检索结果-南通市图书馆

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

引用

Journal of Mountain Science 2023年第10期20卷 2946-2974页

作者： Jacques Bertrand ONANA Bernard NJOM Franois mvondo OWONO Mero YANNAH Thierry Abou'ou ANGO joseph mvondo ondoa Department of Earth Sciences Faculty of ScienceUniversity of Yaounde IYaounde P.O Box 812Cameroon Ministry of Environment Protection of Nature and Sustainable Development Yaounde P.O Box 3020Cameroon Department of Earth Sciences University of DoualaDouala P.0 Box 24157Cameroon Institute of Geolological and Mining Research Nlongkak P.O Box 411oYaoundeCameroon

The Yaounde Group(YG),representing the southern edge of the North Equatorial PanAfrican Belt,consists of quartzites,schists,micaschists,amphibolites,gneisses and *** has formed a landscape characterized by the development of linear and folded valleys and ridges,fault scarps,V-shaped valleys,incised rivers and *** 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 *** results highlighted a mature relief consisting of asymmetric basins generated by tilting and uplift *** relative index of active tectonics(RIAT)has been estimated from an average of eight geomorphic indices evaluated on 24 subbasins,in the study *** 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 *** 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 *** 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 *** 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

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Lithostructural controls in Douala-Buea Region landscape (SW Cameroon margin):Insights from morphometric analysis

引用

Journal of Mountain Science 2021年第1期18卷 68-87页

作者： Christian BALLA ATEBA Sébastien OWONA Moussa NSANGOU NGAPNA Véronique MANGA TSIMI DieudonnéMINYEM joseph mvondo ondoa Department of Earth Sciences Faculty of Sciencethe University of DoualaDouala 24157Cameroon Department of Earth Sciences Faculty of Sciencethe University of Yaounde IYaounde 812Cameroon Department of Mines and Quarries Faculty of Mining and Petroleum Industriesthe University of MarouaMaroua 814Cameroon

The Douala-Buea Region(DBR;4°-5°N,9°-10°30’E),a portion of the southern Cameroon passive margin,developed on the Proterozoic granito-gneissic basement and the Cretaceous to Recent volcanosedimentary cover,was explored in order to evaluate the lithology and tectonics controls on its landscape usingthequalitativeandquantitative geomorphological analyses based on 30 m resolution Digital Elevation Models(DEM)and field *** area displays an uneven and complex landscape differentiated into four morphological units:Douala,Nkondjock,Kumba and Buea *** Douala Unit corresponds to the Coastal Plain and is extended on the Douala-Kribi/*** Nkondjock Unit represents a middle plateau developed on a Proterozoic granito-gneissic *** Kumba Unit matches with the southernmost volcanic Western Cameroon High *** Buea Unit corresponds to the Mount Cameroon *** relief analysis through mountain-front sinuosity(Smf,1.19–1.43)and relative relief ratio(Rr,0.10–2.31)vary from one unit to *** drainage network analysis including drainage patterns,stepped longitudinalriverprofiles,theassociated morphometric indexes,notably the concavity index(IC,0.56–0.88),deviation(D,267–2912 m),basin asymmetry factor(A_(F),6.37–42.12),hypsometric integral(HI,0.10–0.29),valley floor width to valley height ratio(V_(f),0.36–2.75),elongation ratio(R_(e),0.30–0.50),watershed slope(S,6.88–88.88)and stream length gradient index(SL,0–3332)vary from one basin to another *** results also show the heterogeneous and uneven DBR landscape controlled by its lithology and active *** drainage system reveals concave to concavo-convex longitudinal river profile shapes with knick points,asymmetric basins,and fault reactivations,and highlights the tectonics activity that used to occur through the time and their control on the ***,they document the lithostructural controls on the DBR landscape evolution,extendable in the whole

关键词： Morphometric indices Lithological control Structural control Morphological units Douala-Buea Region SW Cameroon margin

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Origin and intraplate tectonic setting of mafic magmatic enclaves from the Ngaoundal area,Adamawa-Cameroon:Insights from petrography and geochemistry

引用

China Geology 2022年第4期5卷 579-594页

作者： Aliou Mamouda Sylvestre Ganno Guy Tchoupe Takam Bertin Arnold Mbita Motto Steven Hermann Donald Fossi Jean Paul Nzenti joseph mvondo ondoa Department of Earth Sciences University of YaoundéIYaoundéCameroon Institute for Geological and Mining Research(IRGM) YaoundéCameroon

