Neoarchaean Dongargarh Rapakivi A-type Granites and its Relationship to Pitepani Tholeiites

Special Volume No.16, 2014, pp. 25-40

Gondwana Geological MagazineGGM

www.ggsnagpur.org

Neoarchaean Dongargarh Rapakivi A-type Granites and its Relationship to Pitepani Tholeiites

1 2 1 1Deepanker Asthana *, Anil M. Pophare , S. Rajalingam and Harshvardhan Kumar

1 Department of Applied Geology, Indian School of Mines, Dhanbad-826004, India2Department of Geology, RTM Nagpur University, Nagpur-440001, India

*E-mail: [email protected]

Abstract

Keywords: Dongargarh batholiths, A-type granites, Pitepani tholeiites, Extreme differentiation, Slab retreat, Trace element modelling.

The Neoarchaean Dongargarh mobile belt of central India is characterised by the Dongargarh batholith, an older Nandgaon bimodal

volcanic suite and younger Khairagarh volcano-sedimentary sequence. The Dongargarh batholiths are disparate bodies of granites. The most

widespread facies of Dongargarh granites are represented by the A-type granites, which occasionally show Rapakivi texture. The Pitepani

tholeiites and Bijli rhyolites of the Nandgaon bimodal volcanic suite are spatially and temporally associated with the A-type Dongargarh

granites. Extreme differentiation of a relatively primitive and crustally contaminated evolved Pitepani tholeiites followed by mixing, reproduces

almost all the major geochemical features of the Dongargarh A-type granites as well as their rapakivi textures. The Pitepani tholeiites represent

asthenospheric decompression melting and associated lithospheric extension in response to slab retreat and accordingly the Dongargarh A-type

granites represent extreme differentiation of Pitepani tholeiites in a hot and rifting lithosphere in response to slab retreat. The model is

compatible with field relationships, independently corroborated by the A2 character of these granites, that supports and validates the original

chrono-stratigraphy of the Dongargarh Supergroup as described by Sarkar (1957, 1958, 1994).

Introduction

Granites and their volcanic counterparts represent the most abundant constituents of the Bastar craton (Fig. 1a). Therefore, in order to unravel the crustal evolution processes in central India it is critically important to understand the petrogenesis of granites and their relationship to mantle derived magmas, if any. However, prior to ascertain the various processes involved in granite formation, it is imperative to first classify various types of granites. Over the past several decades, approximately 20 different schemes have been proposed to classify granites (e.g., Barkar et al., 1975; Barbarin, 1999; Frost et al., 2001). In spite of their shortcomings, the classification of granites into I-type, S-type, M-type and A-type (Frost et al., 2001; Kemp et al., 2007), represents the most popular, simple and widely used classification scheme of granites (e.g., Bonin, 2007). In general, A-type granites are anhydrous and considered to be derived from relatively dry and hotter magmas, compared to I and S-type granites, and emplaced in intra-plate or in an anorogenic tectonic environment (Loiselle and Wones, 1979;

Frost and Frost, 1997). However, these are also found in close association with continental growth processes in extensional accretionary orogens (e.g., Zhao et al., 2008; Chen et al., 2009; Kemp et al., 2009). The A-type granites are chemically distinct from the more common I- and S-types granites, implying different modes of formation, the exact form of which are subjects of considerable debate (Bonin, 2007). The majority of the models proposed for the formation of A-type granites fall into two broad categories: (i) extreme crystal fractionation (~ 90%) of tholeiitic mafic suites (Loiselle and Wones, 1979; Turner et al., 1992; Frost and Frost, 1997; Vander Auwera et al., 2003), and (ii) shallow level melting of calc-alkaline rocks (Patiño Douce and Beard, 1995; Patiño Douce, 1997) or partial melting of ancient lower crust (Jiang et al., 2009), especially partial melting of felsic granulites from which a melt component has already been extracted (Whalen et al., 1987; King et al., 1997). Partial melting of tonalite-trondjhemite-granodiorite (TTG) suite, including charnockite has also been proposed as a source of the A-type granites (Landenberger and Collins, 1996; Zhao et al., 2008). In view of the wide spectrum of A-type magmas ranging from metaluminous to

Deepanker Asthana et al.

peraluminous to peralkalic, a single petrogenetic model is unlikely to account for all the A-type granites. At the same time, several complex processes that includes a combination of crustal and mantle sources may have also given rise to A-type granites (e.g., Yang et al., 2006).

Fractionation of I and S-type granites cannot produce A-type granites, since crystal fractionation accompanies cooling and the temperatures of both I and S-type granites are lower than that of A-type granites. However, extreme crystal fractionation of mafic to intermediate tholeiitic magmas has been shown to be a viable mechanism for the formation of A-type granites, especially when these are spatially and temporarily related to each other (e.g., Turner et al., 1992; Frost and Frost, 1997; Vander Auwera et al., 2003).

A-type granites, often with rapakivi textures are the most widespread facies of the Dongargarh plutons (Narayana et al., 2000). This paper describes the geochemical characteristics of A-type Dongargarh granites and presents a petrogenetic model for their formation via extreme crystal fractionation of variably crustally contaminated Pitepani tholeiites and mixing. This simple model explains both the field association and geochemistry of the Dongargarh A-type granites and also accounts for the formation of rapakivi textures.

Geological Framework

The Bastar craton of central India is an important cratonic nuclei of the Archaean global record (Radhakrishna and Naqvi, 1986; Bleeker, 2003). It is bounded by ENE-WSW trending Central Indian Tectonic Zone (CITZ) towards the north, Mahanadi and Godavari grabens towards north-east and south-west, respectively and Eastern Ghats Mobile Belt towards the south-east. The N-S trending Neoarchaean/ Palaeoproterozoic collage of mobile belts along with batholithic granitoids, termed the Kotri-Dongargarh Mobile Belt (KDMB) geographically corresponds with the Kotri lineament, a deep crustal dislocation in the Bastar craton (Rajurkar et al., 1990). The northern most part of the KDMB is represented by Malanjkhand granitoids and Dongargarh Supergroup and extends for over 400km along Kotri lineament towards south (Ramakrishnan and Vaidyanadhan, 2008). In Bastar craton, the Neoarchean-Palaeoproterozoic Dongargarh Supergroup represents an important mobile belt along the N-S-trending Kotri lineament (Fig.1a) towards the north. It is ~12km thick, ~100km wide, and extends for ~300km along the Kotri lineament. Origin of Dongargarh Supergroup is a significant and long standing issue in central India (Sarkar, 1957; Yedekar et al., 1990; Deshpande et al., 1990; Neogi et al., 1996; Asthana et al., 1996, 1997, 2006; Sensarma et al., 2002, 2004; Sensarma and Mukhopadhyay, 2003; Sensarma, 2007). It has played a crucial role in formulating the currently popular and controversial tectonic model of central India (Yedekar et al., 1990) as well as the mantle plume related bi-modal Large Igneous Province (LIP) model (Sensarma, 2007).

