Multi-method characterization of the recent sediment from the Dibi subsidence lake in the tropical Adamawa region (central Cameroon): Implications for the palaeoenvironmental reconstruction  

作　　者：Agathe Catherine N.Ngo Ndje Chavom Bachirou Mfayakouo Soureiyatou Fadil-Djenabou Paul-Desire Ndjigui 

机构地区：[1]Department of Earth Sciences,Faculty of Science,University of YaoundéI,PO.Box 812,Yaoundé,Cameroon [2]Department of Earth Sciences,Faculty of Science,University of Maroua,PO.Box 814,Maroua,Cameroon [3]Department of Life and Earth Sciences,Higher Teacher's Training College,University of Maroua,PO.Box 55,Maroua,Cameroon

出　　处：《International Journal of Sediment Research》2024年第1期110-130,共21页国际泥沙研究（英文版）

摘　　要：The evolution and functioning of various tropical ecosystems is poorly understood due to a lack of quan-titative techniques to characterize the physicochemical composition of soils and sediment.Here,a detailed multi-method study of lithological changes is provided from a core taken from the silted-up Dibi subsi-dence lake(central Cameroon).To unravel the provenance of sediment,mineral constituents,and organic matter sources,an array of tools are applied including a spectrophotometer,a laser particle sizer,Rock-Eval pyrolysis,X-ray diffractometer(XRD),a portable X-ray fluorescence(XRF)spectrometry,and an inductively coupled plasma-atomic emission spectroscopy(ICP-AES)instruments.The studied core consists of light-colored deposits at the base(Unit 1)overlain by dark humic deposits(Unit 2).The sediment is very well graded(grading index Sd<0.35Ф),indicative of bottom suspended to rolling transport.Unit 1 is charac-terized by relatively low values of total organic carbon(TOC:2%-5%)whereas the dark Unit 2 has high contents of T0C(10%-33%).The core shows a high oxygen index(OI)value(average=207 mg carbon dioxide(CO_(2))/g TOC)and a low hydrogen index(HI)value(average=107 mg hydrocarbon(HC)/g TOC).This indicates highly altered organic matter(OM),likely from decomposed terrestrial plants.The chlorophyll-a fingerprint(peak around 675 nm)also reveals an autochtonous primary production of organic matter.The mineralogical assemblage of Unit 2 comprises kaolinite,quartz,feldspars,montmorillonite,ilmenite,siderite,gibbsite,rutile,and anatase whereas that of Unit 1 is similar but differs with the presence of illite and the absence of gibbsite.The high titanium dioxide(TiO_(2))and zirconium(Zr)contents confirm that the source rocks also are comprised of granites,and gneiss without volcanic rocks,such as basalts and tra-chytes.The source rocks have been intensively weathered using some parameters such as In(Al_(2)O_(3)/Na_(2)O),K_(2)O/Rb,K/Al,and weathering indices,where Al_(2)O_(3) denotes aluminum oxide,Na_(2)O denotes sodium o

关 键 词：Recent lacustrine sediment Organic matter MINERALOGY Geochemistry Palaeoenvironmental reconstruction Adamawa region 

分 类 号：P619.228[天文地球—矿床学] P343.5[天文地球—地质学]