Geochemistry of the Neoproterozoic sandstone associated with the Buem Structural Unit ophiolite of Northwestern Benin Republic: Implications for geodynamic evolution and paleoenvironment
Restricted accessResearch articleFirst published online December, 2025
Geochemistry of the Neoproterozoic sandstone associated with the Buem Structural Unit ophiolite of Northwestern Benin Republic: Implications for geodynamic evolution and paleoenvironment
This study involves the petrographic and geochemical assessment of Neoproterozoic metasandstones associated with the Buem Structural Unit (BSU) ophiolite in northwest Benin Republic in order to infer their tectonic setting, provenance history, and weathering in the source area. Petrographically, the metasandstones are quartz-rich with subordinate K-feldspar content and classified as quartz-rich and sublitharenite on the relevant geochemical scheme. The REE spider diagram of the rocks exhibits positive peaks for Ba, Hf and Zr and a negative peak for Sr on the chondrite profile. The chemical indexes of alteration, including CIA (23.06–80.92), PIA (16.07–62.64) and K2O/Na2O (average: 18.89) values, suggest minor to moderate weathering for the metasandstones of the BSU. On the provenance discrimination diagrams of La/Yb versus Ce, La/Th versus Hf and La/Sc versus Th/Co, BSU metasandstone samples plot predominantly in the felsic parentage field. This implies that the sediments mainly derive from felsic igneous rocks with a minor contribution from intermediate and mafic igneous sources. Tectonic setting discrimination diagrams suggest a passive continental margin in a collisional setting. The paleoclimatic condition evaluation based on major elements indicates semihumid to humid conditions. The petrographic and geochemical features of the metasandstones are consistent with siliciclastic rocks formed in a passive continental margin, similar to the West African Craton terrane. The deposition of these sediments may have started from the early stage of rifting until the Pan-African collision involving the WAC, Sahara metacraton, and Benin-Nigerian Shield, from which the Dahomeyide orogenic belt formed. These results place positive constraints on the rift–subduction–collision geodynamic model proposed for the evolution of the Dahomeyide orogen.
MooresEM. Pre–1 Ga (pre-Rodinian) ophiolites: their tectonic and environmental implications. GSA Bulletin2002; 114: 80–95. doi:10.1130/0016-7606(2002)114<0080:PGPROT>2.0.CO;2
2.
CullersRL. The controls on the major and trace element variation of shales, siltstones, and sandstones of Pennsylvanian-Permian age from uplifted continental blocks in Colorado to platform sediment in Kansas, USA. Geochim Cosmochim Acta1994; 58: 4955–7258. doi:10.1016/0016-7037(94)90224-0
3.
TaoHSunSWangQ, et al.Petrography and geochemistry of lower carboniferous greywacke and mudstones in Northeast Junggar, China: implications for provenance, source weathering, and tectonic setting. J Asian Earth Sci2014; 87: 11–25. doi:10.1016/j.jseaes.2014.02.007
4.
VermaSPArmstrong-AltrinJS. Geochemical discrimination of siliciclastic sediments from active and passive margin settings. Sediment Geol2016; 332: 1–12. doi:10.1016/j.sedgeo.2015.11.011
5.
BasuABickfordMEDeasyR. Inferring tectonic provenance of siliciclastic rocks from the chemical compositions: a dissent. Sediment Geol2016; 336: 26–35.
6.
AdjoFBNudePMGlodji AdissinL, et al.Paleoweathering, Provenance and tectonic setting of gold-bearing neoproterozoic rocks from the Atacora Structural Unit, Pan-African Dahomeyide belt, northwestern Bénin. J Afr Earth Sci2021; 183: 104327. doi:10.1016/j.jafrearsci.2021.104327
7.
KwayisiDLehmannJElburgM. Provenance and depositional setting of the Buem structural unit (Ghana): implications for the paleogeographic reconstruction of the West African and Amazonian cratons in Rodinia. Gondwana Res2022b; 109: 183–204. doi:10.1016/j.gr.2022.04.020
8.
KazapoeRWOkunlolaOArhinE, et al.Compositional characteristics of mineralised and unmineralised gneisses and schist around the Abansuoso area, southwestern Ghana. Appl Earth Sci2023; 132: 36–51.
9.
KonateSIMBolarinwaATKwayisiD, et al.Provenance and tectonic setting of greywacke and siltstone of the Nampala gold deposit, Southern Mali. Appl Earth Sci2024; 133: 129–147.
10.