The Dongargarh Supergroup is divided into lower Nandgaon Group comprising bimodal Bijili rhyolites and Pitepani volcanics and upper Khairagarh Group of volcano-sedimentary sequences (Sarkar, 1994) (Fig. 1b). The Pitepani volcanics are made up of a high-Ti tholeiitic suite and a low-Ti, high-Mg andesitic suite (Asthana et al., 2010, 2012). The Dongargarh granites have intruded into the Amgaon gneisses and the bimodal volcanic suite of Nandgaon Group. The Dongargarh granites are unconformably overlain by the Khairagarh Group. The Dongargarh granite represents one of the oldest rapakavi granite occurrences and comprises different batholiths and stocks stretching in N-S direction. It is exposed around Dongargarh, Amgaon, Deori and south of Bhandara-Rajnandgaon highway.

The Dongargarh granitic pluton comprises three distinct textural and compositional varieties of granites: i) Porphyritic granodiorite (PG), ii) Coarse equigranular granite (EG), and iii) Microgranite (MG) (Narayana et al., 2000). The PG are I-type adakitic granites (Asthana et al., 2010, 2012) and is intruded by the EG and basic dykes. The EG are A-type granites and represent the major facies of Dongargarh granites. The Dongargarh granite complex is devoid of pegmatites and contains rounded microgranular enclaves, syn-plutonic porphyritic dolerite dykes having feldspar phenocrysts and minor gabbro bodies. The Dongargarh coarse equigranular granite displays hypidiomorphic granular texture with pink K-feldspar (orthoclase-microperthite), plagioclase, smoky quartz, amphibole and biotite along with accessory ilmenite, sphene, magnetite, zircon, apatite and allanite (Narayana et al., 2000). Rapakavi textures are shown by sporadically developed plagioclase-mantled K-feldspar ovoids. Uranium mineralisation, concomitant shearing at the eastern margin of the batholith as well as fluorite mineralisation at Chandi- Dongri are considered to be related to the emplacement of Dongargarh pluton (Deshpande, 1984; Krishnamurthy et al., 1998b; Pandey et al., 1993).

The U-Pb zircon age of Dongargarh granites is 2432 ± 6 Ma (Ahmad et al., 2008), which is slightly younger as compared to the Bijli rhyolites that gave U-Pb zircon age of 2491± 28 Ma (our unpublished data). However, precise zircon dates and isotopic systematics of the various types of Dongargarh granites are not available. The Rb-Sr, Sm-Nd and Pb-Pb whole rock isotopic studies on the Dongargarh granites (Sarkar et al., 1981; Krishnamurthy et al., 1988a, 1990; Pandey et al., 1993) has given variable ages and initial isotopic ratios (2270 ± 90 Ma, Sr = 0.7092 ± 0.0054; 2462 ± 22 Ma, Sr i i

= 0.701 ± 0.00042; 2361 ± 114 Ma, initial åNd = -7.0 ± 1.4 and 2410 ± 29 Ma, Pb model µ of 8.86 ± 0.05) overlapping those of 1

Bijili rhyolites and Malanjkhand granodiorites.

Analytical Techniques

Given that all rocks in the Dongarharh volcanic province have suffered deformation and sub-greenschist to greenschist

26

facies of metamorphism, variable element mobility is a real possibility. In order to minimise the effects of these secondary processes, fresh and fine-grained Pitepani tholeiites were carefully selected from low strain zones, avoiding areas close to faults and areas containing multiple veins to minimise potential chemical re-equilibration of mobile elements in the field (Pophare, 2001). Samples devoid of secondary alteration features and with less than trace amounts of carbonate or

sulphide minerals under thin sections were selected for the present study. Whole rock XRF analyses and loss on ignition (LOI) data were used to screen fresh samples for detailed trace element analyses.

The geochemical analyses reported here were carried out at National Geophysical Research Institute, Hyderabad. Major elements were analysed by Phillips PW 1400 XRF for the Pitepani tholeiites. Reproducibility of the Phillips PW1400

Fig.1a. Geological division of central India into different blocks separated by lineaments/sutures.

Neoarchaean Dongargarh Rapakivi A-type Granites and its Relationship to Pitepani Tholeiites 27

analyses is ± 1% (Govil, 1985). Trace element analyses, that also includes REE and HFSE, for Pitepani tholeiites were analysed by ICP-MS (Plasmaquad PQ 1). Blanks and JB-2, JB-3 and JA-1 were analysed as unknown on routine basis. Accuracy and precision of the trace element analyses is better than ± 7% (Balaram, 1995). The analytical techniques and accuracy and precision of the Dongargarh granites are given by Narayana et al (2000).

Geochemical Signatures of A-type Granites

A number of discrimination diagrams have been proposed to distinguish A-type granites from other types of granites (Whalen et al., 1987; Frost et al., 2001). A-type granites are enriched in alkalis (K O + Na O), high field 2 2

strength elements (HFSE) Zr, Y, Nb, Ga and rare earth Telements (REE) (except Eu) and their FeO /MgO ratios are

higher in comparison to I-and S-type granites at SiO < 70 2 Twt%. High ratios of FeO /MgO, Ga/Al and Zr + Nb + Y + Ce

contents are considered to be most diagnostic features of A-type granites (Chappel and White, 1974; Whalen et al., 1987; Creaser et al., 1991; Frost et al., 2001; Yang et al., 2006; Jiang et al., 2009), although extensively fractionated I-type granites may be indistinguishable from A-type granites. On primitive mantle normalised plots, extensive crystal fractionation of feldspar and accessory phases in A-type granites are revealed by Ba, Nb, Sr, Eu, P and Ti negative anomalies. Overall, the geochemical characteristics of the A-type granites imply shallow-level crustal processes (< 1GPa, the absence of garnet and presence of plagioclase) of a relatively dry source at high

temperatures and extensive crystal fractionation of feldspar. The Dongargarh A-type granites have Y/Nb ratios > 1.2 that suggest a crustal affinity (Eby, 1990, 1992).

Geochemistry of the Dongargarh A-type Granites

Recently, Asthana et al. (2010, 2012) have identified four petrologically and geochemically distinct types of granites in the Dongargarh batholith viz.: I-type, A-type, S-type granites and leuco-granites. This paper deals exclusively with the petrology and geochemistry of the A-type granites and is based on the data of Dongargarh granites given by Narayana et al (2000). All samples designated as coarse equigranular granites (EG) plot in the field of granite, both in the feldspar triangle of O'Connor (1965) (Fig. 2a) and in the TAS diagram (Fig. 2b). In the TAS diagram, the granite samples straddle the boundary between alkaline to sub-alkaline fields, however in the SiO vs. Zr/TiO plot of Winchester and Floyd(1977) all the 2 2

samples plot only in the sub-alkaline field (Fig. 2c). In the QAP diagram of Streckeisen (1976) these samples plot in the monzo-granite to quartz-monzonite field (Fig. 2d). As per the classification scheme of Frost et al (2001), these are ferroan (Fig. 3a), while majority of the granites are metaluminous (Fig. 3b) and alkali-calcic (Fig. 3c), whereas few evolved samples are per-aluminous. However, a few lesser evolved samples are alkalic as well.

