Contents lists available at ScienceDirect Journal of African Earth Sciences journal homepage: www.elsevier.com/locate/jafrearsci 40 Ar– 39 Ar ages from the Sabongari and Nana igneous complexes within the central part of the Cameroon Line (Central Africa) Emmanuel Njonfang a,* , Marinella A. Laurenzi b , Pauline Wokwenmendam Nguet c , Domenico Cozzupoli d a Laboratoire de Géologie, Ecole Normale Supérieure, Université de Yaoundé I, B.P. 47, Yaoundé, Cameroon b Istituto di Geoscienze e Georisorse, Area della Ricerca CNR, Via G. Moruzzi, 1, 56124 Pisa, Italy c Institut de Recherches Géologiques et Minières/Antenne de Recherches Géophysiques et Volcanologiques, Ekona, B.P. 370 Buéa, Cameroon d Department of Geological Sciences, University of Studies "Roma TRE", Largo S. Leonardo Murialdo 1, 00146 Roma, Italy ARTICLE INFO Keywords: Cameroon line magmatism 40 Ar– 39 Ar dating Sabongari complex Nana complex ABSTRACT The Sabongari and Nana volcano–plutonic complexes are two of about sixty complexes that outcrop along the Cameroon Line. In both complexes, granites and rhyolites are the prevalent rock types among plutonic and volcanic rocks, respectively. The Nana complex has never been dated, while data ranging from 77 to 49 Ma have been reported for the Sabongari intrusive rocks. These ages appeared inconsistent with field relationships, the oldest ones 77 and 74 Ma being obtained on microgranites that form a WSW–ENE alignment of small plugs within the main granite. We performed 40 Ar– 39 Ar laser step–heating analyses on a plutonic and a volcanic rock for each complex. The age obtained on Sabongari granite, 57.70 ± 0.44 Ma, is about 1 Ma older than the age obtained on a related trachyte, and consistent with field relationships. Rocks from the Nana complex are younger than those from Sabongari, ranging from 52 to 49 Ma. This is the second paper with 40 Ar– 39 Ar data on the Cameroon Line anorogenic complexes after that on the Hossere Nigo complex, sited at about 240 km to the NE of the study area. Both results challenge earlier K–Ar and Rb–Sr model ages along the Cameroon Line. More 40 Ar– 39 Ar data on a large number of complexes are necessary to better understand their spatial relationships over time. 1. Introduction The Cameroon Line (CL) is one of the major Tertiary tectono–- magmatic features in Africa. It extends from the Pagalu Island in the Atlantic Ocean to the Kapsiki plateau on the continent, forming a ca 1600 km linear alignment of magmatic edifices. Along the continental part (Fig. 1a), more than sixty small volcano–plutonic complexes co- exist with volcanic massifs. The available geochronological data along this CL are more abundant on volcanic (see Mbowou et al., 2012 for compilation) than on plutonic complexes (Njome and de Wit, 2014). Furthermore, data are mainly based on K–Ar and Rb–Sr analyses, using methods that require assumptions about the initial isotopic ratios of analyzed minerals in order to calculate ages. For example, the only 40 Ar– 39 Ar age published on a CL pluton (65.0 ± 0.8 Ma) disagrees with the K–Ar data of the same sample (69–82 Ma) (Kamden et al., 2002). Here we present new 40 Ar– 39 Ar ages of plutonic and associated volcanic rocks from two complexes in the Tikar plain, called Sabongari (or Mba Namboué) and Nana. Both are characterized by near surface emplacement levels (presence of miarolitic cavities in the rocks). The Sabongari granites have been previously dated (Rb/Sr and K/Ar) by Lasserre (1978) and Cantagrel et al. (1978), between 77 and 49 Ma. However, these data are inconsistent with field relationships (see Fig. 2), and show a quite long interval of time across a few kilometers wide pluton. The Nana complex has not been dated previously. Vol- canic rocks associated to the plutonites in the Tikar plain are dated, enabling us to test their relative emplacement history. 2. Geological setting Seven alkaline magmatic complexes along the CL (Fourougain, Nana, Bitou, Sabongari, Mbafé, Pamsa, Pandé) are located in the Tikar plain (Fig. 1b). The Sabongari, Nana and Pandé complexes form a SW–NE alignment of isolated massifs. Petrological data have been re- cently obtained from these complexes, except on Fourougain and Bitou (Njonfang et al., 2013 and references therein). This new data show that https://doi.org/10.1016/j.jafrearsci.2018.06.006 Received 17 November 2017; Received in revised form 6 June 2018; Accepted 7 June 2018 * Corresponding author. E-mail address: enjonfang@yahoo.fr (E. Njonfang). Journal of African Earth Sciences 147 (2018) 20–27 1464-343X/ © 2018 Published by Elsevier Ltd. T