TraoreEMSidibeMOlatundjiAS. Petrography and geochemistry of paleoproterozoic metasediments of Bougouni region, southern Mali: implication for provenance and tectonic setting. Appl Earth Sci2025; 134: 99–123. doi:10.1177/25726838251334053
11.
DickinsonWR.Interpreting provenance relations from detrital modes of sandstones. In: ZuffaGG, editor. Provenance of Arenites [Internet]. Springer Netherlands; 1985 [cited 2025 Apr 15]. p. 333–361. Available from: http://link.springer.com/10.1007/978-94-017-2809-6_15.
12.
McLennanSMHemmingSMcDanielDK, et al.Geochemical approaches to sedimentation, provenance, and tectonics. 1993.
13.
Kouagou N’DahDNOlobaniyiSBAdissin GlodjiLC, et al.Geochemistry of podiform chromitite and host rocks within the Buem structural unit, northwestern Benin republic: implications for the geodynamic evolution of the Dahomeyide orogenic belt. Results in Earth Sci2025; 3: 100080.
14.
AffatonPRahamanMATrompetteR, et al.The Dahomeyide Orogen: tectonothermal evolution and relationships with the Volta Basin. In: DallmeyerRDLécorchéJP, editors. The West African Orogens and Circum-Atlantic Correlatives [Internet]. Heidelberg: Springer; 1991 [cited 2023 Aug 1]. pp. 107–122. (IGCP-Project 233).
15.
JunnerNR. Geology of the gold coat and Western Togoland. Bull Gold Coast Geol Surv1940; 11: 40.
16.
JonesWB. The Buem volcanic and associated sedimentary rocks, Ghana: a field and geochemical investigation. J African Earth Sci (and the Middle East)1990; 11: 373–383. doi:10.1016/0899-5362(90)90016-8
17.
OsaeSAsieduDKBanoeng-YakuboB, et al.Provenance and tectonic setting of Late Proterozoic Buem sandstones of southeastern Ghana: evidence from geochemistry and detrital modes. J Afr Earth Sci2006; 44: 85–96. doi:10.1016/j.jafrearsci.2005.11.009
18.
KwayisiDAgraNADampareSB, et al.Two suites of gabbros in the Buem Structural Unit, of the Pan-African Dahomeyide orogen, southeastern Ghana: constraints from new field and geochemical data. J Afr Earth Sci2017; 129: 45–55. doi:10.1016/j.jafrearsci.2016.12.018
19.
KwayisiDLehmannJElburgM. The architecture of the Buem Structural Unit: implications for the tectonic evolution of the Pan-African Dahomeyide Orogen, West Africa. Precambrian Res2020; 338: 105568.
20.
AffatonP.Le Bassin des Volta (Afrique de l’Ouest): une marge passive, du protérozoique supérieur, tectonisé au Pan-Africain (600+50Ma). PhD Thesis, ORSTOMS Paris, 1990.
21.
KalsbeekFFreiDAffatonP. Constraints on provenance, stratigraphic correlation and structural context of the Volta basin, Ghana, from detrital zircon geochronology: an Amazonian connection?Sediment Geol2008; 212: 86–95. doi:10.1016/j.sedgeo.2008.10.005
22.
HoffmanPF.Did the breakout of Laurentia turn Gondwanaland inside-Out?Science1991; 252: 1409–1412.
23.
TrompetteR. Geology of Gondwana (2000). In: Pan-African-Brasiliano aggregation of South America and Africa. Balkema, 1994, pp.305–315.
24.
CabyR. Terrane assembly and geodynamic evolution of central–western Hoggar: a synthesis. J Afr Earth Sci2003; 37: 133–159. doi:10.1016/j.jafrearsci.2003.05.003
25.
Ganade de AraujoCERubattoDHermannJ, et al.Ediacaran 2,500-km-long synchronous deep continental subduction in the West Gondwana Orogen. Nat Commun2014; 5: 5198. doi:10.1038/ncomms6198
26.
GanadeCECordaniUGAgbossoumoundeY, et al.Tightening-up NE Brazil and NW Africa connections: new U–Pb/Lu–Hf zircon data of a complete plate tectonic cycle in the Dahomey belt of the West Gondwana Orogen in Togo and Benin. Precambrian Res2016; 276: 24–42. doi:10.1016/j.precamres.2016.01.032
27.
CabyR.Precambrian terranes of Benin-Nigeria and northeast Brazil and the Late Proterozoic south Atlantic fit. In: DallmeyerRD, editor. Terranes in the Circum-Atlantic Paleozoic Orogens [Internet]. Geological Society of America; 1989 [cited 2023 Sep 21].