The Dongargarh granites are siliceous with SiO ranging 2

from 71.5 to ~ 75 wt% and are enriched in alkalis (K O = 4.4 to 2

5.6 wt%, Na O = 3.8 to 5.2 wt% and K O + Na O ≥ 9 wt%). 2 2 2TThese granites have low FeO (1.2 to 3.5 wt%), MnO (0.01 to

Fig.1b. Generalised geological map of the part of Dongargarh Supergroup (modified after Deshpande et al., 1990). WW- Chattishgarh Group, KK- Khairagarh Group, ++-Dongargarh Granite (A-type), MG- Leucogranite, PG- I-type adakitic granites, VV- Pitepani Volcanics, Bijili Rhyolite, AGN- Amgaon Gneisses. A- Amgaon, C- Chichola, CD- Chandan Dongri, D- Deori, DG- Dongargarh, R- Ratan Dongri.

Deepanker Asthana et al.28

Fig.2. (a) Ab-An-Or ternary plot (after O'Connor, 1965) showing granite field for the Dongargarh coarse equigranular granites (EG), (b) TAS classification (after Cox et al., 1979) showing sub-alkaline to weekly alkaline characteristics for the EG, (c) Zr/TiO -SiO plot (after Winchester and 2 2

Floyd, 1977) showing sub-alkaline character for EG and (d) QAP plot based on IUGS classification (after Streckeisen, 1976) indicating monzo-granite to quartz monzonite composition for EG.

Fig. 3. Binary diagram showing (a) Ferroan, (b) meta-aluminous to weekly per-aluminous and (c) alkali-calcic character of Dongargarh coarse equigranular granites (EG) (after Frost et al., 2001).

0.1wt%), CaO (0.6 to 1.1 wt%), P O (0.01 to 0.04 wt%) and 2 5# # MgO (0.14 to 0.44 wt%) contents. The Mg [Mg = molar

T T(MgO)/ (MgO + FeO )] varies from ~ 8 to ~ 40 and FeO /MgO ratios vary from ~ 3 to ~ 22.4 (Table 1); values higher compared to the average I-type and S-type granites (e.g., Chen et al., 2009).

The Dongargarh granites are characterised by elevated concentrations of HFSE (Nb > 15 ppm, Zr > 130 ppm, Y > 30

ppm), REE (total ÓREE 105 to 738 ppm, average ~358 ppm) (except Eu) and low concentrations of elements compatible in mafic silicates (Co, Sc, Cr, Ni) and feldspars (Al O , CaO, Ba, 2 3

Sr, Eu) that results in high Ga/Al ratios (10000*Ga/Al ranging Tfrom ~ 2.7 to ~ 3.2) and FeO /MgO ratios. Accordingly, the

granite samples fall in the field of A-type granites in all the discrimination diagrams of Whalen et al. (1987) (Fig. 4). Chondrite normalised REE patterns are LREE enriched


a) b) c)

Table 1: Major and trace element compositions of Dongargarh coarse equigranular granite (EG) and Pitepani tholeiites.

Dongargarh coarse equigranular granite (Rapakavi A-type granites) Pitepani tholeiites

Sample C 314 C 316 C317 C 327 MM 6 MM7 MM10 MM16 MM 27 MM126 MM 146-2 MM 147 AM-32 AM19

SiO 73.02 72.45 71.45 73.93 74.15 74.43 74.39 74.64 74.12 74.12 74.98 74.91 52.01 49.612

TiO 0.28 0.25 0.29 0.2 0.17 0.18 0.18 0.16 0.17 0.14 0.18 0.12 1.4 12

Al O 13.68 14.72 14.17 14.04 14.15 14.41 13.78 13.68 13.83 13.72 13.6 13.06 14.81 12.892 3

TFe O 3.13 2.88 3.55 2.13 1.96 1.53 2.07 1.96 2.07 1.88 2.14 1.18 13.5 16.942 3

MnO 0.02 0.1 0.02 0.09 0.07 0.09 0.06 0.11 0.01 0.03 0.1 0.07 0.22 0.25

MgO 0.14 0.16 0.17 0.15 0.44 0.15 0.18 0.14 0.13 0.18 0.14 0.39 5.17 7.25

CaO 0.91 0.9 1.1 0.8 0.8 0.78 0.82 0.8 0.75 0.71 0.8 0.59 7.98 9.09

K O 5.4 5.62 5.59 5.39 4.59 4.75 4.45 4.5 4.51 4.62 4.42 4.65 1.26 0.492

Na O 4.2 4.56 4.36 3.77 4.39 4.34 5.03 5.03 5.23 4.83 5.09 4.48 3.07 2.72

P2O 0.04 0.04 0.04 0.03 0.02 0.01 0.02 0.02 0.02 0.02 0.02 0.01 0.17 0.145

Cs 1.9 1 1.8 2.1 1.8 1 27 1.7 1.4 0.5 1.8 0.6 0.57 0.62

Rb 127 119 135 169 143 150 145 112 116 135 121 166 39.48 40

Ba 748 632 806 457 972 1020 1092 1069 1232 993 1159 9.3 227.3 196

Sr 80 70 85 58 65 63 64 68 63 47 67 38 308.98 176

Th 23.3 19.6 22.6 18.2 14.3 23 15 11 8.5 21.7 16.7 18.6 5.1 0.5

U 2.5 2.1 3.5 2.9 2.7 3.1 2.3 2.6 2.3 3.7 3.1 4.2 1.21 0.1

Zr 237 148 264 195 141 158 152 134 151 182 135 189 181 67

Hf 4.4 3.7 5 4.1 3.6 4.3 4.3 3.8 4.1 5.6 3.9 5.4 4.34 1.6

Y 45 33 50 47 43 44 44 39 40 49 46 48 38.27 27

Ta 1.4 1.8 1.6 1.6 1.8 2 1.5 1.5 1.5 1.9 1.7 1.7 0.49 0.28

Nb 28 28 36 27 17 17 17 15 15 19 16 16 8.39 4.86

Sc 4 5 4 2 3 2 3 3 3 2 3 2 41.24 42

V 1 21 0 0 1.2 1.3 1.4 0.9 0.7 3 1 0.4 351.02 272

Cr 1 5 3 0 0.4 1.6 0.7 0.6 0.3 1.2 0.7 0.9 121.22 161

Ni 2 4 2 2 3 2 3 2 2 2 2 2 59.02 75

Co 73 62 64 18 76 71 75 68 68 84 69 85 63.38 65

Cu 12 6 12 8 11 9 10 8 9 8 9 27 34.4 79

Zn 90 71 98 71 102 71 96 91 100 100 122 96 143.41 111

Ga 23 21 24 21 23 21 22 22 21 23 23 21 n.d n.d

La 197.62 133.54 180.73 104.41 53.11 74.55 70.63 34.93 12.66 63.678 42.72 67.28 23.7 5.68

