Pawan Kumar Rajak, Angana Chaudhuri, Naraga Prabhakar,Santanu Banerjee

Department of Earth Sciences, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India

Abstract Based on integration of field,petrographic and heavy mineral chemical data,this study highlights the source and tectonic setting of the Mesozoic sandstones of Kutch,Saurashtra,Narmada and Cambay basins at the western margin of India, formed by the progressive splitting of the eastern Gondwanaland. The Kutch Basin is dominated by arkosic sandstone, whereas Saurashtra, Narmada and Cambay basins show the predominance of sub-arkose and sub-litharenite. The modal analyses of framework grains in Kutch sandstones indicate basement uplift and transitional continent settings. In contrast, the sandstones of Saurashtra, Narmada and Cambay basins bear imprints of recycled orogenic and craton interior belts.The presence of abraded and detrital quartz overgrowth and rounded zircons in most sandstones reveal the recycling of sediments in these basins.Tourmaline and rutile mineral compositions constrain the possible lithology of source rocks.The tourmaline mineral chemistry (Ca-Fetot-Mg plot) suggests the derivation of sediments from various sources,including Li-poor granitoids associated with pegmatites, aplites, Ca-poor metapelites, metapsammites and quartz-tourmaline-rich granitic rocks.The compositions of rutile grains(Cr vs.Nb plot)in sandstones indicate metapelitic sources. The gamut of all mineral chemical data supports the predominance of sediment sources from quartzo-feldspathic rocks with minor inputs from mafic rocks. Based on available paleocurrent data and correlation of source compositions, we infer that the Mesozoic sediments of Kutch, Saurashtra, Narmada and Cambay basins were primarily sourced by various lithologies of the Aravalli Craton.The Narmada Basin possibly received additional sediment input from the Bundelkhand Craton.

Keywords Mesozoic sandstones, Rift basins, Tourmaline chemistry, Rutile chemistry, Kutch Basin, Sau

1. Introduction

The compositional characteristics of framework grains in sandstones provide crucial information about the source rock composition, tectonic setting, paleoweathering and transportation conditions (Dickinson,1970, 1985; Dickinson and Suczek, 1979; Ingersoll and Suczek, 1979; Dickinson et al., 1983; Critelli and Le Pera, 1994; Critelli et al., 2003; Garzanti et al., 2008,2009; Armstrong-Altrin et al., 2012, 2015, 2017;Chaudhuri et al.,2018,2020a,b).Furthermore,compositions of heavy minerals, which are rare in detrital sediments, provide precise information about the potential source lithology (Mange and Wright, 2007; von Eynatten and Dunkl, 2012). The chemistry of heavy minerals is particularly useful to distinguish multiple sources of sediments(Henry and Guidotti,1985;Mange and Morton, 2007; Meinhold, 2010; Tolosana-Delgado et al., 2018; Chaudhuri et al., 2020d). For example,the mineral chemistry of detrital rutile is useful in predicting source areas with various metamorphic rocks(Zack et al., 2002, 2004b; Triebold et al., 2007, 2012;Meinhold, 2010). Similarly, the variation in tourmaline mineral chemistry helps in identifying complex source areas with a wide variety of igneous and metamorphic rocks, including aplite, pegmatite, granitoid, metapelite,metapsammite,metacarbonate and metapyroxenite (Henry and Guidotti, 1985; Henry and Dutrow,1992;Hawthorne and Dirlam,2011).

Fig. 1 Geological map showing studied Mesozoic outcrops (marked rectangles) in Kutch (K), Saurashtra (S), Cambay (C) and Narmada (N)basins in western India and relevant geological units (adapted from various sources including, Dasgupta et al., 1993; Biswas, 2005;Ramakrishnan and Vaidyanadhan, 2008). Sample locations are indicated numbers with solid circles (Kutch Basin: 1. Zara, 2. Palara, 3.Gangeshwar, 4. Tapkeshwar, 5. Habo, 6. Bhuj; Saurashtra Basin: 1. Jhariya Mahadev Temple, 2. Thangadh, 3. Ranipat, 4. Dhrangadhra, 5.Surajdeval, 6. Wadhwan, 7. Surendranagar; Cambay Basin: 1. Himmatnagar and 2. Bhavpur; Narmada Basin: 1. Rampur, 2. Raisinghpur, 3.Bagh, 4. Man River).

Fig.2 Tectonic setting of the western continental margin of India with major tectonic trend of major rift basins(after Biswas,1987,1999).Note that the outcrops of the Mesozoic basins are extensively covered by Deccan flood basalt and Tertiary sediments.

The Late Triassic to Early Jurassic Gondwanaland breakup resulted in the initiation of several pericontinental rift basins at the western continental margin of India(Norton and Sclater,1979;Biswas,1982,1987).The characteristic expressions of Gondwanaland breakup are represented by the formation of Kutch,Saurashtra,Narmada and Cambay basins,which evolved temporally at the same time(Figs.1 and 2;Biswas,1982,1987, 1999). Several authors have investigated the exposures of these interlinked basins for sedimentological and paleontological attributes(Sahni,1936;Mukherjee,1983; Acharyya and Lahiri, 1991; Aslam, 1991; Akhtar et al., 1991; Arora et al., 2015; Mandal et al., 2016;Bhatt et al., 2016; Racey et al., 2016). Recent studies have provided multi-proxy data regarding the source of Mesozoic sediments and tectonic settings of the Kutch Basin (Chaudhuri et al., 2018, 2020a,b,c,d). Although basic sedimentological data are available for the Cambay, Saurashtra and Narmada basins (Akhtar and Ahmad,1991;Akhtar et al.,1994;Ahmad et al.,2014),a comprehensive provenance analysis is yet to be carried out.A comparative study of the source rocksiscrucial for illustrating the temporal evolution of these interlinked basins during the sequential break-up of Gondwanaland.The Cambay Basin is a prolific hydrocarbon-producing basin,although exposures are minimal,while the Kutch Basin has produced hydrocarbons in recent times. A detailed provenance analysis is also helpful for the characterization of hydrocarbon reservoir rocks of these Mesozoic basins.The objective of this study is to establish the source rock and paleotectonic setting of the interlinked Mesozoic riftogenic basins of western India.Furthermore,the source rock of the well-characterized Kutch Basin is correlated with those of other basins.We have examined selected sandstone samples for petrography, modal analysis and heavy mineral compositions and integrated these results to extract the potential source and tectonic evolution of these basins.

