Petrographical, mineralogical, and geochemical characteristics of the Palaeocene lateritic bauxite deposits of Kachchh Basin, Western India

Abstract

Petrographical, mineralogical, and geochemical characteristics of a blanket‐type lateritic bauxite deposit, bordering the Deccan basalt in Kachchh, are investigated to interpret the parent rock, lateritization processes, and palaeogeographical position of the basin. The presence of partly weathered vesicular basalt at the base of the succession along with partly preserved plagioclase, augite, and hornblende in petrographical observations suggests the in situ nature of these bauxites. X‐ray diffraction analysis reveals gibbsite as the major bauxitic mineral associated with kaolinite, goethite, titanium‐rich anatase, calcite, haematite, and quartz as subconstituents. The presence of gibbsite, kaolinite, and goethite in the majority suggests that warm and humid climatic conditions prevailed during the lateritic bauxite formation. SEM‐EDS analysis shows that most of the gibbsites are mesocrystalline with particle sizes 50–200 μm that coexists with microcrystalline goethite, kaolinite, rutile, and haematite. These deposits are classified as bauxite, ferruginous bauxite, and laterite, based on chemical composition. The high CIA values (86.6–98.1%) suggest their formation under high run‐off and water‐logged conditions similar to that which prevails in the equatorial region. The Zr–Cr–Ga ternary plot testifies to the mafic composition of the parent rock. The major oxides and chondrite‐normalized trace and REEs behaviours, (La/Sm)N ratio (~5.77), and Eu anomaly of these lateritic bauxites suggest that they (bauxites) were formed in situ by the intensive leaching and alteration of the basaltic parent rock, and the process of bauxitization followed the path of deferruginization and destruction of kaolinite. The development of a lateritic regolith over the Deccan basalt was possible during Palaeocene time when the Indian Plate was in complete isolation and the Kachchh region was positioned near the equator in the Southern Hemisphere.

Role of cementation and compaction in controlling the reservoir quality of the Middle to Late Jurassic Sandstones, Jara dome, Kachchh Basin, western India

“…Dissolution by carbonate cement have generated secondary type intra‐particle porosity (Figure 8d), and found associated with authigenic cement and kaolinite formed through replacement of feldspar. Some grains demonstrate a reddish‐brown precipitate along the cleavage planes of weathered feldspar owing to secondary precipitation of iron oxides during diagenesis (Figure 6d; e.g., Singh & Srivastava, 2019).…”

Geochemistry of Eocene to Pliocene strata of the Bengal Basin: Implications for provenance and erosion of the Himalaya

“…The REE patterns and Eu anomalies are widely used to discriminate mafic and felsic sources of sedimentary rocks (McLennan et al, 1993; Singh & Rajamani, 2001; Wang, Zhou, Yan, & Li, 2012). Mafic rocks generally have less fractionated chondrite‐normalized REE pattern with low (La/Yb) N ratios and little or no negative Europium anomalies, by contrast, felsic rocks show highly fractionated chondrite‐normalized REE patterns with higher (La/Yb)N ratios and prominent negative Eu anomalies (Singh & Srivastava, 2019; Taylor & McLennan, 1985). All samples in this study show similar sub‐parallel and highly fractionated chondrite‐normalized REE patterns with (La/Yb) N ratios ranging from 7.11 to 11.87 and moderate negative Eu anomalies (Eu/Eu* = 0.57–0.73; Figure 4c), which suggests that sediments of the Bengal Basin are most likely derived from a felsic source.…”

“…Geochemical and petrographical compositions of clastic sedimentary rocks are widely used to determine the provenance, weathering of the source, and sedimentary processes (Bhatia, 1985; Bhatia & Crook, 1986; Fedo, Wayne Nesbitt, & Young, 1995; Fralick & Kronberg, 1997; McLennan, 1993; McLennan, Hemming, McDaniel, & Hanson, 1993; Nesbitt & Young, 1982; Patra, Singh, & Srivastava, 2014; Singh, 2009, 2010; Srivastava, Singh, & Patra, 2018; Taylor & McLennan, 1985). Particularly, immobile major and trace elements, such as Al, Fe, Th, Sc, Zr, and the rare earth elements (REE), have been widely considered as useful indicators for provenances owing to their resistance to weathering and alteration processes (Bhatia, 1985; Bhatia & Crook, 1986; Fedo et al, 1995; Fralick & Kronberg, 1997; Singh & Srivastava, 2019; Taylor & McLennan, 1985).…”

Provenance, tectonic setting, and source area weathering of Middle Jurassic siliciclastic rocks of Chari Formation, Jumara Dome, Kachchh Basin, Western India: Sedimentological, mineralogical, and geochemical constraints

“…The provenance of clastic sedimentary rocks can be determined by using petrography, including examining the undulosity and polycrystallinity of quartz grains (Basu, Young, Suttner, James, & Mack, ; Young, ), feldspar types (Pittman, ), lithic fragments (Pettijohn et al, ), and heavy mineral types (Asiedu, Suzui, & Shibata, ; Morton, ; Patra et al, ; Singh & Srivastava, ; Srivastava et al, ). The dominance of monocrystalline quartz grain suggests derivation of sediments from a granitic source (Basu et al, ).…”

“…The petrography and geochemistry of clastic sedimentary rocks provide valuable information for understanding the tectonic setting, provenance, paleoweathering, paleoclimate, and furthermore, paleogeographic reconstruction of sedimentary basins (Armstrong‐Altrin et al, ; Bhatia & Crook, ; Cullers, ; McLennan, Taylor, & Eriksson, ; Quasim, Khan, & Ahmad, ; Singh & Srivastava, ; Verma & Armstrong‐Altrin, ). The geochemical and mineralogical compositions of clastic sedimentary rocks are governed by several factors such as provenance, weathering, transportation, paleoenvironment, and diagenesis (Cullers, ; Ghosh, Sarkar, & Ghosh, ; Pettijohn, Potter, & Siever, ; Taylor & McLennan, ).…”