Ce 350.94 225.59 321.36 189.46 102.26 133.9 130.5 70.55 31.55 119.36 89.43 125.03 50.28 13.93

Pr 29.04 19.78 27.14 15.97 12.91 15.66 15.72 9.49 5.32 14.78 12.08 15.12 6.37 2.2

Nd 114.15 68.01 110.6 65.27 46.2 49.2 53.31 34.5 23.34 49.12 44.18 50.13 27.02 11.35

Sm 14.51 9.99 14.59 10.5 9.94 9.14 9.58 8.13 6.58 9.56 9.47 9.38 5.63 3.67

Eu 1.3 1.57 1.34 0.83 1.3 1.16 1.48 1.39 1.56 1.3 1.57 1.2 1.56 1.18

Gd 10.14 9.87 10.45 8.15 6.99 7.23 7.77 6.43 6.2 7.45 7.78 7.71 5.9 4.01

Tb 1.48 1.16 1.71 1.38 1.21 1.28 1.27 1.13 1.15 1.34 1.32 1.32 n.d n.d

Dy 8.77 6.34 9.82 8.67 7.09 7.03 6.6 6.26 6.45 7.24 7.21 6.78 5.65 3.9

Ho 1.55 1.23 1.58 1.52 1.42 1.38 1.36 1.32 1.4 1.57 1.47 1.52 n.d n.d

Er 4.28 3.21 4.65 4.25 3.91 4.16 4.1 3.82 3.73 4.8 4.39 4.4 3.66 2.4

Tm 0.51 0.39 0.6 0.57 0.58 0.64 0.6 0.58 0.55 0.71 0.6 0.65 n.d n.d

Yb 3.48 2.47 4.21 3.88 3.96 3.9 4 3.56 3.6 4.92 4.17 4.2 3.46 2.06

Lu 0.52 0.41 0.56 0.48 0.61 0.59 0.57 0.58 0.5 0.72 0.6 0.62 0.52 0.36

å REE 738.29 483.56 689.34 415.34 251.49 309.82 307.49 182.67 104.59 286.55 226.99 295.34 133.75 50.74

Eu/Eu* 0.3109 0.4777 0.316 0.2643 0.4529 0.4214 0.5082 0.5677 0.7351 0.454 0.5427 0.4187 0.827 0.939

Mg# 8.1 9.9 8.7 12.2 30.8 16.3 14.7 12.4 11.1 15.9 11.5 39.6 24.37 26.48

n.d. - not determined

relative to HREE with (La/Yb) ratios varying from ~ 2.5 to ~ N

41, with strong negative Eu anomalies (Eu*/Eu = 0.26 to 0.74) (Fig. 5a). In primitive mantle normalised plots, the granites show negative anomalies of Ba, Sr, Zr, P, Ti and Eu, patterns typically associated with A-type granites (Wu et al., 2002) (Fig. 5b). The Na + K contents of these granites are more or less equal to Al and hence, these are aluminous A-type granites (King et al., 1997). Further, on the Y vs. Nb tectonic

discrimination diagrams of Pearce et al. (1984) these granites plot in the within-plate granite field (Fig. 6) and on the triangular diagrams of Y - Nb - Ce, Y - Nb - Zr/4 and Yb -Ta - Th/3 of Eby (1990, 1992) all the Dongargarh aluminous A-type granites plot in the A - type granites field (Fig. 7). Thus, it 2

can be said that the Dongargarh A-type granites were formed in an extensional subduction related environment (cf., Zhao et al., 2008; Chen et al., 2009).


Fig. 4. Discrimination diagrams (Whalen et al., 1987) showing A-type characteristics for Dongargarh coarse equigranular granite (EG).

Fig.5. (a) Chondrite normalised REE pattern in EG showing high total REE abundances, moderate to high fractionation and negative Eu anomaly. Normalising values are taken from Boynton (1984). (b) Primitive mantle normalized trace element pattern for EG displaying negative anomalies of Ba, Nb, Sr, P, Eu and Ti. Normalising values are from Sun and McDonough (1989).


a) b)

Fig.6.. Tectonic discrimination diagram (after Pearce et al., 1984) showing within-plate trend for Dongargarh A-type granites.

Fig.7. Representative triangular plots (after Eby, 1992) showing A2-type characters for Dongargarh A-type granites.

Petrogenesis of the Dongargarh A-type granites

The Dongargarh A-type granites show continuous variation in SiO from 71.5 to ~ 75 wt% and linear to slightly 2

Tcurvilinear trends on Harker diagrams for TiO , FeO , P O , 2 2 5

CaO and K O (Fig. 8), suggesting that all the samples are co-2

magmatic. These linear to slightly curvilinear trends may result from mixing processes between two or more components, from partial melting processes or from fractional crystallisation with or without assimilation. Simple mixing between two components produces linear correlations, which is not the case and also cannot account for the well developed negative anomalies for several elements that are present in the Primitive mantle normalised plots. Moreover, very good correlations are observed on plots of elements versus immobile and incompatible elements, that corroborates the co-genetic behaviour of Dongargarh A-type granites (Fig. 9).

The Dongargarh A-type granites formed under shallow crustal conditions, which is indicated by prominent negative Eu and Sr anomalies, along with high HREE contents and nearly flat HREE patterns, suggest presence of plagioclase and absence of garnet in the source (Watkins et al., 2007). Moreover, high HFSE and HREE contents imply their derivation from a relatively dry and pyroxene rich source (Whalen et al., 1987). Ultra high temperature (UHT) felsic granulites are present in central India. However, partial melting of felsic granulites, including granulites that had undergone a previous episode of melts extraction (e.g., Zhao et

Tal., 2008; Chen et al., 2009) cannot produce the extreme FeO / MgO ratios of the Dongargarh granites (e.g., Creaser et al., 1991). Moreover, lower crust and melt depleted granulites are too refractory and have positive Eu anomalies (Taylor and McLennan, 1985). Perhaps, the clinching evidence against a UHT felsic granulite source for the Dongargarh A-type


TFig. 8. Harker diagrams showing decreasing trends of P O , FeO , TiO , CaO and K O; correlated with crystallisation of accessory phases.2 5 2 2

granites is the marked difference in their ages, the former are not much older than 1.6 Ga. (Bhandari et al., 2010), whereas the granites are ~2.43 Ga old. Although, generation of meta-aluminous A-type granites through low-pressure melting of calc-alkaline granitoids (Patiño Douce, 1997) is another possibility, but this model is not viable since calc-alkaline granitoids are conspicuous by their absence from the Dongargarh Supergroup. In terms of field association, the possible source of the Dongargarh A-type granites includes partial melting of Dongargarh I-type adakitic granites and extreme crystal fractionation of the coeval and spatially

related Pitepani volcanics. However, the Pitepani high-Mg andesites and Dongargarh granites have very low HREE contents and contrast with the enriched HREE content of the Dongargarh A-type granites. Moreover, low pressure TTG melts are per-aluminous (Watkins et al., 2007), whereas majority of the Dongargarh A-type granites are meta-aluminous. The Bijli rhyolites have higher SiO contents and 2

therefore cannot be the source for these granites. Finally, the only viable mechanism for the generation of

Dongargarh A-type granites, on the basis of regional geology and field relationship, is extreme fractional crystallisation of


Fig. 9. La, vs. Ce, Sm, Gd, Pr and Nd plots showing linear trends indicative of samples belonging to same suite.

