Provenance and weathering history of Archaean Naharmagra quartzite of Aravalli craton, NW Indian shield: Petrographic and geochemical evidence

Abstract

The petrography as well as major, trace and rare earth element (REE) compositions of Mesoarchaean Naharmagra quartzite of Aravalli Craton have been investigated to determine influence of sorting and recycling, source area weathering and provenance composition. The quartzites are mineralogically mature, medium to coarse grained quartz arenite with minor medium grained arkose. Petrographic analysis revealed that the quartzites were primarily derived from granite and metamorphic basement rocks of typical cratonic interior. All samples have SiO 2 /Al 2 O 3 > 10 (average ~31), which indicates high maturity consistent with petrographical results. Quartzites are depleted in many major and trace elements due to quartz dilution. Many of the samples have undergone postdepositional K metasomatism. The calculated premetasomatic CIA values (46-92) indicate highly variable degree of source weathering compatible with non-steady state weathering. CIA and PIA values in combination with petrographic evidence favour intense chemical weathering probably under warm and humid climate. Provenance modeling indicates that the quartzites can be best modeled with a mixture having 50% tonalite-trondhjemite-granodiorite, 40% granite and 10% basalt. Probably, the sedimentation of these rocks took place in a stable and young cratonic basin evolved through accretion and tectonic amalgamation of pre-existing continental arcs comprising TTG and granitic bodies.Keywords: geochemistry, crustal evolution, Aravalli craton, Rajasthan, Indian shield greenstone tectonics and the upper crust was predominantly mafic in composition. Condie (1993Condie ( , 1997 suggested that upper crustal geochemical changes at APT can be related to four evolutionary changes of earth history i.e., (i) komatiite effect, (ii) tonalite-trondhjemitegranodiorite (TTG) effect, (iii) subduction effect, and (iv) weathering effect. The komatiite effect is preserved in the sedimentary rock records in terms of high Ni-Cr contents, flat REE patterns and no Eu-anomaly in Archaean sedimentary rocks. The sedimentary rocks derived from TTG sources will display highly fractionated REE patterns with high (La/Yb)n ratios and Y depletion. The subduction effect is preserved in terms of less fractionated REE patterns and less depleted large ion lithophile elements (LILE) in comparison to TTG derived sediments. Some geochemical changes across APT may be related to palaeoweathering effects, since in some cases the intensity of chemical weathering decreased during postArchaean period. Therefore, the geochemistry of clastic sedimentary rocks is particularly helpful in constraining the crustal evolution during Archaean (McLennan et al.,

Geochemistry of Mesoproterozoic sedimentary rocks of upper Vindhyan Group, southeastern Rajasthan and implications for weathering history, composition and tectonic setting of continental crust in the northern part of Indian shield

“…Although, TTG is an important component of Archaean gneissic terrains through out the world the granitoids of BGC have more similarities with the less common low-Al 2 O 3 Archaean granite (Ahmad and Tarney, 1994) of Condie (1993). However, the geochemical characteristics of Archaean Naharmagra quartzite of the BGC indicate the presence of TTG in their source (Raza et al, 2010a). Therefore, the BGC components such as Granitic gneisses, TTG, mafic enclaves and late Archaean Berach Granite (Sivaraman and Oden, 1982), probably supplied the debris for the Kaimur Sandstone.…”

“…International rock standards were analyzed along with upper Vindhyan samples. The data on these standers are comparable with those recommended and the precision is better than 10% RSD (Raza et al, 2010a). The petrology of sandstones was determined using Gazzi-Dickinson point counting method (Dickinson, 1970;Ingersoll et al, 1984).…”

“…The significance of sediment geochemistry in determining the palaeoclimatic conditions, provenance characteristics and basinal tectonic setting is well established in literature (Bhatia, 1983;Taylor and McLennan, 1985;Jahn and Condie, 1994;Roser and Korsch, 1986;Hofmann, 2005;Osae et al, 2006;Roddaz et al, 2006;Absar et al, 2009;Raza et al, 2010aRaza et al, ,b, 2011. Although, various aspects of Vindhyan basin and its succession have been studied for a long time, little attention has been paid to geochemistry of sedimentary rocks.…”

Petrology and geochemistry of greywackes of the ~1.6 Ga Middle Aravalli Supergroup, northwest India: evidence for active margin processes

“…Taylor and McLennan 1985;Tran et al 2003;Raza et al 2010b;Fatima and Khan 2012;Wang et al 2012;many others). The data of MAGs are plotted in various diagrams involving these element pairs, along with various possible basement end members and idealized source components for comparison (Figure 8).…”

Geochemical, Sr and Nd isotopic studies on the Kalva Rangan Durga Quartzites of the Shimoga greenstone belt: Implications on weathering of Dharwarian continental crust

“…Older sedimentary rocks are enriched in Mg, Fe, Al, Cr, and Ni, while younger sedimentary formations are enriched in Na, K, Rb, and Sr. REE, U, and Th abundances of these two types also show significant differences. Based on the elemental abundances data, the authors suggested that the older belts were developed in shallow water basins on a mafic rock‐dominated crust and the younger belts were laid down in rifted basins on a sialic basement (Raza et al, ).…”