2. Geological and tectonic background

Kutch, Saurashtra, Narmada and Cambay basins were formed as interlinked rift basins at the western margin of India by the splitting of Gondwanaland during Mesozoic time (Fig. 1). The separation of India from Africa in the Jurassic and subsequent drifting of Madagascar and Seychelles from the eastern Gondwanaland during the Late Cretaceous formed a series of interlinked rifts basin at the western margin of India(Biswas, 1999; Chatterjee et al., 2013). Kutch, Saurashtra,Narmada and Cambay basins follow the major Precambrian tectonic trends viz. Delhi, Aravalli, Satpura and Dharwar trend, respectively (Biswas, 1987)(Fig. 2). The Kutch Basin was the first to originate by rifting during the Late Triassic, followed by the Saurashtra and Cambay basins in Early Cretaceous, and the Narmada Basin in the Late Cretaceous (Biswas,1987). The adjacent Saurashtra Basin, formed along the southwestward trend of the Aravalli trend, was separated from the Kutch Basin by Saurashtra upliftment during the Late Cretaceous and the rifting was aborted in the Kutch Basin (Biswas, 1999; Fig. 2). The NNW—SSE trending Cambay rift formed along the Dharwar trend during the Late Cretaceous. The basin was extended southward into the Gulf of Cambay. Its western margin was marked by the Saurashtra horst,which separated this basin from the Kutch Basin. The marine Cretaceous was extended up to the Jaisalmer—Barmer Basin to the north (Dolson et al.,2015; Beaumont et al., 2018). The ENE—WSW tending Narmada Basin, bounded by a system of subparallel faults, was formed by the reactivation along the preexisting Narmada-Son transform fault during the Late Cretaceous(Biswas,1987,1999;Tripathi,2006;Racey et al.,2016).The Narmada rift intersects the Cambay rift at the Gulf of Cambay. The extension of the Narmada graben in the continental shelf south of Saurashtra Basin is called Surat Basin. The Mesozoic sediment cover in Kutch and Saurashtra basins exceeds a few km(Acharyya and Lahiri,1991),whereas those in Narmada and Cambay basins are considerably thin.However,the Cenozoic succession of the Cambay Basin is substantially thicker than other basins.

The Kutch Basin exhibits several uplifts and faults. These are Nagar Parkar Uplift, Island Belt Uplift, Wagad Uplift and Kutch Mainland Uplift,associated with the Nagar Parkar Fault, Island Belt Fault, South Wagad Fault and Kutch Mainland Fault,respectively (Biswas, 1977, 2005, 2016). The oldest Jhurio Formation, resting unconformably on the Precambrian basement, comprises carbonate—shale associations intercalated with oolitic limestones(Table 1, Fig. 3A). The overlying fossiliferous Jhumara Formation comprises laminated shale,marl,siltstone and limestone with golden oolite and olivegreen shale. A thick coarsening-upward fossiliferous succession, consisting of calcareous sandstone and shale alternations, represents the overlying Jhuran Formation. The youngest Bhuj Formation consists primarily of sandstone and shale, kaolinitic claystone, glauconitic sandstone with abundant fossils(Fig. 4A). The sedimentary structures in the Jhuran and Bhuj formations indicate a southwesterly paleocurrent direction(Biswas,1987,1999,2005;Mandal et al., 2016; Arora, 2017; Desai and Biswas, 2018;Chaudhuri et al., 2020b). The sedimentary succession was deposited predominantly in a shallow marine environment with a gradual shift to a fluviodeltaic environment in the younger Bhuj Formation(Fürsich et al., 1992, 2001; Mandal et al., 2016;Bansal et al., 2017).

The Saurashtra Basin occurs to the south of Saurashtra horst, hosting Jurassic to recent sediments,covered by Deccan basalts (Biswas, 1987). The 600-meter thick, gently dipping (4°—8°) Mesozoicsuccession of the Saurashtra Basin is comprised of sandstone, siltstone, shale and coal with conglomerate, known as the Dhrangadhra Group. The Dhrangadhra Group is made up of four formations,viz.Than,Surajdeval,Ranipat and Wadhwan, in ascending order of succession (Table 1, Fig. 3B). The coarseningupward Than Formation is composed of medium- to fine-grained sandstone, carbonaceous shale and coal with wavy laminated sandstone and siltstone beds.The overlying Surajdeval Formation consists of medium-to fine-grained sandstone interbedded with shale and mudstone.The Ranipat Formation consists of a finingupward sequence dominated by cross-stratified sandstone and carbonaceous shale and mudstone with local conglomerate interbeds (Fig. 4B). The Wadhwan Formation consists of coarse- to medium-grained sandstone of estuarine to fluvial origin (Casshyap and Aslam, 1992; Khan et al., 2017). The Wadhwan Formation of the Dhrangadhra Group contains megaflora Onychiopsis and Weichselia of lower Cretaceous(Wealden) age and palynoflora Appendicisporites and Impardecispora of Aptian age(Singh and Venkatachala,1988).

Table 1 Lithostratigraphic subdivision of the Mesozoic sedimentary rocks of the Kutch Basin(adapted from Biswas,1977,1982);Saurashtra Basin(adapted from Casshyap and Aslam,1992;Khan et al.,2017);Narmada Basin(adapted from Tripathi,2006)and Cambay Basin(adapted from Bhatt et al., 2016).

Fig. 3 A) Field photograph showing alternating layers of shale and sandstone within the Cretaceous Bhuj Formation of Kutch Basin at Zara area(man in a red circle as a scale,height=172 cm);B)Cross-stratified sandstone beds within the Lower Ranipat Formation of Dhrangadhra Group in the Saurashtra Basin at Jharia Mahadev temple (hammer as a scale, hammer length = 38 cm); C) Vertical section across the Nimar Sandstone of the Narmada Basin at Gayatri mandir, Bagh area (man in a red circle as a scale, height = 168 cm); D) Alternating sequence of sandstone and siltstone layers of the Lower Member of Cretaceous Himmatnagar Sandstone Formation of Cambay Basin at Hathmati River section, Himmatnagar (man in a red circle as a scale, height = 170 cm).