Pitepani tholeiites. This model is independently supported by the correlation of Eu anomalies with 'arc signatures' (i.e. Nb/La ratio) (Fig. 10) that indicates feldspar fractionation was coupled with generation of Dongargarh A-type granites. The REE (La/Yb), LREE (La/Sm), HREE (Gd/Yb) ratios and the negative Eu and 'arc signatures' (i.e. Nb/Ce, Nb/Th ratios) of the Dongargarh A-type granites, reveal hyperbolic mixing trends (Fig. 10). The two mixing end members have contrasting REE, LREE, HREE ratios and Eu and Nb anomalies, respectively. The first mixing end member, represented by Sample No. C-317 has well developed negative Eu and Nb anomalies and is LREE enriched, while the second mixing end member represented by Sample No. MM-27 has only minor Nb and Eu anomalies and almost flat REE pattern. Mixing of these two end members defines the overall REE patterns of the Dongargarh A-type granites (Fig. 11).

Compositions matching of the end members MM-27 and C-317 were derived by the extensive fractional crystallisation of two different samples of Pitepani tholeiites, i.e. AM-19 and AM-32, respectively. Sample No. AM-19 is a relatively primitive sample and show only mild REE enrichment, negligible Eu and Nb anomalies, whereas Sample No. AM-32 is a relatively evolved sample and has undergone

Fig. 11. Chondrite normalised REE plot and Primitive mantle normalized trace element plot showing containment of range of all samples by the two end members (i.e., MM-27 and C-314).


Fig. 10. (a) (La/Yb)n vs. (Nb/La)n, (b) (Nb/La)n vs. (Gd/Yb)n, (c) (Nb/La)n vs. (La/Sm)n plots showing hyperbolic trends indicative of mixing between two end members and (d) (Nb/La)n vs. Eu/Eu* plot indicative of feldspar fractionation.

extensive crustal contamination coupled with fractional crystallization as shown by well developed Eu and Nb negative anomalies as well as LREE enrichment (Pophare, 2001). The computer program, 'FC-AFC-FCA and Mixing modeller' of Ersoy and Helvaci (2009) was used to carry out

® © the modelling. This program is a Microsoft Excelspreadsheet program for modelling geochemical differentiation of magma by crystal fractionation, crustal assimilation and mixing. In modelling for trace elements and rare earth elements the equation for Rayleigh fractional crystallisation is used.

FC (D-1)C = C F l 0

Where, FC C - Concentration of an element in the remaining melt l

during fractional crystallisationC - Concentration of the trace element in parental 0

liquid (initial composition)

D - Bulk partition coefficient of the element for fractionating mineral phases, and

F - Fraction of melt remaining during crystallisation

Geochemical Modelling

The trace element modelling was carried out in two steps (cf., Turner et al., 1992). First an intermediate melt composition was derived from the two chosen end member composition of the Pitepani tholeiite (AM-19 and AM-32), using Kd values for basic magmas. The intermediate melt compositions were further fractionated with new sets of K d

values for acidic compositions (Table 2) to derive the granitic end member compositions (MM-27 and C-317).

The composition of various crystallising phases was calculated by the software 'FC-AFC-FCA and Mixing modeller' and the proportion of phases was varied, in order to

Table 2: Kd values (after Ersoy and Helvaci, 2009) used in the trace element modelling.

Acidic melt composition Basic melt composition

Cs 0.01 0.01 0.01 2.2 0.11 0.03 0.01 0.0004 0.01 0.13 0.13 Rb 0.028 0.03 0.18 4.5 0.61 0.24 0.045 0.029 0.002 0.003 0.0047 0.1 K 0.001 0.037 0.081 2.5 1.49 0.263 0.045 0.013 0.0091 0.0072 0.156 0.045Ba 0.2 0.4 0.28 6.4 7.2 0.363 0.002 0.002 0.0006 0.3 Sr 0.1 0.15 0.25 0.25 4.5 4.4 0.077 0.74 0.0022 0.007 0.0963 2 Pb 0.028 0.32 0.53 0.89 0.12 1.3 0.03 0.71 0.56 7.5 0.53 0.0001 0.0013 0.0056 0.36

Th 0.16 0.35 0.16 0.31 0.022 0.04 0.427 22.1 0.04 0.13 0.03 0.01 U 0.12 0.002 0.1 0.04 0.05 43.7 0.21 0.063 254 11.9 0.045 0.035 0.04 0.01 Zr 0.25 0.6 0.34 0.19 0.01 0.041 0.5 3.9 0.49 0.0045 0.03 0.121 0.048 0.1Hf 0.2 0.247 0.52 0.5 0.02 0.039 0.065 2645 0.0037 0.055 0.263 0.051 3Ti 0.7 0.9 7 0.05 150 0.011 0.024 0.1 0.04 7.5Ta 0.5 0.35 1.5 1.3 0.001 0.03 1.2 18 40.2 1.9 0 0.15 0.013 0.04 5Y 1 2.7 2.46 2.3 0.017 0.51 40 0.12 0.27 71.4 95.5 0.0038 0.2 0.438 0.03 0.2Nb 0.54 0.8 1.5 4.6 0.01 0.26 0.1 6.58 0.12 0.0017 0.15 0.0027 0.01 0.4

Sc 18 14 2.23 0.023 0.01 5.9 60.3 0.68 1.2 3.2 0.04 Cr 21 12.6 0.01 3 119 0.7 10 34 0.08 153Ni 4.9 6.2 9.3 3.33 1.1 1.5 5.1 6.2 29 5 14 0.04 29Co 37 28.5 0.15 26 9 5.9 3 2 0.07 7.4V 4.92 0.8 0.6 1.35 0.022 26Ga 2.42 3.1 0.45 3.2 2.8 0.22 Zn 10.7 11.4 0.042 0.48 26.6 1.2 Cu 0.49 72.4 0.24 3.8 3.2

