干旱区生态环境知识资源中心(Arid): Influence of biotic vs abiotic processes on the genesis of non-marine carbonates along the Cameroon Volcanic Line (Cameroon) and palaeofluid provenance

Arid

DOI	10.1002/dep2.154
	Influence of biotic vs abiotic processes on the genesis of non-marine carbonates along the Cameroon Volcanic Line (Cameroon) and palaeofluid provenance
	Bisse, Salomon Bertrant; Ekoko, Bokanda Eric; Gerber, Jacques; Ekomane, Emile; Franchi, Fulvio
通讯作者	Franchi, F (corresponding author), Botswana Int Univ Sci & Technol BIUST, Dept Earth & Environm Sci, Palapye, Botswana.
来源期刊	DEPOSITIONAL RECORD
EISSN	2055-4877
出版年	2021-06
英文摘要	Continental spring carbonates are perfect examples of the interaction of biotic and abiotic processes, and they preserve evidence of the velocity of the flow and the chemical composition of the spring water. This study focuses on non-marine carbonates from fossil and active springs from the Bongongo and Ngol areas along the Cameroon Volcanic Line in South-West Cameroon. Here, hydrothermal fluids reach the surface giving rise to small thermal springs, with temperatures between 31 and 49 degrees C, and streams creating waterfalls, terracettes and barrage carbonate deposits. Petrographic analyses of these carbonates revealed that they are made up of stacked laminae of fibrous coarse crystals of low-Mg calcite and laminae of alternate microsparite and micrite. The fibrous coarsely crystalline calcite, often with feather-like fabric, grows from thin layers of micrite and peloids. Filaments of putative microbial origin are preserved within this peloidal micrite. The laminated microsparite and micrite microfacies is characterised by an intricate mesh of hollow filaments of microbial origin. The long feather-like crystals of calcite formed in fast-flowing water where the enhanced CO2 degassing has favoured the precipitation of CaCO3. The laminated micrite and microsparite, on the other hand, are probably formed in ponds where degassing and CO2 removal was lower and the calcite precipitation was fostered by microbial activity. The fast-forming carbonates show higher Ce contents and very low total rare earth elements, revealing a preferential uptake of Ce with respect to other rare earth elements. This process would explain the positive or null Ce anomaly in continental spring carbonates elsewhere. The geochemical composition of these carbonates can be used as proxy for the characterisation of fluid/rock interactions between the groundwater and the substratum and for the characterisation of the sources of calcium and other elements that constitute tufa and travertines. The samples from Ngol are characterised by light rare earth element enrichment while those from Bongongo are overall enriched in heavy rare earth elements. Carbonates from both localities have a strong positive Eu anomaly (>4), suggesting a contribution from deep-seated, hydrothermal, crustal fluids in contact with volcanic rocks and the breakdown of plagioclase from the Cameroon Volcanic Line alkali basalts.
英文关键词	Cameroon Volcanic Line low-Mg calcite rare earth elements spring deposits trace elements travertines
类型	Article ; Early Access
语种	英语
开放获取类型	gold
收录类别	SCI-E
WOS记录号	WOS:000667284700001
WOS关键词	RARE-EARTH-ELEMENTS ; FOSSIL-SPRING TUFAS ; QUATERNARY TRAVERTINE ; HYDROTHERMAL FLUIDS ; CALCITE DENDRITES ; CERIUM ANOMALIES ; KHARGA OASIS ; KANYE BASIN ; ANTI-ATLAS ; IN-VITRO
WOS类目	Geology
WOS研究方向	Geology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/353011
作者单位	[Bisse, Salomon Bertrant; Ekomane, Emile] Univ Yaounde I, Dept Earth Sci, Yaounde, Cameroon; [Ekoko, Bokanda Eric] Univ Buea, Dept Geol, Buea, Cameroon; [Gerber, Jacques] Univ Witwatersrand, Microscopy & Microanal Unit, Johannesburg, South Africa; [Franchi, Fulvio] Botswana Int Univ Sci & Technol BIUST, Dept Earth & Environm Sci, Palapye, Botswana
推荐引用方式 GB/T 7714	Bisse, Salomon Bertrant,Ekoko, Bokanda Eric,Gerber, Jacques,et al. Influence of biotic vs abiotic processes on the genesis of non-marine carbonates along the Cameroon Volcanic Line (Cameroon) and palaeofluid provenance[J],2021.
APA	Bisse, Salomon Bertrant,Ekoko, Bokanda Eric,Gerber, Jacques,Ekomane, Emile,&Franchi, Fulvio.(2021).Influence of biotic vs abiotic processes on the genesis of non-marine carbonates along the Cameroon Volcanic Line (Cameroon) and palaeofluid provenance.DEPOSITIONAL RECORD.
MLA	Bisse, Salomon Bertrant,et al."Influence of biotic vs abiotic processes on the genesis of non-marine carbonates along the Cameroon Volcanic Line (Cameroon) and palaeofluid provenance".DEPOSITIONAL RECORD (2021).