The Upper Cretaceous sediments in the Narmada Basin make up the Bagh Group, which is a mixed carbonate—siliciclastic association (Tandon, 2000;Kumari et al., 2020; Keller et al., 2021). The Bagh Group consists of Nimar Sandstone, Nodular Limestone, and Coralline Limestone formations in ascending order of succession (Table 1, Figs. 3C and 4C; Bansal et al., 2020). Recent biostratigraphic data constrain Cenomanian, Turonian, and Coniacian ages for the Nimar, Nodular Limestone, and Coralline Limestone formations,respectively(Jaitly and Ajane,2013; Kumar et al., 2018). The Cretaceous Nimar Sandstone unconformably overlies the Precambrian Aravalli Supergroup and it consists of conglomerate,sandstone and mudstone with rare shale of fluvialmarine origin (Tripathi, 2006; Racey et al., 2016).The Nodular Limestone consists of an alternation of marly shale and biomicritic limestone showing nodular characteristics.Coralline Limestone consists of crossbedded limestone with an oyster-rich bed.The Nimar Sandstone is, overall, fining upward and consists of five different fluvio-marine facies associations(Bhattacharya et al., 2020).

Fig.4 Generalized lithologs of(A)Kutch,(B)Saurashtra,(C)Narmada,and(D)Cambay basins(Stratigraphic and paleocurrent data are from the following:Kutch Basin—Biswas,2005;Fürsich et al.,2005;Mandal et al.,2016;Saurashtra Basin—Casshyap and Aslam,1992;Narmada Basin — Acharyya and Lahiri, 1991; Cambay Basin — Ahmad and Akhtar, 1990; Aquil, 1982).

The NNW—SSE trending Cambay rift occurs between the Saurashtra horst and Aravalli range. In the Cambay Basin,the best exposure of the Himmatnagar Sandstone Formation occurs on the banks of the river Hathmati near Himmatnagar. The ～75 m thick Himmatnagar Sandstone Formation consists of conglomerate, sandstone, siltstone and shale (Table 1,Fig. 3D). At the southwestern part of the study area,Deccan basalts and recent alluvium overlie the outcrops of the Himmatnagar Sandstone,whereas,at the northeastern corner, it overlies the Precambrian Idar Granite (Choudhary et al., 1984). Bhatt et al. (2016)divided the Himmatnagar Formation into two stratigraphic members, viz. Lower and Upper (Table 1).The Lower Member consists of massive and crossstratified sandstone, siltstone and shale with plant fossils and trace fossils (Fig. 4D). The Upper Member of the Formation is composed of gritty-cobbly sandstone and trough cross-stratified sandstone with fossil wood showing paleocurrents towards the south and south-west. The Lower and Upper members of the Formation crop out towards northeastern and northwestern sides of the Himmatnagar town, respectively. This Formation is equivalent to the Nimar Formation of the Narmada Basin. It is contemporaneous with the Wadhwan Formation and Bhuj Formation in the Saurashtra and Kutch basins,respectively (Table 2) (Acharyya and Lahiri, 1991).The Himmatnagar Sandstone and Dhrangadhra Group contain upper Gondwana megaflora Weichselia and Onychiopsis, suggesting a Lower Cretaceous (Wealden) age (Sahni, 1936). Furthermore, theHimmatnagar Sandstone shows Appendicispotites and Impardecispora palynoflora of Aptian age (Acharyya and Lahiri, 1991).

Table 2 Comparison of Mesozoic succession and paleogeography of Kutch,Saurashtra,Narmada and Cambay basins(compiled from Biswas and Deshpande,1983;Biswas,2005;Fürsich et al.,2005;Dolson et al.,2015;Pandey and Pooniya 2015;Racey et al.2016;Alberti et al.,2017; Dasgupta,2021).

3. Methodology

Field investigations were carried out in selected sections to gather basic sedimentological information,including the thickness of formations and lithological variations(Fig.3,Table 1).Composite graphic logs were prepared for all four basins showing basic sedimentological data(Fig.4).From the Kutch Basin,33 sandstone samples belonging to Jhurio,Jhumara,Jhuran and Bhuj formations were collected from Zara, Palara, Bhuj,Habo, Gangeshwar and Tapkeshwar (Fig. 1, Table 3).Ten sandstone samples of the Dhrangadhra Group of theSaurashtra Basin were collected from Surendranagar,Wadhwan, Thangadh, Surajdeval, Ranipat, Dhrangadhra,Jharia Mahadev(Fig.1,Table 3).Eight samples of the Nimar Sandstone of the Narmada Basin were collected from the Man River, Raisinghpura, Rampura and Bagh in the Dhar district of Madhya Pradesh(Fig.1,Table 3). Ten samples of the Himmatnagar Sandstone were collected from Himmatnagar,Dhundhor,Bhavpur and Vantada (Fig. 1, Table 3). Thin sections of sandstones were prepared using Buehler?Epothin 2 Epoxy hardener and Buehler?Epothin 2 Epoxy resin at a ratio of 1:3. Each thin section was further polished using silicon carbide powders (80 μm, 220 μm, 400 μm,600 μm, 800 μm, 1000 μm, 3 μm, 1 μm, 0.3 μm). The petrographic observation was carried out using the Leica DM 4500P polarizing microscope attached with the Leica DFC420 camera using Leica Image Analysis software (LAS-v4.6) at the Department of Earth Sciences, Indian Institute of Technology (IIT) Bombay.Point counting of sandstone samples was carried out following the Gazzi-Dickinson method (cf. Ingersoll et al., 1984). For each thin section, more than 300 framework grains were counted to determine the variation in the sandstone composition derived from different provenance terrain with the help of Folk(1974) sandstone classification scheme and tectonic setting discriminant plot of Dickinson et al.(1983).

Table 3 GPS data of the sampled location of different basins.

