Multi-stage Activi-ty,Paleo-stress Field and Dynamic Background of the Sanzao Fault Zone Since Early Creta-ceous in the Zhuhai Area,Guangdong Province
The Sanzao fault zone in the Zhuhai area,Guangdong Province is the southwest extension of the Lianhuashan fault zone,and its spatial distribution,deformation characteristics and tectonic evolution are of great significance for understanding the tectonic processes of the Mesozoic and Cenozoic in southeastern South China.The spatial distribution of the Sanzao fault zone,the geometric and kinematic characteristics of different deformation stages were identified,through active fault mapping,detailed tectonic analysis,geo-physical exploration and drilling.The stress field and their direction in different periods were inverted,based on the newly identified fault planes and slickensides data.Furthermore,combined with the regional tectonic evolution,it is regarded that the Sanzao fault zone was influenced by five phases of paleo-tectonic stress field since the early Cretaceous,characterized by multi-stage compression or extension in different directions.These phases responds to a series of regional tectonic events since the late Mesozoic respectively.Phase Ⅰ NW-SE extension(D1)may record the regional crustal extension during the early Cretaceous.Phase Ⅱ NW-SE compression(D2)may be related to the compression events that caused the reversed faulted basins in South China and deformation and metamorphism of Changle-Nanao fault zone during the late early Creta-ceous to early late Cretaceous.Phase Ⅲ nearly SN compression(D3)may be related to the compression events which produced the regional unconformity between the Late Cretaceous and Paleogene strata.PhaseⅣnearly EW compression(D4)may be controlled by the expansion of the South China Sea oceanic basin be-tween the Oligocene and Miocene.Phase Ⅴ NW-SE extension(D5)may be related to the sustained westward subduction of the Philippine Sea Plate from the Pliocene to Quaternary.
Sanzao Fault Zonemulti-stage activitypaleo-stress fieldEarly Cretaceousthe Zhuhai area,Guangdong province
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