La 1.5 1.2 1.5 0.318 0.07 0.393 1.1 1.3 0.0006 0.002 0.0435 0.27 1.5Ce 1.5 1 1.7 0.377 0.02 0.251 16.6 1.19 2.04 0.0005 0.003 0.0843 0.2 1.3Pr 2 2 3.5 0.3 0.025 0.2 18 2.54 0.0008 0.0048 0.124 0.17 Nd 2.5 2.5 4 0.339 0.03 0.189 21 0.96 3.35 0.001 0.0048 0.173 0.14 1Sm 2.5 3 6 0.39 0.02 0.137 20.7 0.684 3.79 0.0013 0.01 0.283 0.11 1.1Eu 0.9 3 5 0.328 3.3 2.11 14.5 0.4 0.45 0.0016 0.013 0.312 0.73 0.6Gd 1.2 3 7.5 0.442 0.011 0.12 21.7 9.21 0.0015 0.016 0.336 0.066 Tb 2 4 8 0.393 0.01 0.15 0.36 24.8 0.0015 0.019 0.364 0.06 1Dy 1.5 3.5 9 0.5 0.04 0.112 16.9 0.37 38.8 0.0017 0.022 0.363 0.055 Ho 2 3.2 10 0.75 0.014 0.14 74.5 0.0016 0.026 0.378 0.048 Er 0.6 2.6 10 0.4 0.006 0.122 14.1 99.8 0.0015 0.03 0.351 0.041 Tm 1.5 2.5 9 0.66 0.014 0.1 150 0.0015 0.04 0.297 0.036 1Yb 1.5 2.5 7 0.45 0.03 0.132 9.4 0.55 194 0.0015 0.049 0.313 0.031 0.9Lu 1.5 3 6 0.45 0.02 0.138 7.9 0.74 264 0.0015 0.06 0.265 0.025

Ele

men

ts

Pla

gioc

lase

Apa

tite

Mag

neti

te

Ilm

enit

e

Zir

con

All

anit

e

Oli

vine

O-p

yrox

ene

C-p

yrox

ene

Pla

gioc

lase

Mag

neti

te

O-p

yrox

ene

C-p

yrox

ene

Am

phib

ole

Bio

tite

K-F

elds

par

LIL

EH

FS

EO

TH

ER

SR

EE


generate melt compositions that are closest to the desired liquid composition. The primitive composition of AM-19 was fractionated to an intermediate melt composition by fractionating the phases: 13% Olivine, 25% Orthopyroxenes, 60% Clinopyroxenes and 2% Plagioclase. The K values used d

for trace element modelling, in the first stage, are of a basic melt composition (Table 2). The intermediate melt composition was again fractionated in the second stage with the phases: 19% Orthopyroxenes, 29.7% Clinopyroxenes, 19% Plagioclase, 24% Magnetite, 5% Amphibole, 3% Illmenite, and 0.1% each of Apatite, Zircon and Allanite. During the second stage of fractionation, the K values for d

acidic composition were used (Table 2). Sample AM-32 was fractionated by crystallising the phases: 28.5% Orthopyroxenes, 43.5% Clinopyroxenes, 19% Plagioclase and 9% Magnetite to derive the intermediate melt composition. The intermediate melt was again fractionated by crystallising the phases: 8% Orthopyroxenes, 13% Clinopyroxenes, 30% Plagioclase, 20% K-feldspar, 20% Magnetite, 5% Amphibole, 1.4% Illmenite, and 0.6% Zircon, to obtain the A-type granite composition that is similar to C-317.

Results

The primitive mantle normalised trace element diagram and chondrite normalised REE pattern are shown in Fig.12 and Fig.13, for the modelled as well as the actual compositions of the Dongargarh A-type granites. The close similarity between modelled composition and Dongargarh A-type granites (MM-27 and C-317) show that the Dongargarh A-type granites can indeed be generated by extreme crystal fractionation of Pitepani tholeiites.

The relatively high concentration of comparatively mobile elements such as U, Th, K and Ba in the Dongargarh A-type granites are related to their mobile nature; a feature supported by the scatter of these elements on Harker plots and the presence of uranium deposits in the Dongargarh granites. However, the REE and relatively immobile and incompatible trace element pattern of the Samples MM-27 and C-317 are nearly similar to those obtained by extensive fractionation of the Pitepani tholeiites and can produce highly reduced melts that was favourable for the development of rapakivi textures (Frost and Frost, 1997). The results of the modelling are given in Table 3.

Fig.12. Spider diagrams showing similarity between MM-27 and derivative of AM-19. Note: 'solid circles' represent MM-27 while 'cross' represents derivative of AM-19.

Fig. 13. Spider diagrams showing similarity between C-317 and derivative of AM-32. Note: 'triangles' (blue) represent C-317 while 'cross' (red) represents derivative of AM-32.


Discussion and Conclusions

The Dongargarh A-type granites show typical characters of A-type granites and accordingly require a petrogenetic origin unlike to that of I- and S-type Dongargarh granites. Noteworthy features such as high incompatible/compatible element ratios, large negative Eu anomalies, bimodal association, high magma temperatures and relatively anhydrous mineralogy of A-type granites are easily reconciled by the model involving fractionation from the mafic magma.

#Large variations in Mg and LREE enriched patterns also supports the fractionation model for the origin of Dongargarh A-type granites.

The successful trace element and REE modelling of the Dongargarh A-type granites via extreme fractionation of Pitepani tholeiites strongly implicates the genetic relationship between mantle derived melts and the generation of voluminous Dongargarh A-type granites. The Pitepani tholeiites were neither derived from a primitive garnet-bearing

deep mantle source nor from ocean island basalt (OIB) mantle source. Instead they were derived from a depleted N-type mid-ocean ridge basalt (N-MORB) source and represent asthenospheric decompression melting in response to slab retreat (Asthana et al., 2010, 2012). Accordingly, the Dongargarh A-type granites also formed in a rifting active continental margin/back-arc basin. This interpretation is independently corroborated by the A character of these 2

granites. Furthermore, this work shows that the Dongargarh A-type granites were neither related to continental rifting nor to a mantle plume and supports the original chronostratigraphy presented by Sarkar (1957, 1958, 1994).

Acknowledgements

This study is based on the major and trace element analyses of the Dongargarh granites given by Narayana et al. (2000) and the Pitepani tholeiites analysed by Pophare (2001) utilising funds from CSIR project No.024 (215)/92/EMR-II.

Neoarchaean Dongargarh Rapakivi A-type Granites and its Relationship to Pitepani Tholeiites

Table 3: Trace element modelling results of the Dongargarh A-type granites (MM-27 and C-317) derived from extensive fractionation of Pitepani

tholeiites (AM-19 and AM-32).