The sandstone samples containing a sufficient amount of heavy minerals were selected for the mineral analysis.Nine samples of Kutch Basin,five samples of Saurashtra Basin,five samples of Narmada Basin and three samples of Cambay Basin were used for heavy mineral separation. Sandstone samples were pulverized using an agate mortar and then sieved for the 63—125 μm size fraction. By panning underwater, the heavy minerals were separated from this size fraction.The heavy mineral concentrates were then mounted on glass slides with the mixture of Beuhler?epothin 2 epoxy hardener and Beuhler? epothin 2 epoxy resin.The slides were kept to air-dry for 24 hours followed by oven-dry for 24 hours at 50°C.Mineral compositions of heavy minerals were analyzed using a Cameca SX Five Electron Probe Micro Analyzer (EPMA) at the Department of Earth Sciences,IIT Bombay.The details of the analytical procedure for EPMA mineral analysis are summarized in Chaudhuri et al. (2020d).

Fig.5 Cross-polarized(A—E)and plane-polarized(F)photomicrographs showing textural characteristics of sandstones of Kutch Basin.Arkosic sandstone with A)carbonate cement(yellow arrow)in Jhuran Formation from Palara section;B)plagioclase feldspar(yellow arrow)and porefilling carbonate cement (red arrow) in Bhuj Formation from Bhuj section; C) rock fragment in Jhuran Formation showing tectonic fabric(yellow arrow); and D) rutile (yellow arrow) in the Jhuran Formation and zircon (red arrow) from Zara section, and E—F) garnet grain (red arrow) in the Jhuran Formation from Tapkeshwar section.

4. Results

4.1. Petrography of sandstones

The Mesozoic sandstones in the Kutch Basin are predominantly medium- to fine-grained, moderately sorted arkoses with sub-angular to sub-rounded framework grains. The sandstones in the youngest Bhuj Formation are relatively coarser and are poorly sorted than other Formations. Quartz grains are dominantly monocrystalline,with a few grains showing undulose extinction. Polycrystalline quartz grains showing tectonic fabric are rare (Fig. 5C) (e.g.,Ingersoll and Suczek 1979; Tortosa et al., 1991). Kfeldspars are dominant, but plagioclase feldspars are also found in all the studied sandstones (Fig. 5B).Overgrowths on quartz grains are commonly abraded.The pore spaces in these sandstones are filled with carbonate and ferruginous cement (Fig. 5B). Rhombohedral dolomitic cement is common in sandstones of the Bhuj Formation (Fig. 5B). Feldspar grains in sandstones are occasionally replaced by carbonate cement along grain boundaries and cleavage planes.The common heavy minerals in these sandstones are zircon,tourmaline,rutile,garnet and opaques(Fig.5D and E). The average composition of the Mesozoic sandstone of Kutch is Q52F47R1(Supplementary Data 1).In the QFR plot(Folk,1974),most of these sandstones occupy the field of arkose,with a few data plotting in the subarkose field (Fig. 10A). In the QFL plot(Dickinson et al.,1983),the majority of the sandstones indicate transitional continental setting, with a few data indicating basement uplift provenance(Fig.10B).

Fig.6 Cross-polarized photomicrographs of Dharangadhara sandstones showing A)coarse-grained,ferruginous-coated framework grains with carbonate cement (red arrow), chert grains (green arrow) and polycrystalline quartz (yellow arrow) at the Gaushala road of Ranipat Formation; B) Surajdeval Formation showing siliceous cement (red arrow) and muscovite (yellow arrow) from Songadh section; C) Ranipat Formation are medium-grained sandstones with orthoclase feldspar (yellow arrow) at Kaplidhar section; D) Than Formation contains metamorphic rock fragments(yellow arrow)at Thangadh area;E)plagioclase feldspar(yellow arrow)in sandstone of Ranipat Formation from Gaushala road, and F) rutile grains (yellow arrow) in calcareous sandstone of Wadhwan Formation at Baghela.

Fig. 7 Cross-polarized photomicrographs of Cretaceous Nimar Sandstone showing A) Gayatri mandir, Bagh area sandstones are mediumgrained calcareous sandstones with rounded zircon (red arrow) at the lower; B) medium-grained sandstone with rounded chert (yellow arrow) at the upper part; C) Rampur sandstone section showing microcline (yellow arrow); D) abraded quartz overgrowth (yellow arrow) in the Raisinghpur sandstone section; E) Man river section showing moderately sorted sandstone with brown tourmaline (red arrow) and F)rounded polycrystalline quartz grain with tectonic fabric (yellow arrow).

The Dhrangadhra Group is made up of fine- to coarse-grained(Fig.6A),poorly to moderately sorted,angular to subrounded grains of quartz, feldspar and rock fragments. Quartz content in the sandstone is～85% by volume with minor feldspar (4% by volume)and rock fragments(11%by volume).Quartz grains are predominantly monocrystalline, showing undulatory extinction (Fig. 6C). Although orthoclase is the common feldspar (Fig. 6C), plagioclase (Fig. 6E) and microcline are also found. The mica is a muscovite type (Fig. 6B). Rock fragments include polycrystalline quartz (Fig. 6A), chert (Fig. 6A) and gneissic rock fragments (Fig. 6D). The formation is dominated by silica cement (Fig. 6B) with subordinate iron oxide(Fig. 6E) and calcite cement (Fig. 6A and F). Silica cement mostly occupies the intragranular pore spaces but also occurs as overgrowths. The heavy minerals in the formation include zircon, tourmaline, rutile,garnet, ilmenite, monazite and opaques. Sandstones of the Dhrangadhra Group occupy the fields of sublitharenite in the QFR plot of Folk (1974) (Fig. 10A).The average composition of the sandstone is Q85F4R11.The QFL(Dickinson et al.,1983)data occupy recycled orogen field with a few data points in the field for craton interior (Fig. 10B).

