Source area-weathering, provenance and tectonic setting of the campanian - Maastrichtian clay sequences in the Lower Benue Trough of Nigeria

2021 ◽  
Vol 173 ◽  
pp. 104050
Author(s):  
Anthony T. Bolarinwa ◽  
Sunday O. Idakwo ◽  
David L. Bish
2013 ◽  
Vol 5 (3) ◽  
Author(s):  
Clement Bassey ◽  
Oboho Eminue ◽  
Humphrey Ajonina

AbstractA 42 m thick outcropping portion of the Mamfe Formation is subdivided into Manyu (31 m thick) and Kesham (11m thick) Members on the basis of textural, mineralogical and structural differences. The Manyu Member (Albian) consists of folded and indurated, medium to coarse grained arkosic sandstones and thickly laminated organic-rich shales deposited in a lacustrine environment. The Kesham Member (Cenomanian) consists of subarkoses intercalated with massive green shale and mudstone deposited in a fluvial environment. The change in depositional environment was tectonically controlled. The mid Cretaceous paleogeography of the embayment was governed by the NE-SW trending “Ikom ridge” which prevented marine incursion from adjacent the Benue Sea. Evaporites found within the basin were precipitated from ocean water that was periodically spilled by strong tides and storms across the ridge into the embayment. The filling-up of the embayment to base level in the Cenomanian resulted in a shift in the depositional center downstream to adjoining lower Benue Trough. Similarity in heavy mineral composition and maturity of the Cenomanian sandstones with recent clastics in the embayment indicates their derivation from the same source terrain and relatively stable tectonic and climatic conditions at the source area since the Cenomanian time.


Geochemistry ◽  
2015 ◽  
Vol 75 (1) ◽  
pp. 105-116 ◽  
Author(s):  
Rong Liu ◽  
Zhaojun Liu ◽  
Pingchang Sun ◽  
Yinbo Xu ◽  
Dongqing Liu ◽  
...  

2014 ◽  
Vol 6 (2) ◽  
pp. 47 ◽  
Author(s):  
Ikhane P. R. ◽  
Akintola A. I. ◽  
Bankole S. I. ◽  
Oyinboade Y. T.

The petrography, as well as the major, trace and rare earth element compositions of ten (10) sandstone samples of Maastrichtian Afowo Formation exposed near Igbile, Southwestern Nigeria, have been investigated to determine their provenance, source area weathering conditions, paleoclimate and tectonic setting using petrographic analysis and Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). Results of the petrographic analysis revealed that quartz is the most dominant detrital mineral with (86%) followed by weathered plagioclase feldspar (5.10%) and rock fragments (10.9%). The quartz grain is sub-angular to sub-rounded in shape and the sandstones were classified as quartz arenites, sublitharenites and subarkoses based on framework composition of quartz, feldspar and rock fragment plots. This suggests a recycled orogen source for the sandstones and deposition in a humid climate, evidenced by the weathered feldspars. Eleven (11) major, seventeen (17) trace and fourteen (14) rare earth elements were obtained from the geochemical analysis. The major elements values range in concentration from 0.01%–81.39% with SiO2 being the dominant oxide followed by Al2O3 and Fe2O3 constituting over 95% of the major oxides; K2O, TiO2, Na2O, CaO, MgO and P2O5 made up the remaining 5%. The average ratio of SiO2/Al2O3 valued 4.31 for the sandstone is appreciably high indicating that it has been heavily weathered. The trace elements range in concentration from 0.2 ppm–1651.2 ppm with Zr being the most dominant element an indication of orogenic recycling. The rare earth elements range in concentration from 0.01 ppm–163.7 ppm with Ce having the highest concentration, depicting that the sandstones were deposited in an oxidizing environment. Also, the trace element relationship illustrated from the spider plot shows chemical coherence and uniformity of the sandstones. The chondrite normalized rare earth elements (REE) plot shows enrichment in the Light REE over the heavy REE for the sediment with strong negative Eu anomaly values between (0.57–0.69) suggesting a felsic provenance derived from upper continental crust for the sandstones.


2015 ◽  
Vol 154 (1) ◽  
pp. 1-23 ◽  
Author(s):  
HOSSAM A. TAWFIK ◽  
IBRAHIM M. GHANDOUR ◽  
WATARU MAEJIMA ◽  
JOHN S. ARMSTRONG-ALTRIN ◽  
ABDEL-MONEM T. ABDEL-HAMEED

AbstractCombined petrographic and geochemical methods are utilized to investigate the provenance, tectonic setting, palaeo-weathering and climatic conditions of the Cambrian Araba clastic sediments of NE Egypt. The ~ 60 m thick Araba Formation consists predominantly of sandstone and mudstone interbedded with conglomerate. Petrographically the Araba sandstones are mostly sub-mature and classified as subarkoses with an average framework composition of Q80F14L6. The framework components are dominated by monocrystalline quartz with subordinate K-feldspar, together with volcanic and granitic rock fragments. XRD analysis demonstrated that clay minerals comprise mixed-layer illite/smectite (I/S), illite and smectite, with minor kaolinite. Diagenetic features of the sandstone include mechanical infiltration of clay, mechanical and chemical compaction, cementation, dissolution and replacement of feldspars by carbonate cements and clays. The modal composition and geochemical parameters (e.g. Cr/V, Y/Ni, Th/Co and Cr/Th ratios) of the sandstones and mudstones indicate that they were derived from felsic source rocks, probably from the crystalline basement of the northern fringe of the Arabian–Nubian Shield. The study reveals a collisional tectonic setting for the sediments of the Araba Formation. Palaeo-weathering indices such as the chemical index of alteration (CIA), chemical index of weathering (CIW) and plagioclase index of alteration (PIA) of the clastic sediments suggest that the source area was moderately chemically weathered. On the northern margin of Gondwana, early Palaeozoic weathering occurred under fluctuating climatic conditions.


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