Provenance of clastic sediments: A case study from Cameroon, Central Africa

IF 2 4区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY
Victorine Ambassa Bela , Armel Zacharie Ekoa Bessa , John S. Armstrong-Altrin , Francis Aonsi Kamani , Estelle Diane Biami Nya , Gabriel Ngueutchoua
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引用次数: 1

Abstract

The provenance of clastic sediments in stream beds, river terraces, rivers, swamps, lakes and beaches from different geological settings was investigated based on their compositional and geochemical variations. The geochemistry data of 622 sediment samples from 22 sites in the Cameroon were compiled to infer the provenance. The results suggest that, their mineralogy is dominated by quartz, low amount of feldspars, clay minerals, heavy minerals, ferric minerals, and rock fragments. The SiO2/Al2O3 ratio indicate that the sediments of Cameroonian region are mostly rich in quartz and clay-minerals. The enrichment of K2O/Na2O ratio implies plagioclase disintegration as K-feldspar during weathering and/or K-reintroduction in the system during diagenesis. The sediments are rich in light rare earth elements (LREE) and classified as shale, Fe-shale, Fe-sand, wacke, arkose, litharenite, sublitharenite, and quartzarenite. The sediments are composed of detritus derived from felsic igneous rocks, which correspond to the geology of the source areas. Weathering indices such as chemical index of alteration (CIA), chemical index of weathering (CIW), plagioclase index of alteration (PIA) and, A–CN–K (A=Al2O3, CN=CaO∗ + Na2O, K=K2O) plot indicated that the source rocks are subjected to low, moderate and intense weathering.

碎屑沉积物的来源:以中非喀麦隆为例
研究了不同地质背景下河床、河流阶地、河流、沼泽、湖泊和海滩碎屑沉积物的化学成分和地球化学变化。对喀麦隆22个地点的622个沉积物样品的地球化学数据进行了整理,以推断物源。结果表明,其矿物组成以石英为主,少量长石、粘土矿物、重矿物、铁质矿物和岩石碎块。SiO2/Al2O3比值表明喀麦隆地区沉积物主要富含石英和粘土矿物。K2O/Na2O比值的富集表明斜长石在风化过程中作为钾长石崩解,或在成岩作用过程中钾元素重新进入体系。沉积物富含轻稀土元素(LREE),可分为泥页岩、铁泥页岩、铁砂、砂岩、长石砂岩、岩屑屑岩、次岩屑屑岩和石英屑岩。沉积物由长英质火成岩的碎屑组成,与源区的地质条件相对应。化学蚀变指数(CIA)、化学风化指数(CIW)、斜长石蚀变指数(PIA)和A - CN - K (A=Al2O3, CN=CaO∗+ Na2O, K=K2O)图表明烃源岩受低、中、强风化作用。
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来源期刊
Solid Earth Sciences
Solid Earth Sciences GEOSCIENCES, MULTIDISCIPLINARY-
CiteScore
3.60
自引率
5.00%
发文量
20
审稿时长
103 days
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