The framework grains of the Nimar Sandstone are medium- to fine-grained, rounded to subangular and moderately to well sorted. The sandstone contains quartz, feldspar, rock fragments, mica and heavy minerals. Quartz (79% by volume) grains are dominantly monocrystalline, showing undulatory extinction. The feldspar (9% by volume) is dominated by microcline with subordinate orthoclase and rare plagioclase(Fig.7C).Lithic fragments(12%by volume)are mainly chert,polycrystalline quartz(Fig.7B and F)and metamorphic gneiss. Mica belongs to the muscovite type. The sandstone is cemented mainly by calcite, quartz and iron oxide (Fig. 7A and D). Quartz cement occurs as overgrowths. Abraded quartz overgrowth is present in the Nimar Sandstone(Fig.7D).The heavy minerals include zircon, tourmaline, rutile,apatite and opaques (Fig. 7A and E). QFR data of the Nimar Sandstone occupy the fields of sub-arkose and sub-litharenite in the plot of Folk (1974), with the majority of sandstone containing 75% to 85% quartz grains (Fig. 10A). The average composition of the sandstone is Q79F9R12.The QFL data of sandstones plot within recycled orogen field (Dickinson et al., 1983)(Fig. 10B).

Fig. 8 Photomicrographs of Lower Member of Himmatnagar Sandstone of Cambay Basin showing A) angular to subangular, medium-sized quartz grains with green and yellow tourmaline (red arrow) and orthoclase (green arrow) at the Hathmati river section, the coarsegrained sandstone variety showing B) subangular to subrounded, moderately sorted grains from Vantada village section; C) Bhavpur sandstone thin section showing detrital quartz overgrowth(yellow arrow)and zircon(red arrow);D)metamorphic rock fragments,(yellow arrow),sedimentary rock fragments(red arrow)and polycrystalline quartz(green arrow)from Dhundhor village;E)sedimentary rock fragments from Dhundhor section(yellow arrow)and F)cluster of zircon grains at the Bhavpur village section(yellow arrow)(A in plane-polarized light,B—F under crossed-polars).

Sandstone in the Himmatnagar Formation is medium- to coarse-grained (Fig. 8B), poorly to moderately sorted, consisting of sub-angular to subrounded grains of quartz and feldspar (Fig. 8A). Quartz grains predominate (86% by volume) the sandstone, with minor feldspar, rock fragment, mica and heavy mineral. Quartz is predominantly monocrystalline,showing undulatory extinction. Detrital quartz overgrowth is common in the Himmatnagar Sandstone(Fig.8C).Although orthoclase is the common feldspar(Fig. 8A), occasionally plagioclase and microcline are found. Both biotite and muscovite occur in the sandstone,but muscovite is a common type of mica present in the sandstone. The rock fragments include chert,gneiss and polycrystalline quartz showing distinct metamorphic fabric (Fig. 8D). The formation is dominated by chalcedony cement (Fig. 8C) with subordinate ferruginous cement. Chalcedony cement mostly occupies the intragranular pore spaces(Fig. 7E). Rounded zircon and detrital quartz overgrowth are common(Fig.8C and F).Sandstones occupy the fields of sub-arkose and sub-litharenite in the QFR plot of Folk(1974)(Fig.10A).The average composition of the Himmatnagar Sandstone is Q86F6R9. The QFL data of sandstones plot within the craton interior and recycled orogen fields (Dickinson et al., 1983)(Fig. 10B).

Fig. 9 Photomicrographs under the polarizing microscope showing zircon, rutile, tourmaline, apatite and staurolite grains from Kutch,Saurashtra,Narmada and Cambay basins(Kutch Basin-zircon(A),rutile(B)and tourmaline(C);Saurashtra Basin-apatite(D),zircon(E),rutile(F) and tourmaline (G); Narmada basin-apatite (H), zircon (I), rutile (J) and tourmaline (K and L); Cambay Basin-staurolite (M), zircon (N),rutile (O) and tourmaline (P).

Fig. 10 A) QFR diagram of Folk (1974) and B) QFL tectonic setting diagram of Dickinson et al. (1983) showing sandstone data of Kutch,Saurashtra, Narmada, and Cambay basins [For QFR, total Q = Qm + Qp(2—3) + Qp(＞3), Total F = K + P + M and Total R = Lv + Ls + Lm + Chert + Qp(＞10) and QFL, Q = Qm + Qp(2—3) + Qp(＞3) + Chert + Quartzite, F = K + P + M and L = Lv + Ls + Lm. Where Q = Quartz, Qm = Monocrystalline quartz, Qp = Polycrystalline quartz; F = Feldspar, K = Orthoclase, P = Plagioclase and M = Microcline; L/R = Lithic/Rock fragments, Lv = Volcanic lithic fragments, Ls = Sedimentary lithic Fragments, Lm = Metamorphic lithic fragments].

4.2. Heavy mineral study

Zircon, rutile, tourmaline, garnet and monazite occur as predominant heavy minerals within the sandstones of the Kutch Basin. Sub-rounded to rounded zircon grains appear colourless to pale pink,with a few grainsshowing brown colour(Fig.9A).Tourmaline grains are dominantly sub-angular to sub-rounded and appear greenish-brown to bluish-green (Fig.9C).Rutile grains with sub-angular to sub-rounded morphologies show a reddish-brown to amber-brown appearance(Fig.9B).

Fig.11 Concentrations of Cr and Nb in rutiles of Mesozoic sandstones.Cr vs Nb source rock discrimination plot(Triebold et al.,2012)of A)Kutch, B) Saurashtra, C) Narmada and D) Cambay basins. While the Saurashtra Basin is dominated by only metapelitic sources, the Kutch,Narmada and Cambay basins show dominance of a metapelitic source with minor metamafic input.

Fig. 12 The ternary Ca-Fetot-Mg plot (molecular proportion) (Henry and Guidotti, 1985) showing source rock characteristics of tourmalines from the A) Kutch, B) Saurashtra, C) Narmada and D) Cambay basins. A total of 227 tourmaline grains from all these basins were analyzed,with one measurement per grain. The numbered fields in the ternary Ca-Fetot-Mg plot represent different rock types: (1) Li-rich granitoid pegmatites and aplites, (2) Li-poor granitoids and associated pegmatites and aplites, (3) Ca-rich metapelites, metapsammites and calcsilicate rocks, (4) Ca-poor metapelites, metapsammites and quartz-tourmaline rocks, (5) Metacarbonates, and (6) Metaultramafics.

