Paleocurrent analysis, petrographic, geochemical and statistical appraisal of Neoproterozoic siliciclastic sediments, NE Voltaian Basin, Ghana: a multidisciplinary approach to paleogeographic reconstruction

Abstract

This study used sedimentary structures, facies analysis, petrographic studies, statistical techniques and geochemical data of the Bombouaka/Gambaga Group of the NE Voltaian Basin, Ghana to decipher the source of the sediments. Field measurements covered the Tossiegou, Poubogou, and Panabako Formations of the Bombouaka/Gambaga Group. The influence of hydraulic sorting was interpreted from the effects of highly resistant heavy minerals (identified in the petrographic studies) from polycyclic sources. Principal component analysis (PCA) was applied to the geochemical data to understand element associations. Two broad facies types were identified; lithofacies and ichnofacies. The lithofacies were observed as (a) asymmetric ripple marks on sandstones, (b) parallel lamination on silty/argillaceous sediments, (c) straight-crested and bifurcated ripples on shales, (d) flute casts and climbing ripples on sandy shales, (e) bipolar herringbone cross-bedding on quartz-rich sandstones, and (f) wavy lamination and cross-bedding on feldspathic sandstones. However, the ichnofacies include only Skolithos on quartzitic sandstones. The structural analyses suggest that about 85% of the paleocurrents were from NE to SW direction with subordinate directions from WNW to ESE. Based on the predominant paleocurrent directions, the sediments were probably derived from the basement Birimian rocks (metavolcanic and metasedimentary rocks with associated granitoids), previously paleogeographically located in the Amazonian Craton but now eroded, transported and transformed into the Birimian Supergroup from which the Voltaian sediments were derived. The PCA points to similar sources of granitoids and metasedimentary rocks. Therefore, the geochemical results and the PCA interpretations support the paleocurrent structures-inferred sources of the sediments in the NE Voltaian Basin.

Linking geology to the prevalence of non-communicable diseases: a case study of the Voltaian sedimentary basin, Ghana

“…The elemental association in cluster 2 are elements Voltaian sedimentary basin that are well known largely within mafic and ultramafic rocks except for K 2 O and its weathered clay products. Furthermore, the As association with this suite of elements indicates that it may be sourced from metamorphosed mafic-ultramafic suite of rocks, this would appear to support the widely held assertion that the sandstones from the area are partly derived from clastic sediments of the Paleoproterozoic Birimian basement metasedimentary rocks which underlies the Volta basin (Anani, 1999;Couëffé and Vecoli, 2011;Anani et al, 2017;Abu et al, 2020). PCA was carried out using SPSS version 20.0; the eigenvalues and rotated sum of squares loadings are shown in Table 3.…”

An overview of the geology of Tanga onshore basin: implication for hydrocarbon potential, Tanzania, East Africa

“…5). The Umba river sediment are the initial strata starting with coarse materials, high energy deposits very shorter time, deposited during glacial time (Abu 2018;Abu et al 2020), this interpretation Rop et al (2016) interpretation of a regional glaciation in the East Africa Rift System (EARS). This is also the lower part of the lower Tanga beds, following the sandstones or conglomeratic sandstone towards the mudstone in the river, are the fine layered siltstones which later moved into the middle Karoo beds.…”

“…The presence of marble limestone at the basement of Karoo and Tanga basin suggests that these carbonate rocks have experience some level of metamorphism (Nédélec et al 2007). The carbonates are at around the Umba River, overlain by conglomeratic sandstones; these sandstones are both silicified with the presence of quartz overgrowth (Anani et al 2017;Abu et al 2020) and unsilicified. These conglomeratic sandstones ( Fig.…”

“…3g). The quartzitic sandstones have indication of silicification via some level of metasomatism, indicating a level of compositional maturity while the feldspathic sandstones are poorly sorted with the presence of labile minerals feldspars indicating low level of reworking or alteration via diagenesis (Anani et al 2017;Abu et al 2020), although clay minerals from the alteration of feldspars could reduce the porosity of sandstones (Berger et al 2009;Dowey et al 2012Dowey et al , 2017a; Waldmann and Gaupp 2016), transpressional stress which are reported for the whole of the EARS (Rop et al 2016) structures like faults of joints could as well enhance the porosity of these sandstones. The arenaceous sediments, defining the top most part of the basin, are a mixture of fine, medium and coarse textured detritus.…”

“…These chemical sediments consisting of dolomitic marbles and dolomitic limestones formed in a deep marine environment, although carbonate materials could be detrital, this at Tanga basin are without sedimentary structures to support their detrital status (Pettijohn 1975), this can, however, be investigated further. The argillaceous facies immediately follows the carbonates also in a quite water environment and by a low energy water medium (Abu 2018;Abu et al 2020) of oxygen poor environment. The presence of dropstones observed in some exposures supports a glacial depositional environment where regression and transgression action of water (Trompette et al 1998;Klein and Ladeira 2004) would have controlled this group of facies, and this is part of the larger arenaceous facies class.…”