In this contribution,detailed field descriptions together with petrographic and bulk-rock major,trace and rare earth elements(REE)data are used to constrain the origin and geodynamic setting of the mafic magmatic enclaves(MMEs)recently discovered within the Pan-African Ngaoundal pluton,Adamawa area,central *** investigated MMEs are dark-colored with chilled margins,and display medium to coarse-grain igneous *** mineral assemblage is either dominated by K-feldspar and carbonate(group Ⅰ),or by amphibole and plagioclase(group Ⅱ),though the overall mineral phases made of amphibole,plagioclase,K-feldspar,and biotite are similar to that of their host syenite but in different *** MMEs in Ngaoundal area are foid-gabbro in composition with SiO_(2) contents ranging between 41.52% and 43.74% and are contiguous with their host granitoids of intermediate composition(SiO_(2)=57.52% to 58.98%).The host granitoid rocks are metaluminous,and belong to the shoshonitic *** and geochemical data have revealed that the Ngaoundal MMEs derived from rapid cooling of hot injected lithospheric mantle-derived magma within cooler host granitoids magma and were emplaced in the intraplate geodynamic setting.

关键词： Mafic magmatic enclaves(MMEs) Granitoids Lithospheric mantle REE Intraplate Adamawa-Cameroon

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Geochemical characterization of the metasedimentary rocks of the Yaounde Group within the southernmost North Equatorial tectonic belt:insights into geodynamic evolution

引用

Acta Geochimica 2023年第6期42卷 1017-1034页

作者： Simon Pierre Mbola Ndzana Moise Christian Balla Ateba Germain Marie Monespérance Mboudou Moussa Nsangou Ngapna Jean Paul Sep Nlongang Solange Ipan Moise Bessong Jean Bosco Olinga joseph mvondo ondoa Sébastien Owona Paul Bilong Department of Earth Sciences Faculty of ScienceUniversity of YaoundéIP.O.Box:812Yaounde´Cameroon Institute for Geological and Mining Research P.O.Box:4110NlongkakYaounde´Cameroon Department of Earth Sciences Faculty of ScienceUniversity of DoualaP.O.Box:24157DoualaCameroon Department of Geology Faculty of ScienceThe University of BueaP.O.Box:67BueaCameroon

The Proterozoic metasedimentary rocks of the Yaounde Group on the northern edge of the Congo Shield in Central Africa were investigated to understand their provenance and depositional ***,geochemistry,and field evidence helped to subdivide the metasediments into paragneiss,mica schist,chlorite schist,and quartzite which were derived from greywacke,shale,quartz arenite,litharenite *** are immature with some mature samples,moderately weathered and reworked Neo-and Post-Archean *** earth element signatures(Chondrite Eu/Eu^(*)≤1),enrichment of light rare earth elements over the heavy ones,and the La/Sc ratio(>0.7)are compatible with those of the intermediate and felsic sources from the upper continental *** metasediments were deposited in the continental arc setting and have evolved during Proterozoic times according to the Wilson cycle to form the West Gondwana including NE Brazil.

关键词： West Gondwana North Equatorial orogenic belt Yaounde Group Neoproterozoic basin Geochemistry of metasedimentary rocks Geodynamic evolution

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Analysis of Climate Variability and Its Influence on the Hydrological Response of the Catchment Area of Kadey (East Cameroon)

引用

International Journal of Geosciences 2016年第4期7卷 539-547页

作者： Kaledje Paulin Sainclair Kouassy Ngoupayou Jules-Rémy Ndam Amidou Kpoumie Takounjou Alain Fouepe Ondoua joseph mvondo Laboratory of Engineering Geology and Alterology Faculty of Science University of Yaounde 1 Yaounde Cameroon Department of Earth Sciences Faculty of Science University of Maroua Maroua Cameroon Institute of Geological and Mining Research Hydrological Research Centre Yaounde Cameroon

Register in the framework of the International Program of Research on Water Resources Management and Protection of Ecosystems, the Congo basin in which lies the catchment area of the Kadey (2647 km2) was selected to better assess the impact climate variability on the water surface in the perspective of supply drinking water both in the rainy season and in periods of low water. Based on new data from rainfall and flow rates obtained in the last fifteen years (1998-2013), the major trends in time series and the scope of the “drought” were identified. The historical rainfall in the basin is characterized by two major ruptures rainfall in 1969 and 1999. These have generated an order deficit of 14% respectively and an excess of nearly 19%. These phenomena also affected the recurrence of cumulative rainfall throughout the Kadey basin. Here, the hydrological response to excess rainfall is over 100%. However, it appears that over the period 1970-2012, the number of years that has undergone a “severe drought” is to play down.

关键词： Catchment Area of Kadey Climate Variability Surface Water Hydrological Response

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：