Late Stenian–Tonian magmatic signatures and provenance of metasedimentary rocks from the Deng-Deng area, East Cameroon

IF 2.2 4区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of African Earth Sciences Pub Date : 2025-09-23 DOI:10.1016/j.jafrearsci.2025.105859

Donald Hermann Fossi , Jonas Didero Takodjou Wambo , Evine Laure Tanko Njiosseu , Patrick Ayonta Kenne , Sylvestre Ganno , Jean Paul Nzenti

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Abstract

The Deng-Deng metasedimentary rocks crop out in the central domain of the Central African Fold Belt (CAFB), Cameroon. Field investigations and petrography reveal garnet-biotite and calc-silicate gneisses, metamorphosed under amphibolite to granulite-facies conditions. Their Chemical Index of Alteration values range from 30.61 to 55.50, suggesting weak chemical weathering under dry and cold paleoclimatic conditions, while Index of Compositional Variability values (1.03–1.90) indicate immature sediments. Provenance indicators including high Zr/Sc ratios and element am ratios such as Th/Co and La/sc, suggest derivation from felsic source rocks and varying degrees of sedimentary reworking. Tectonic setting discrimination diagrams, based on major, trace, and REE elements, point to a continental arc depositional environment. The detrital zircon age spectrum highlights two main magmatic age peaks ca. 966 Ma and ca. 797 Ma, respectively, and a maximum depositional age of 673 ± 5 Ma. These new data provide evidence of late Stenian to Tonian (ca. 929–1024 Ma) magmatism in the CAFB and reworking during the Cryogenian–Ediacaran.

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喀麦隆东部邓-邓地区晚斯坦—托尼期岩浆特征及变质沉积岩物源

喀麦隆中部非洲褶皱带（CAFB）中部地区出现了邓-邓变质沉积岩。野外调查和岩石学显示石榴石-黑云母和钙硅酸盐片麻岩，在角闪岩-麻粒岩相条件下变质。化学蚀变指数在30.61 ~ 55.50之间，表明古气候条件下的化学风化作用较弱；化学变率指数在1.03 ~ 1.90之间，表明未成熟沉积。物源指标包括较高的Zr/Sc比值和Th/Co、La/ Sc等元素比值，表明烃源岩来源于长英质烃源岩，并有不同程度的沉积改造作用。基于主量、痕量和稀土元素的构造环境判别图指向大陆弧沉积环境。碎屑锆石年龄谱显示出两个主要的岩浆年龄峰，分别为966 Ma和797 Ma，最大沉积年龄为673±5 Ma。这些新资料为中山带的晚斯坦世至晚托尼世（约929-1024 Ma）岩浆活动和低温-埃迪卡拉纪期间的岩浆活动提供了证据。

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来源期刊

Journal of African Earth Sciences 地学-地球科学综合

CiteScore

4.70

自引率

4.30%

发文量

240

审稿时长

12 months

期刊介绍： The Journal of African Earth Sciences sees itself as the prime geological journal for all aspects of the Earth Sciences about the African plate. Papers dealing with peripheral areas are welcome if they demonstrate a tight link with Africa. The Journal publishes high quality, peer-reviewed scientific papers. It is devoted primarily to research papers but short communications relating to new developments of broad interest, reviews and book reviews will also be considered. Papers must have international appeal and should present work of more regional than local significance and dealing with well identified and justified scientific questions. Specialised technical papers, analytical or exploration reports must be avoided. Papers on applied geology should preferably be linked to such core disciplines and must be addressed to a more general geoscientific audience.