Intermediate melt Final melt Intermediate melt Final melt

Elements AM 32 composition composition C-317 Elements AM-19 composition composition MM-27

(70% Fractionation) (66% Fractionation) (56% Fractionation) (30% Fractionation)

Cs 0.57 1.72 4.63 1.8 Cs 0.62 1.32 1.87 1.4

Rb 39.48 128.18 270.37 135 Rb 39.47 89.28 123.97 116

Ba 227.3 706.7 153.61 806 Ba 196.13 443.15 581.35 1232

Sr 308.98 618.26 16.34 85 Sr 175.76 368.03 374.13 63

Th 5.1 15.97 37.63 22.6 Th 0.49 1.06 1.42 8.5

U 1.21 3.89 2.68 3.5 U 0.1 0.22 0.28 2.3

Zr 181.19 548.97 598.55 264 Zr 67.18 142.78 132.9 151

Hf 8153 16593.43 0.03 5 Hf 1.6 3.15 1.67 4.1

Ta 0.49 0.89 1 1.6 Ta 0.28 0.61 0.57 1.5

Nb 8.39 25.34 44.11 36 Nb 4.86 10.69 12.01 15

Y 38.27 92.03 79.03 50 Y 27.08 47.56 40.79 40

Sc 41.24 16.89 3.08 4 Sc 41.6 14.2 4.27 3

V 351.02 27.93 62.99 0 V 272.24 258.21 337.89 0.7

Cr 121.22 0 0 1 Cr 160.86 0 0 0.3

Ni 59.02 0 0 2 Ni 75.07 0 0 2

Co 63.38 11.69 1.55 64 Co 64.8 15.81 8.56 68

La 23.7 61.66 104.5 180.73 La 5.68 12.57 13.38 12.66

Ce 50.28 132.92 240.93 321.36 Ce 13.93 30.25 32.94 31.55

Pr 6.37 19.11 27.02 27.14 Pr 2.2 4.69 4.37 5.32

Nd 27.02 71.37 86.23 110.6 Nd 11.35 23.61 19.8 23.34

Sm 5.63 13.96 14.4 14.59 Sm 3.67 7.23 5.59 6.58

Eu 1.56 3.49 1.16 1.34 Eu 1.18 2.27 1.75 1.56

Gd 5.9 16.16 16.81 10.45 Gd 4.01 7.69 6.36 6.2

Dy 5.65 15.26 11.34 9.82 Dy 3.9 7.37 5.45 6.45

Er 3.66 9.95 6.25 1.58 Er 2.4 4.56 3.8 3.73

Yb 3.46 8.67 3.55 4.21 Yb 2.06 3.97 3.19 3.6

Lu 0.52 1.47 0.4 0.56 Lu 0.36 0.71 0.54 0.5

Eu/Eu* 0.827 0.71 0.227 0.331 Eu/Eu* 0.939 0.931 0.897 0.746






Cs 0.57 1.72 4.63 1.8 Cs 0.62 1.32 1.87 1.4

Rb 39.48 128.18 270.37 135 Rb 39.47 89.28 123.97 116

Ba 227.3 706.7 153.61 806 Ba 196.13 443.15 581.35 1232

Sr 308.98 618.26 16.34 85 Sr 175.76 368.03 374.13 63

Th 5.1 15.97 37.63 22.6 Th 0.49 1.06 1.42 8.5

U 1.21 3.89 2.68 3.5 U 0.1 0.22 0.28 2.3

Zr 181.19 548.97 598.55 264 Zr 67.18 142.78 132.9 151

Hf 8153 16593.43 0.03 5 Hf 1.6 3.15 1.67 4.1

Ta 0.49 0.89 1 1.6 Ta 0.28 0.61 0.57 1.5

Nb 8.39 25.34 44.11 36 Nb 4.86 10.69 12.01 15

Y 38.27 92.03 79.03 50 Y 27.08 47.56 40.79 40

Sc 41.24 16.89 3.08 4 Sc 41.6 14.2 4.27 3

V 351.02 27.93 62.99 0 V 272.24 258.21 337.89 0.7

Cr 121.22 0 0 1 Cr 160.86 0 0 0.3

Ni 59.02 0 0 2 Ni 75.07 0 0 2

Co 63.38 11.69 1.55 64 Co 64.8 15.81 8.56 68

La 23.7 61.66 104.5 180.73 La 5.68 12.57 13.38 12.66

Ce 50.28 132.92 240.93 321.36 Ce 13.93 30.25 32.94 31.55

Pr 6.37 19.11 27.02 27.14 Pr 2.2 4.69 4.37 5.32

Nd 27.02 71.37 86.23 110.6 Nd 11.35 23.61 19.8 23.34

Sm 5.63 13.96 14.4 14.59 Sm 3.67 7.23 5.59 6.58

Eu 1.56 3.49 1.16 1.34 Eu 1.18 2.27 1.75 1.56

Gd 5.9 16.16 16.81 10.45 Gd 4.01 7.69 6.36 6.2

Dy 5.65 15.26 11.34 9.82 Dy 3.9 7.37 5.45 6.45

Er 3.66 9.95 6.25 1.58 Er 2.4 4.56 3.8 3.73

Yb 3.46 8.67 3.55 4.21 Yb 2.06 3.97 3.19 3.6

Lu 0.52 1.47 0.4 0.56 Lu 0.36 0.71 0.54 0.5

Eu/Eu* 0.827 0.71 0.227 0.331 Eu/Eu* 0.939 0.931 0.897 0.746






Cs 0.57 1.72 4.63 1.8 Cs 0.62 1.32 1.87 1.4

Rb 39.48 128.18 270.37 135 Rb 39.47 89.28 123.97 116

Ba 227.3 706.7 153.61 806 Ba 196.13 443.15 581.35 1232

Sr 308.98 618.26 16.34 85 Sr 175.76 368.03 374.13 63

Th 5.1 15.97 37.63 22.6 Th 0.49 1.06 1.42 8.5

U 1.21 3.89 2.68 3.5 U 0.1 0.22 0.28 2.3

Zr 181.19 548.97 598.55 264 Zr 67.18 142.78 132.9 151

Hf 8153 16593.43 0.03 5 Hf 1.6 3.15 1.67 4.1

Ta 0.49 0.89 1 1.6 Ta 0.28 0.61 0.57 1.5

Nb 8.39 25.34 44.11 36 Nb 4.86 10.69 12.01 15

Y 38.27 92.03 79.03 50 Y 27.08 47.56 40.79 40

Sc 41.24 16.89 3.08 4 Sc 41.6 14.2 4.27 3

V 351.02 27.93 62.99 0 V 272.24 258.21 337.89 0.7

Cr 121.22 0 0 1 Cr 160.86 0 0 0.3

Ni 59.02 0 0 2 Ni 75.07 0 0 2

Co 63.38 11.69 1.55 64 Co 64.8 15.81 8.56 68

La 23.7 61.66 104.5 180.73 La 5.68 12.57 13.38 12.66

Ce 50.28 132.92 240.93 321.36 Ce 13.93 30.25 32.94 31.55

Pr 6.37 19.11 27.02 27.14 Pr 2.2 4.69 4.37 5.32

Nd 27.02 71.37 86.23 110.6 Nd 11.35 23.61 19.8 23.34

Sm 5.63 13.96 14.4 14.59 Sm 3.67 7.23 5.59 6.58

Eu 1.56 3.49 1.16 1.34 Eu 1.18 2.27 1.75 1.56

Gd 5.9 16.16 16.81 10.45 Gd 4.01 7.69 6.36 6.2

Dy 5.65 15.26 11.34 9.82 Dy 3.9 7.37 5.45 6.45

Er 3.66 9.95 6.25 1.58 Er 2.4 4.56 3.8 3.73

Yb 3.46 8.67 3.55 4.21 Yb 2.06 3.97 3.19 3.6

Lu 0.52 1.47 0.4 0.56 Lu 0.36 0.71 0.54 0.5

Eu/Eu* 0.827 0.71 0.227 0.331 Eu/Eu* 0.939 0.931 0.897 0.746

37

Ahmad, T., Wanjari, N., Kaulina, T.V., Mishra, M.K and Nitkina, E.A.

