the period of tectonic movement by reason that all the fractural structures of thisarea do not go through magmatite by the reflection of the deep seismic reflecionprofile.From the interpretation of remote sensing images of lineaments, U-Pb dating ofgranites, and the estimation of emplacement depth by hornblende&biotiteAl-barometer, we obtain a new understanding of the tectonic evolution process of thisarea.(1)According to the consequences of interpretation of Linear Tectonics, fractureof this area can be devided into four phase with the trending of EW, NE, NNE andNW.Combined with the reaction of deep structure,we provide a new proof for theWestern extension of Xar Moron River Fault. We believe the western extension passthrough Sanggin Dalai and Jurh(south of Ondor Sum) and finally join up withChifeng-Bayan Obo fracture zone at the southeast of Boin Sum. The principal stressof the area from Linxi to Ujimqin is trending NW.(2)Large-scale magmatism had taken place juring the late Permian to earlyTriassic（246.2±1.4~275±1.3Ma）in the west section of Inner Mongolia Paleo-upliftbelt according to the consequence of U-Pb dating. Combined with isotopic age,petrology, geochemistry character and the deep seismic reflection characteristicspublished by other researchers, we consider that the tectonic environment of thenorthern margin of North China craton had changed from continent-continent collision setting to post-collisional extension setting during the end of earlyPermian(275Ma).(3)the estimation of Emplacement depth of Yangjiafangzi rockmass,Damiaogongsi rockmass and Shunchenggongshe rockmass are estimated byhornblende&biotite Al-barometer.The results show that this area has rifted at least7km from the end of early permian on. Contrast with the consequence of the study ofEast Inner Mongolia Paleo-uplift by Zhang Shuanhong. There is a discrepancy inerosion and uplift between the east phase and the west phase of Inner MongoliaPaleo-uplift belt from Late Palaeozoic up to now.