Heavy minerals of the Dhrangadhra Group in the Saurashtra Basin include tourmaline, rutile, zircon,opaques, monazite, apatite and staurolite. Zircon grains are colourless to pale pink (Fig. 9E). The shape of zircon varies from elongated, rounded to subrounded and prismatic. Tourmaline is green, yellow and brown with angular to subrounded shapes(Fig. 9G). Rutile grains are red to light brown, exhibiting elongated to subrounded shapes (Fig. 9E). The apatite grains are elongated and colourless(Fig. 9D).

Heavy minerals in the Nimar Sandstone in the Narmada Basin include tourmaline, rutile, zircon,ilmenite,apatite,opaques and monazite.Zircon grains are colourless,light yellow and light blue(Fig.9I).The shape of the zircon grain varies from rounded to subrounded, prismatic and elongated. Tourmaline grains show yellow, brown, green, and blue colours with shapes varying shapes(Fig.9K and L).Rutile grains are red to deep red and are angular to subrounded(Fig. 9J). A few grains of apatite (Fig. 9H) and monazite are found in sandstones.

The most common heavy minerals in the sandstones of the Himmatnagar Formation in Cambay Basin are tourmaline, zircon, rutile, ilmenite, opaques,staurolite and monazite.Zircon grains are sub-rounded to rounded and are generally colourless to light blue(Fig. 9N). Tourmaline grains are yellow and green and are sub-rounded to prismatic (Fig. 9P). The deep red rutile grains show sub-angular to sub-rounded shapes(Fig. 9O). Staurolite shows angular to subangular shapes and is generally colourless (Fig. 9M).

4.2.1. Rutile mineral chemistry

A total of 113 rutile grains in sandstones of Kutch,Saurashtra,Narmada and Cambay basins were analyzed(Supplementary Data 2).The average(of 38 grains)TiO2content of rutile in Kutch sandstone is 98.30 wt%.The average(of 25 grains)TiO2content of rutile in the Saurashtra Basin is 98.77 wt%. The Cr content of the majority of the rutile grains remains within 2000 ppm,whereas the Nb content of rutile varies from 500 to 5000 ppm. The average Cr and Nb concentrations of rutile grains in the Kutch Basin are 1161 and 2127 ppm,respectively (Fig. 11A). Cr and Nd concentrations of rutile grains in Saurashtra sandstones are 1204 ppm and 2172 ppm,respectively(Fig.11B).Although the average(of 26 grains)TiO2content of rutile grains in the Nimar Sandstone (98.78 wt%)is similar to those of Kutch and Saurashtra sandstones. The average concentrations of Cr and Nb elements in Nimar sandstones are 1526 ppm and 1818 ppm,respectively(Fig.11C).The average TiO2content of 24 grains of rutile in the Cambay Basin is 97.54 wt%. Cr and Nb concentrations in the rutile are 1884 and 1296 ppm, respectively (Fig. 11D). The relationship between Cr and Nb reveals a metapelitic origin for the majority of rutile grains for all basins(Fig. 11A—D). A few rutile grains, however, show a metamafic origin.

4.2.2. Tourmaline mineral chemistry

A total of 227 tourmaline grains were analyzed in sandstones of Kutch,Saurashtra,Narmada and Cambay basins(Supplementary Data 3).Schorl and dravite are the most common varieties of tourmaline. In the Ca-Fetotal-Mg plot (cf. Henry and Guidotti, 1985), the majority of data plot at the bottom part of the triangular diagram, covering both Fe and Mg ends. The average FeO,MgO and CaO contents of tourmalines of Kutch sandstones are 7.56, 4.91 and 0.65 wt%,respectively.The Ca-Fetot-Mg plot(Fig.12A)indicates the derivation of tourmaline grains primarily from type-4 (Ca-poor metapelites, metapsammites and quartz-tourmaline) and type-2 (Li-poor granitoids,pegmatites and aplites) fields with minor inputs from type-3(Ca-rich metapelites,metapsammites and calcsilicates) field. The average FeO, MgO and CaO contents of tourmalines of Dharangadhara sandstones are 8.54, 5.95 and 0.93 wt%, respectively. The Ca-Fetotal-Mg plot data of tourmalines plot exclusively within type-4 field (Fig. 12B). The average contents of FeO,MgO and CaO in the tourmaline of Nimar Sandstone are 10.78,3.83 and 0.60 wt%,respectively.The tourmaline data plots in equal proportions within type-2 and type-4 fields(Fig.12C). The FeO,MgO and CaO contents of tourmaline in the Himmatnagar Sandstone are 9.09,5.76 and 0.85 wt%,respectively.Most data plot within the type-4 field while a few data occupy type-2 and type-3 fields (Fig. 12D).

5. Discussion

5.1. Source implications of major minerals in sandstones

Sandstones of the Saurashtra Basin are primarily sublitharenite with minor quartz arenite, whereas sandstones of the Narmada and Cambay basins are classified as sublitharenite and subarkose (Fig. 10A).However, the sandstones of the Kutch Basin are predominantly of arkosic type with minor subarkose(Fig. 10A). Sandstones show a predominance of monocrystalline quartz with a minor proportion of polycrystalline quartz grains. The monocrystalline quartz grains in these basins are possibly derived from a granitic source(cf.Basu et al.,1975).Polycrystalline quartz grains consist either of a few subgrains with straight to slightly curved boundaries or a large number of elongated crystals, exhibiting irregular to serrated grain boundaries (Figs. 6A, 7F and 8D). The first type of polycrystalline quartz indicates its derivation from plutonic igneous rocks(Blatt and Christie,1963; Folk, 1974; Blatt et al., 1980), whereas the second type of polycrystalline quartz suggests a metamorphic origin (Blatt et al., 1980). Hence, the nature of quartz grains demonstrates their derivation from a wide variety of igneous and metamorphic sources. The content of feldspar is highest within the sandstones of Kutch. The abundance of feldspar is controlled by two factors — a) the transport distance of sediments from source to sink and/or b) the presence of local feldspathic source rocks (Dickinson and Suczek, 1979). The sandstones in all four basins indicate the dominance of felsic composition in source rocks. The abundance of feldspars in the Kutch Basin possibly corresponds to the orthoclase-rich, syenitic basement rocks in the source (Biswas and Deshpande,1968). The presence of angular rutile grains and rounded tourmaline minerals suggests the derivation of sediments from both nearby and long-distance sources, indicating multiple sources. Rounded zircons and abraded overgrowth of quartz grains in the Kutch,Saurashtra, Narmada and Cambay basins suggest a polycyclic origin of the sediments (Figs. 7A, D, 8C, F and 9A) (Pettijohn et al., 1987; Zuffa, 1987). The paleocurrent data of fluvial sandstones in the Kutch,Saurashtra, Narmada and Cambay basins infer an overall southwesterly paleoslope (Fig. 2; see also Aquil, 1982; Biswas, 1987; Ahmad and Akhtar, 1990;Casshyap and Aslam, 1992; Bhatt et al., 2016; Mandal et al.,2016;Arora,2017;Khan et al.,2017;Chaudhuri et al.,2020b).Therefore,sediments in these Mesozoic basins were mostly derived from common source rocks.