28.
CastaingCTribouletCFeybesseJL, et al.Tectonometamorphic evolution of Ghana, Togo and Benin in the light of the Pan-African/Brasiliano orogeny. Tectonophysics1993; 218: 323–342. doi:10.1016/0040-1951(93)90322-B
29.
AttohKDallmeyerRDAffatonP. Chronology of nappe assembly in the Pan-African Dahomeyide orogen, West Africa: evidence from 40Ar39Ar mineral ages. Precambrian Res1997; 82: 153–171. doi:10.1016/S0301-9268(96)00031-9
30.
AgbossoumondeYMenotRPGuillotS. Metamorphic evolution of Neoproterozoic eclogites from south Togo (West Africa). J Afr Earth Sci2001; 33: 227–244. doi:10.1016/S0899-5362(01)80061-0
31.
DuclauxGMénotRPGuillotS, et al.The mafic layered complex of the Kabyé massif (north Togo and north Benin): evidence of a Pan-African granulitic continental arc root. Precambrian Res2006; 151: 101–118. doi:10.1016/j.precamres.2006.08.012
32.
AttohKNudePM.Tectonic significance of carbonatite and ultrahigh-pressure rocks in the Pan-African Dahomeyide suture zone, southeastern Ghana. Geological Society, London, Special Publications. 2008;297:217–231.
33.
KalsbeekFAffatonPEkwuemeB, et al.Geochronology of granitoid and metasedimentary rocks from Togo and Benin, West Africa: comparisons with NE Brazil. Precambrian Res2012; 196–197: 218–233.
34.
AttohKSamsonSAgbossoumondéY, et al.Geochemical characteristics and U–Pb zircon LA-ICPMS ages of granitoids from the Pan-African Dahomeyide orogen, West Africa. J Afr Earth Sci2013; 79: 1–9. doi:10.1016/j.jafrearsci.2012.09.015
35.
Adissin GlodjiLCBascouJPaquetteJL, et al.Geochronology and geochemistry of igneous rocks of the Dassa region, Central-Benin: evidence of an Ediacaran emplacement of alkali-calcic and alkaline plutonic and volcanic magmas. Int J Earth Sci (Geol Rundsch)2023; 112: 1331–1360. doi:10.1007/s00531-023-02293-7
36.
AttohKHawkinsDBowringS, et al.U-Pb zircon ages of gneisses from the Panafrican Dahomeyide Orogen, West Africa. EOS Trans Am Geophys Union1991; 72: 299.
37.
AffatonPGaviglioPPharisatA. Réactivation du craton ouest-africain au Panafricain : paléocontraintes déduites de la fracturation des grès néoprotérozoïques de Karey Gorou (Niger, Afrique de l’Ouest). Comptes Rendus de l’Académie des Sciences – Series IIA – Earth and Planetary Science2000; 331: 609–614.
38.
AttohKMorganJ. Geochemistry of high-pressure granulites from the pan-African Dahomeyide orogen, West Africa: constraints on the origin and composition of the lower crust. J Afr Earth Sci2004; 39: 201–208. doi:10.1016/j.jafrearsci.2004.07.048
39.
KwayisiDElburgMLehmannJ. Preserved ancient oceanic lithosphere within the Buem structural unit at the eastern margin of the West African Craton. Lithos2022a; 410–411: 106585.
40.
AttohKCorfuFNudePM. U-Pb zircon age of deformed carbonatite and alkaline rocks in the Pan-African Dahomeyide suture zone, West Africa. Precambrian Res2007; 155: 251–260. doi:10.1016/j.precamres.2007.02.003
41.
GuillotSAgbossoumondéYBascouJ, et al.Transition from subduction to collision recorded in the Pan-African arc complexes (Mali to Ghana). Precambrian Res2019; 320: 261–280. doi:10.1016/j.precamres.2018.11.007
42.
AnaniCYBonsuSKwayisiD, et al.Geochemistry and provenance of Neoproterozoic metasedimentary rocks from the Togo structural unit, southeastern Ghana. J Afr Earth Sci2019; 153: 208–218.
43.
AffatonPAguirreLMénotRP. Thermal and geodynamic setting of the Buem volcanic rocks near Tiélé, Northwest Bénin, West Africa. Precambrian Res1997; 82: 191–209. doi:10.1016/S0301-9268(97)80686-9
44.
NudePMKwayisiDTakiNA, et al.Petrography and chemical evidence for multi-stage emplacement of western Buem volcanic rocks in the Dahomeyide orogenic belt, southeastern Ghana, West Africa. J Afr Earth Sci2015; 112: 314–327. doi:10.1016/j.jafrearsci.2015.09.019
45.
