Zircon trace element geochemistry and Ti‐in‐zircon thermometry of the Linté Pan‐African granitoids, Central Cameroon: Constraints on the genesis of host magma and tectonic implications. (15th July 2021)

• Record Type: Journal Article
• Authors: Ayonta Kenne, Patrick; Tanko Njiosseu, Evine Laure; Ganno, Sylvestre; Ngnotue, Timoleon; Fossi, Donald Hermann; Hamdja Ngoniri, Alexis; Nga Essomba, Philomene; Nzenti, Jean Paul
• Is Part Of: Geological journal. Volume 56:Number 9(2021)
• Page Start: 4830
• Page End: 4848
• Publication Date: 2021-07-15
• Subjects: Cameroon -- Central African Fold Belt -- continental crust -- LA‐ICP‐MS zircon geochemistry -- magmatic arc -- Ti‐in‐zircon thermometer; Geology -- Periodicals; 551
• DOI: 10.1002/gj.4208
• Languages: English
• ISSNs: 0072-1050

Abstract

Abstract : The Linté area belongs to the central part of the Adamawa‐Yadé Domain (AYD) within the Pan‐African Central African Fold Belt (CAFB) in Cameroon. This area is dominated by Neoproterozoic high‐K calc‐alkaline syenite and monzonite intruding Archean to Palaeoproterozoic gneisses. In this contribution, trace element compositions of zircon obtained using laser ablation inductively coupled plasma mass spectrometry are used to constrain the petrogenesis and tectonic setting of Linté area. The analysed zircon grains display restricted ranges of Hf contents with an average of 8, 197 ppm in syenite, 8, 220 ppm in alkali‐feldspar syenite, and 9, 026 ppm in monzonite. They display high Th/U ratios (>0.5) typical of magmatic zircons. The monzonite zircons have a higher ∑REE content (483.42 ppm) than the syenite zircons (237.70 ppm). The chondrite‐normalized rare‐earth element (REE) diagram of Linté samples shows very similar patterns, characterized by a steeply rising slope due to important heavy rare‐earth element enrichment relative to light rare‐earth element, with distinctive positive Ce and negative Eu anomalies. The application of the Ti‐in‐zircon thermometer reveals a wide range of crystallization temperatures (574–1, 137°C for syenites and 713–1, 008°C for monzonite), implying a deep level of melting, likely within the lower continental crust of the CAFB. The integration of geochemical behaviours of some trace elements (U, Hf, Zr, Ce, Th, and Nb), together with discrimination diagrams, suggests the crystallization of a continental crust‐derived magma under variable oxidation states and emplacement in a magmatic‐arc setting. This finding represents and adds on to the N‐S geodynamic convergence model between the AYD and the northern border of the Congo Craton. Abstract : (a) U/Yb versus Hf (a) and U/Yb versus Nb/Yb (b) diagrams showing the continental crust origin of the host magma of the Linte magmatic zircon granitoids, and their emplaced in arc‐related setting (c). The Linte zircons are magmatic in origin. Their host magma was derived from continental crust. Crystallization temperatures range from 574 to 1137°C for syenite zircons and from 713 to 1008°C for monzonite zircons. The host granitoids were emplaced in a compressive magmatic‐arc setting.