| research data, there are still many puzzling urgent tectonic atderns about Babiima hasin. Based on integration of stacks of geophysical data, tectonic achievements and testing data of the basin and its neighborhoods, evolutive settings, deformation characteristics and evolutive processes of different extensional structural types in different tectonic periods of the middle area of Jizhong depression , are focused on in this paper.According to crust extansional dynamic resource. extensional structures are divided into three types, which are well developed and exhibited clearly in the middle area of Lizhong doression. which should be honored "extensional structural museum".Under middle Mesozoic strong sinistral shear compressive back magamatic activity -in Taihang mountain area culminated. Fuping and Zanhuang dome-like metamorphic assemblages formed and uplifted quickly with thermal process. Nowdays, the remained mountain-cover over the dome denoted large area of deposit cover that lay at the western wing of pre-Jurassic large complex Jixi anticline striking NNE at the beginning. Circum- metamorphic-assemblage tenacitive shear zone on earth surface indicates its violent uplift and large scale lateral extensional detachment. And thus resulted in three-in-one of magma intrusion-thermal vault-metamorphic assemblage and three interdependent evolutive processes of thermal-uplifting, petrographic-eroding and lateral-detaching. By integratedanalysis of regional tectonic settings, magma isotope ages, geothermal gradient and strata involvecyn the detachment,the conclusion has been reached that the assemblage detached laterally on large scale in late Cretaccous after its violent uplift, leading to the tectonic environment of extending in the west anding in theeasCto which corresponded^ by western rifting and eastern uplifting, namely, trierifted zone acted as the rear extensional zone, yet the eastern zone from today's eastern fringe of Jizhong depression to the western fringe of Cangxian uplift played the role of front compressed thrust zone, and between the both zones is transitional zone.Thejyesteni zone bounded by Taihang fault appeared halfgraben-like with rifting in the west and t, in which sediment thickness comesto 6000m. The eastern cornpresseo^zone presented nappe thrusting from west to east in which a series of pre-Cenozoic allochthony block came into being because of decollement westward by inverted tectonic movement in the Cenozoic extensional settings. Supported by this thought, the original idea that Renqiu buried hill possibly is an allochthony block is reached. Deformation in the transitional zone is less strong and leaded to simple structures, and its detachment faces are fairly clear on seismic profiles basinwhich extended under regional ext^hgar stress, ExlsusJomLsttUCtural systems are composedb^jjfitachnienl faults. and The differences in deformative characteristics, geological functions etc. of this three factors are discussed and summed up in detail. Extensional deformations occurring in brittle crust area depend on close combinative action of basement detachment faults and basement growth faults, and devotion of the former is far more than of the later. The transverse zones adjust or transform regional extension diversity.A. series of overlapping bounding faults of the eastern middle area belonging to positive invertedsttjjcjujje were developed hasprHfln^Ihe-fronL thrust zonelvhich was-fjanned during early period of metamorphic assemblages lateral detachment process. Based on the example or Maxi fault, basement growth tauTts^s segmentation features, associated structures, the horizontal displacement distances, the active stages and the evolution etc. are analyzed thoroughly in this paper. Taidong fault as a typical basement detachment fault, formed during early processes of the metamorphic assemblages detaching, acted continuously in early Cenozoic and extended violently above all, and weakened after Es4obviously. The, fggjier is like a dish with limited scale, deep-wat...
|
PDF Full Text Request