Adissin GlodjiLCSaïzonouRAdjoFB, et al.Geology and geochemistry of the chromiferous mineralization in the external zone of the Pan-African Dahomeyides Belt, Northwestern Benin (Gulf of Guinea, West Africa). Int J Geosci2019; 10: 1068–1080. doi:10.4236/ijg.2019.1012061
46.
NesbittHWYoungGM. Early Proterozoic climates and plate motions inferred from major element chemistry of lutites. Nature1982; 299: 715–717. doi:10.1038/299715a0
47.
FedoCMWayne NesbittHYoungGM. Unraveling the effects of potassium metasomatism in sedimentary rocks and paleosols, with implications for paleoweathering conditions and provenance. Geology1995; 23: 921–924. doi:10.1130/0091-7613(1995)023<0921:UTEOPM>2.3.CO;2
48.
CoxRLoweDRCullersRL. The influence of sediment recycling and basement composition on evolution of mudrock chemistry in the southwestern United States. Geochim Cosmochim Acta1995; 59: 2919–2940. doi:10.1016/0016-7037(95)00185-9
49.
HarnoisL. The CIW index: a new chemical index of weathering. Sediment Geol1988; 55: 319–322. doi:10.1016/0037-0738(88)90137-6
50.
McLennanSM. Rare earth elements in sedimentary rocks: influence of provenance and sedimentary processes. In: LipinBRMcKayGA (eds) Geochemistry and Mineralogy of Rare Eorrh Elements. Mineralog. Sot. Amer, 1989, pp.169–200.
51.
HerronMM. Geochemical classification of terrigenous sands and shales from core or log data. J Sediment Res1988; 58: 820–829.
52.
TchouatchaMSKassi KassiPMbesseCO, et al.Geochemistry of onshore deposits from Rio del Rey sub-basin of the western Atlantic margin of Cameroon (Coastal basin, Southwest Cameroon): provenance and environments of sedimentation. Environ Earth Sci2022; 81: 321. doi:10.1007/s12665-022-10440-7
Armstrong-AltrinJSVermaSP. Critical evaluation of six tectonic setting discrimination diagrams using geochemical data of Neogene sediments from known tectonic settings. Sediment Geol2005; 177: 115–129. doi:10.1016/j.sedgeo.2005.02.004
55.
TobiaFHAswadKJ. Petrography and geochemistry of Jurassic sandstones, Western Desert, Iraq: implications on provenance and tectonic setting. Arab J Geosci2015; 8: 2771–2784. doi:10.1007/s12517-014-1392-0
56.
Vosoughi MoradiASariAAkkayaP. Geochemistry of the Miocene oil shale (Hançili Formation) in the Çankiri-Çorum Basin, Central Turkey: implications for Paleoclimate conditions, source–area weathering, provenance and tectonic setting. Sediment Geol2016; 341: 289–303. doi:10.1016/j.sedgeo.2016.05.002
57.
RossDJKBustinRM. Investigating the use of sedimentary geochemical proxies for paleoenvironment interpretation of thermally mature organic-rich strata: examples from the Devonian–Mississippian shales, Western Canadian Sedimentary Basin. Chem Geol2009; 260: 1–19. doi:10.1016/j.chemgeo.2008.10.027
58.
ZengSWangJChenW, et al.Geochemical characteristics of Early Cretaceous marine oil shale from Changshe Mountain area in the northern Qiang tang Basin, Tibet: implication for palaeoweathering, provenance, tectonic setting, and organic matter accumulation. Geol J2019; 55: 1–18.
59.
BhatiaMR.Plate tectonics and geochemical composition of sandstones. J Geol1983; 91: 611–627.
60.
RoserBPKorschRJ.Determination of tectonic setting of sandstone-mudstone suites using SiO2 content and K2O/Na2O ratio. J Geol1986; 94: 635–650.
61.
BhatiaMRCrookKAW. Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins. Contr Mineral and Petrol1986; 92: 181–193. doi:10.1007/BF00375292
62.
YangHKyserKAnsdellK. Geochemical and Nd isotopic compositions of the metasedimentary rocks in the La Ronge Domain, Trans-Hudson Orogen, Canada: implications for evolution of the domain. Precambrian Res1998; 92: 37–64. doi:10.1016/S0301-9268(98)00067-9
63.