5.2. Rutile and tourmaline chemistry for source characterization

Rutile grains are commonly identified in medium-to high-grade metamorphic rocks and as well as in siliciclastic sedimentary rocks(Force,1980,1991).Because of high mechanical and chemical stability, it is one of the significant heavy minerals for provenance studies(Morton and Hallsworth,1999).The contents of Cr and Nb in rutile distinguish between metamafics and metapelites source lithologies (Zack et al., 2002, 2004b;Triebold et al.,2007,2012;Meinhold et al.,2008).The average TiO2content of rutile in all basins is broadly similar. The majority of rutile grains in these basins derive from metapelitic source rocks (Fig. 11A—D).Rutile mineral data reveals minor inputs of sediments from metamafic sources in the Kutch, Saurashtra and Narmada basins.Although Cr and Nb contents of rutiles of Mesozoic sandstones broadly overlap,Narmada data show a distinct cluster showing an intermediate Nb and intermediate to high Cr concentrations.

Tourmaline compositions are characterized by the range of elbaite-schorl and schorl-dravite/uvite solid solution series (von Eynatten and Gaupp, 1999). The composition of tourmaline varies widely based on the nature of source rocks. The Ca-Fetotal-Mg plot shows the compositional variation of tourmalines about their source rocks (Henry and Guidotti, 1985). The Ca-rich tourmalines, that originated from Li-rich granitoid,pegmatite and aplite,are classified as type-1.The Ferich tourmaline grains, classified as type 2, typically occur in Li-poor granitoid, pegmatite and aplite. The Ca-rich tourmalines in metapelites, metapsammites and calc-silicates are considered as type-3.The type-4 tourmaline is Mg-rich, occurring in Ca-poor metapelites, metapsammites and quartz-tourmaline rocks.Types 5 and 6 tourmalines are usually observed in metacarbonates and metapyroxenites,respectively.

The Ca-Fetotal-Mg plot suggests the derivation of tourmaline in the Mesozoic sandstones from Ca-poor sources (Fig. 12). Tourmalines in the Kutch, Narmada and Cambay basins are primarily derived from Li-poor sources (Fig. 12A, C and D) with a minor contribution from Ca-rich source rocks (Fig. 12A and D). Rutile chemistry shows the dominance of metapelitic signatures in the Kutch, Saurashtra, Narmada and Cambay basins (Fig. 11). Tourmalines in Saurashtra sandstone correspond to Ca-poor metapelites, metapsammites and quartz-tourmaline source rocks. Kutch and Cambay basins show minor contributions of tourmaline grains from Ca-dominated metapelites, metapsammites and calc-silicates rocks (Fig. 12A and D).The rutile and tourmaline mineral chemistry results are consistent with the petrographic observations,indicating multiple sediment sources for the Mesozoic basins. Although previous studies indicated multiple sediment sources for the Mesozoic sandstones of Kutch(Chaudhuri et al.,2018,2020a,b,c,2021),the present investigation demonstrates variable sediment sources for Mesozoic sandstones in four Mesozoic basins in western India.

5.3. Paleotectonics

The QFL triangular plot of Dickinson et al. (1983)distinguishes between various tectonic settings.Quartzose sandstones retain the dominant craton interior signature due to the long-distance transportation and weathering, sourced by granitoid and gneiss (Dickinson and Suczek, 1979). The quartzofeldspathic sandstone indicates transitional continental signatures due to the mixing of sediments from stable craton interior and uplifted basement rocks(Dickinson and Suczek, 1979). The sandstones of the Kutch Basin indicate the predominance of transitional continental provenance, with signatures of the uplifted basement in the older Mesozoic (Fig. 10A and B;see also Chaudhuri et al., 2018). The whole-rock geochemistry of shales in the Kutch Basin further supports the passive continental margin setting(Chaudhuri et al., 2020a). Sandstones of Saurashtra,Narmada and Cambay basins show the predominant sediment inputs from a recycled orogeny (Fig. 10).However, a few data of Saurashtra and Cambay sandstones suggest a craton interior setting (Fig. 10A and B). Lithic fragments (chert, gneissic rocks and polycrystalline quartz), abraded quartz overgrowths and rounded zircons are common in these basins.The high lithic content in sandstones relates to local sediment inputs,possibly from rift shoulders.As vast areas of the outcrop are covered by Deccan Traps and Holocene sediments,it is difficult to differentiate the sources of lithics (Fig. 2).

5.4. Inferred sources for Mesozoic sandstones

The disintegration of India from Gondwanaland turned the craton-margin rifts into passive margins as the Indian plate took a northward drift.Sedimentation took place in shallow marine settings in the Mesozoic interlinked basins during the Jurassic and Cretaceous periods.The Narmada Basin was the last to form at the western margin of India during the Late Cretaceous period (Fig. 2; Tandon, 2000; Kumari et al., 2020;Keller et al., 2021).

