Relative active tectonic in the metamorphic rocks of the Yaounde group: insights from geomorphic indices and topographic analysis  

作　　者：Jacques Bertrand ONANA Bernard NJOM Franois Mvondo OWONO Mero YANNAH Thierry Abou'ou ANGO Joseph Mvondo ONDOA 

机构地区：[1]Department of Earth Sciences,Faculty of Science,University of Yaounde I,Yaounde P.O Box 812,Cameroon [2]Ministry of Environment Protection of Nature and Sustainable Development,Yaounde P.O Box 3020,Cameroon [3]Department of Earth Sciences,University of Douala,Douala P.0 Box 24157,Cameroon [4]Institute of Geolological and Mining Research,Nlongkak P.O Box 411o,Yaounde,Cameroon

出　　处：《Journal of Mountain Science》2023年第10期2946-2974,共29页山地科学学报（英文）

摘　　要：The Yaounde Group(YG),representing the southern edge of the North Equatorial PanAfrican Belt,consists of quartzites,schists,micaschists,amphibolites,gneisses and migmatites.Tectonism has formed a landscape characterized by the development of linear and folded valleys and ridges,fault scarps,V-shaped valleys,incised rivers and knickpoints.These landforms constitute important markers of the regional tectonic activity,which have been computed from spatial sources such as SRTM,DEM,hydrographical networks and geomorphic indices such as AF,T,Smf,Vf,Bs,Hi,U,SI and Li.The results highlighted a mature relief consisting of asymmetric basins generated by tilting and uplift phenomena.The relative index of active tectonics(RIAT)has been estimated from an average of eight geomorphic indices evaluated on 24 subbasins,in the study area.Four classes have been defined:class 1(1.38),very high active(1.0≤RIAT<1.5);class 2(1.50-1.88),high active(1.5≤RIAT<2.0);and class 3(2.00-2.13)moderate active(2.0≤RIAT<2.5).These three classes,respectively covering 10.20%(458 km2),80.10%(3595 km2)and 9.69%(435 km2)of the study area,have shown a highly active tectonic zone,and imply the existence of a neotectonic event in the YG.This tectonic unit(YG)was also affected by the dextral NW-SE strike-slip faulting,which cross-cut the Sanaga Shear Zone(SSZ)at Ebebda and the foliation oriented NW-SE.The tilting and uplift of rocks related to Moho ascending are responsible for crustal thinning in the Cameroon basement,more important to the Adamawa Plateau from the Cretaceous age and the reactivation of existing tectonic accidents.The presence of hills,fault scarps,reverse faults,knickpoints,V and U shaped valleys and rounded mountains testify to the interaction between tectonic uplift,lithology,climate,weathering and erosion.

关 键 词：LANDFORMS Geomorphic indices RIAT Active tectonics Yaounde Group 

分 类 号：P931[天文地球—自然地理学] P588.3