ShervaisJWBranneyMJGeistDJ, et al.HOTSPOT: the snake river scientific drilling project – tracking the yellowstone hotspot through space and time. Sci Drill2006; 3: 56–57.
64.
GirtyGHRidgeDLKnaackC, et al.Provenance and depositional setting of Paleozoic chert and argillite, Sierra Nevada, California. J Sediment Res1996; 66: 107–118.
65.
van de KampPCLeakeBE. Petrography and geochemistry of feldspathic and mafic sediments of the northeastern Pacific margin. Trans R S Edinburgh: Earth Sci1985; 76: 411–449. doi:10.1017/S0263593300010646
66.
CullersRLPodkovyrovVN. Geochemistry of the mesoproterozoic lakhanda shales in southeastern Yakutia, Russia: implications for mineralogical and provenance control, and recycling. Precambrian Res2000; 104: 77–93. doi:10.1016/S0301-9268(00)00090-5
67.
PotterPE.Provenance of mudstones. In: PotterPEMaynardJBDepetrisPJ (Eds.), Mud and Mudstones: Introduction and Overview. Heidelberg: Springer, 2005, pp. 157–174.
68.
NesbittHWYoungGM. Prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations. Geochim Cosmochim Acta1984; 48: 1523–1534. doi:10.1016/0016-7037(84)90408-3
69.
CullersRL. Implications of elemental concentrations for provenance, redox conditions, and metamorphic studies of shales and limestones near Pueblo, CO, USA. Chem Geol2002; 191: 305–327. doi:10.1016/S0009-2541(02)00133-X
70.
HayashiKIFujisawaHHollandHD, et al.Geochemistry of ∼1.9 Ga sedimentary rocks from northeastern Labrador, Canada. Geochim Cosmochim Acta1997; 61: 4115–4137. doi:10.1016/S0016-7037(97)00214-7
71.
RaoWTanHJiangS, et al.Trace element and REE geochemistry of fine- and coarse-grained sands in the Ordos deserts and links with sediments in surrounding areas. Geochemistry2011; 71: 155–170. doi:10.1016/j.chemer.2011.02.003
72.
FloydPALeveridgeBE. Tectonic environment of the Devonian Gramscatho basin, south Cornwall: framework mode and geochemical evidence from turbiditic sandstones. JGS1987; 144: 531–542. doi:10.1144/gsjgs.144.4.0531
73.
SuttnerLJDuttaPK. Alluvial sandstone composition and paleoclimate; I, framework mineralogy. J Sediment Res1986; 56: 329–345.
74.
NesbittHWYoungGM.Formation and diagenesis of weathering profiles. J Geol1989; 97: 129–147.
75.
NesbittHWYoungGM. Petrogenesis of sediments in the absence of chemical weathering: effects of abrasion and sorting on bulk composition and mineralogy. Sedimentology1996; 43: 341–358.
76.
VermaSPArmstrong-AltrinJS. New multi-dimensional diagrams for tectonic discrimination of siliciclastic sediments and their application to Precambrian basins. Chem Geol2013; 355: 117–133. doi:10.1016/j.chemgeo.2013.07.014
77.
AsieduDKAgoeMAmponsahPO, et al.Geochemical constraints on provenance and source area weathering of metasedimentary rocks from the Paleoproterozoic (∼2.1 Ga) Wa-Lawra Belt, southeastern margin of the West African Craton. Geodinamica Acta2019; 31: 27–39.
78.
BrakoBAAmaduCCFoliG, et al.Petrography and geochemistry of metasedimentary rocks from the Paleoproterozoic Birimian at the Chagupana area, North-West Ghana: implications for provenance and tectonic setting. Arab J Geosci2022; 15: 1749. doi:10.1007/s12517-022-11036-y
79.
AffatonPSougyJTrompetteR. The tectono-stratigraphic relationships between the upper Precambrian and lower Paleozoic Volta Basin and the Pan-African Dahomeyide orogenic belt (West Africa). Am J Sci1980; 280: 224–248. doi:10.2475/ajs.280.3.224
80.
AnaniCYMahamudaAKwayisiD, et al.Provenance of sandstones from the Neoproterozoic Bombouaka Group of the Volta Basin, northeastern Ghana. Arabian J. Geosci2017; 10: 465.
81.
AsieduDKDampareSAsamoah-SakyiP, et al.Geochemistry of paleoproterozoic metasedimentary rocks from the Birim diamondiferous field, southern Ghana: implications for provenance and crustal evolution at the Archean-Proterozoic boundary. Geochem J2004; 38: 215–228. doi:10.2343/geochemj.38.215
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