Owing to the southwesterly paleoslope of the Kutch, Saurashtra and Narmada basins, the sediments were derived primarily from source rocks occurring to the northeast of the study area. The Cambay Basin,formed at the eastern margin of both basins during the Early Cretaceous. Although the initial subsidence of the Cambay Basin was slow, it subsided rapidly during the Cenozoic time. During this time, the Narmada Basin was extended up to the central part of the Indian Craton.The Aravalli highlands,comprising igneous and metamorphic rocks of felsic and mafic composition,lied to the north and northeast of these basins.Paleoto Mesoproterozoic metasediments of the Aravalli Supergroup and Meso- to Neoproterozoic Delhi Supergroup, along with Neoproterozoic Erinpura Granite,Malani igneous suites, Idar Granite, constituted the Aravalli-Delhi fold belt(Figs.1 and 2)(Crawford,1975;Trivedi et al.,1987;Gupta et al.,1997;Roy and Jakhar,2002; Sinha-Roy et al., 2013). The Bundelkhand Craton,located to the east of the study area,consists of Bundelkhand massif, Bijawar Group of rocks, Gwalior Group of rocks and Vindhyan sediments. The Bundelkhand massif is composed of Mesoarchean Bundelkhand Gneissic Complex (BnGC) with Tonalite—Trondhjemite—Granodiorites (TTG), Neoarchean volcano-sedimentary rocks of the Greenstone belt,Neoarchean granites, Proterozoic quartz reefs and mafic dykes (Sharma, 2000; Rao et al., 2005;Bhattacharya and Singh,2013;Singh and Divedi,2015).The Vindhyan Supergroup, located to the east of the study area, predominantly comprises calcareous,arenaceous and argillaceous sediments, and overlies the BnGC in the SE, S and SW regions. The Lower Proterozoic Gwalior Group, consisting of shales, sandstones, cherts, conglomerates and grits, occurs towards the northwest of the BnGC. The Bijawar Group,to the south of Bundelkhand craton,comprises sandstone, shale, dolomite, chert, conglomerate,breccia, volcanic traps, phosphorite and quartzite(Kumar et al., 1990).

The basin architecture and tectonics control the sedimentation history and geotectonic evolution of the studied basins with geological time (Biswas, 1982,1987). Extensive study of Mesozoic Kutch Basin sediments revealed several possible source rocks,including banded gneissic complex, Aravalli and Delhi supergroups, Nagar-Parkar igneous suite and Malani igneous suite (Chaudhuri et al., 2018, 2020a,b,c,d). Detrital geochronology of zircon and monazite suggests the dominance of source rocks equivalent to the Pan-African Orogeny(Chaudhuri et al.,2020b).The paucity of outcrops related to the Pan-African Orogeny could be attributed to the extensive cover of Deccan volcanic rocks(Fig.1,Chaudhuri et al., 2020b). The Saurashtra Basin formed on the continuity of the Aravalli trend and possibly received sediments from source rocks similar to Kutch Basin.The Kutch and Saurashtra basins could have formed a thick pile of sediments until Early Cretaceous time. The Saurashtra Basin was uplifted during the Upper Cretaceous and the Cambay Basin came into existence (Hardas, 1980; Biswas, 1987). The NNW—SSE oriented Cambay Basin, sloping towards the south,formed during the Early Cretaceous, which separated the Kutch-Saurashtra basins from the Aravallis(Fig.2).The fluvial sandstones of the Cambay Basin are correlatable with Lower Cretaceous fluvio-deltaic deposits of Kutch-Saurashtra,implying possible cross-trends across the Cambay Basin (Biswas, 1987). Sedimentation took place in the Narmada Basin during the Late Cretaceous due to the subsidence of the Narmada graben.The Kutch and Cambay basins witnessed a period of non-deposition and Deccan volcanism during this time. The west to west-southwestward paleoslope of the Narmada Basin indicates sediment supply from both east and north.

The Aravalli—Delhi fold belt contributed major sediment supply to the Kutch,Saurashtra and Cambay basins (Fig. 2). Rutile and tourmaline chemistry bear imprints of metapelitic sources in sandstones of the Kutch, Saurashtra, Narmada and Cambay basins.Mineral chemical data of Nimar sandstones in the Narmada Basin are unlike Aravalli metapelities, suggesting derivation of major sediment input from Bundelkhand Craton besides minor inputs from the Aravalli Craton.

In summary, the comparative provenance study of these Mesozoic basins identifies the banded gneissic complex, Aravalli and Delhi supergroups as the major sediment contributors for Kutch, Saurashtra and Cambay basins. The Narmada Basin received sediments primarily from Bundelkhand Craton, Bijawar,Gwalior Group and Vindhyan Supergroup, with minor inputs from Aravalli and Delhi supergroups.

6. Conclusions

1) The petrography and heavy mineral chemistry of the sandstones belonging to the interlinked Kutch, Saurashtra,Narmada and Cambay basins at the western margin of India indicate multiple source rocks,dominated by felsic rocks. The texture of heavy minerals bears a recycled nature of sediments.

2) Rutile mineral chemical data indicate the predominance of metapelitic source rocks in the Kutch,Saurashtra, Narmada and Cambay basins.

3) The mineral chemical data of tourmaline points to the predominance of Ca-poor metapelites, metapsammites and quartz-tourmaline sources in all four basins. Li-poor granitic source rocks are envisaged as an additional source for the Kutch,Narmada and Cambay basins.

4) The Kutch Basin received sediments dominantly from a transitional continental tectonic setting. In contrast, the Saurashtra, Narmada and Cambay basins were dominated by sediments derived from a recycled orogeny, with minor craton interior tectonic settings during the Jurassic to Cretaceous period.

5) The present study established multiple igneous and metamorphic source rocks for four Mesozoic basins in western and northwestern India.Banded gneissic complex, Aravalli and Delhi supergroups supplied sediments to the Kutch as well as Saurashtra and Cambay basins. However, the Narmada Basin received the majority of its sediments from Bundelkhand Craton, Bijawar Group and Vindhyan Supergroup, with a minor contribution from Aravalli and Delhi supergroups.

Conflicts of interest

The authors declare that there is no conflict of interest.

Acknowledgements

The authors are pleased to the Indian Institute of Technology Bombay for infrastructure facilities. The authors are also thankful to S.C. Patel and Javed M.Shaikh for providing analytical support at the DST-IITB National facility for EPMA, Department of Earth Sciences,Indian Institute of Technology Bombay.Authors thank Indian Institute of Technology Bombay for the financial support(RI/0220-1000613-001) to SB.