(2008). Geochemical and isotopic characteristics of the Amgaon

gneissic complex, Central Indian Shield: Constraints on

Precambrian crustal evolution. In: Proc. Int. Symp. 'Geoscience thResources and Environments of Asian Terranes (GREAT-2008), 4

thIGCP 516, and 5 APSEG;' November 24-26, 2008, Bangkok,

Thailand.

Asthana, D., Dash, M.R., Pophare, A.M and Khare, S.K. (1996).

Interstratified low-high Ti volcanics from arc related Khairagarh

Group of Central India. Curr. Sci., v. 71, pp. 304 -306.

Asthana, D., Khare, S.K., Pophare, A.M and Dash, M.R. (1997).

Comments on 'Geochemistry of the Dongargarh volcanic rocks,

Central India: implications for the Precambrian mantle'. Precamb.

Res. v. 84, pp. 105-107.

Asthana, D., Kimura, J.I., Shinjo, R., Katukase, M. and Pophare, A.M.

(2006). Geochemical and Sr-Pb-Nd-Hf isotopic study of

Neoarchaean “Setouchi-type” high-magnesium andesite suite from

Central India. Geochim. Cosmochim. Acta, v. 70 (18), Supplement th st1, pp. A24-A24, (16 Annual V.M. Goldschmidt Conference 31

A u g u s t 2 0 0 6 , M e l b o u r n e , A u s t r a l i a ) .

doi:10.1016/j.gca.2006.06.062

Asthana, D., Pophare, A.M, Crawford, T. and Kanojkar, D. (2010). The

Dongargarh bimodal volcanic province and the large igneous

province conundrum. Geochim. Cosmochim. Acta, v. 74 (12), thSupplement 1, pp. A35. (20 Annual V. M. Goldschmidt

Conference 13-18 August, 2010, Knoxville, Tennessee).

Asthana, D., Prophare, A.M. and Kumar, H. (2012). The Dongargarh-

Kotri Belt: An Intra-continental rift or an Andean-type active

continental margin related mobile belt? In: National workshop on

recent advances in geology of Dongargarh-Kotri belt, central India

and its mineral potential, AMD and Gondwana Geol. Soc., Nagpur,

pp.12-15.

Balaram, V. (1995). Developments and trends in ICP–MS and its

influence on the recent changes in trace element analysis. Curr. Sci.,

v. 69, pp. 640-649.

Barbarin, B. (1999). A review of the relationships between granitoids

types, their origins and their geodynamic environments. Lithos, v.

46, pp. 605-626.

Barker, F., Wones, D.R., Sharp, W.N. and Desborough, G.A. (1975). The

Pikes Peak batholith, Colorado Front Range and a model for the

origin of the gabbro-anorthosite-syenite-potassic granite suite.

Precamb. Res., v. 2, pp. 97-160.

Bhandari, A., Pant, N.C., Bhowmik, S.K and Goswami, S. (2010). ~1.6

Ga ultrahigh temperature granulite metamorphism in the Central

Indian Tectonic Zone: insights from metamorphic reaction history,

geothermobarometry and monazite chemical ages. Geol. Jour. v.

45, pp. 1-19. doi:10.1002/gj.1221.

Bleeker, W. (2003). The late Archaean record: A puzzle in ca. 35 pieces.

Lithos, v. 71(2-4), pp. 99-134.

Bonin, B. (2007). A-type granites and related rocks: Evolution of a

concept, problems and prospects. Lithos, v. 97, pp. 1-29.

Boynton, W.V. (1984). Geochemistry of the rare earth elements; meteoric

studies. In: Henderson, P. (ed.), Rare earth elements geochemistry.

Elsevier Sci. Pub, Amsterdam, The Netherlands, pp. 63-114.

Chappell, B.W. and White, A.J.R. (1974). Two contrasting granite types.

Pac. Geol. v. 8, pp. 173–174.

Chen, L., Ma, C.Q., She, Z.B., Mason, R., Zhang, J.Y. and Zhang, C.

(2009). Petrogenesis and tectonic implications of A-type granites in

the Dabie orogenic belt, China: geochronological and geochemical

constraints. Geol. Mag., v. 146(5), pp. 638-651.

Clemens, J.D., Holloway, J.R. and White, A.J.R. (1986). Origin of A-type

granite: Experimental constraints. Am. Mineral., v. 71, pp. 317-324.

Collins, W.J., Beams, S.D., White, A.J.R. and Chappell, B.W. (1982).

Nature and origin of A-type granites with particular reference to

southeastern Australia. Contrib. Mineral. Petrol. v. 80, pp.189-200.

Cox, K.G., Bell, J.D. and Pankhurst, R.J. (1979). The Interpretation of

Igneous Rocks. George Allen and Unwin, London, 452p.

Creaser, R.A., Price, R.C and Wormald, R.J. (1991). A-type granites

revisited: assessment of a residual-source model. Geology, v. 19,

pp. 163-166.

Deshpande, G.G. (1984). Petrology of the Dongargarh granites of Chandi

Dongri area, Drug district, Madhya Pradesh. Geol. Surv. India, Sp.

Publ. No. 12, pp. 7-15.

Deshpande, G.G., Mohabey, N.K and Deshpande, M.S. (1990)

Petrography and tectonic setting of Dongargarh volcanic. Geol.

Surv. India, Sp. Publ. No. 28, pp. 260-288.

Eby, G.N. (1990). The A-type granitoids: a review of their occurrence and

chemical characteristics and speculation on their petrogenesis.

Lithos, v. 26, pp. 115-134.

Eby, G.N. (1992). Chemical subdivision of the A-type granitoids:

Petrogenetic and tectonic implications. Geology, v. 20, pp. 641-

644.

Ersoy, Y. and Helvaci, C. (2009). FC-AFC-FCA and mixing modeler: A

Microsoft Excel spread sheet program for modeling geochemical

differentiation of magma by crystal fractionation, crustal

assimilation and mixing. Compu. Geosci. doi: 10.1016/j.cageo.

2009.06.007.

Frost, C.D. and Frost, B.R. (1997). Reduced rapakivi-type granites: the

tholeiite connection. Geology, v. 25, pp. 647-650.

Frost, B.R., Barnes, C.G., Collins, W.J., Arculus, R.J., Ellis, D.J. and

Frost, C.D. (2001). A geochemical classification for granitic rocks.

Jour. Petrol., v. 42, pp. 2033-2048.

Govil, P.K. (1985). X-ray fluorescence analysis of major, minor and

selected trace elements in new IWG reference rock samples. Jour.

Geol. Soc. India, v. 26, pp. 38-42.

Jiang, N., Zhang, S., Zhou, W. and Liu, Y. (2009). Origin of a Mesozoic

granite with A-type characteristics from the North China craton:

highly fractionated from I-type magmas? Contrib. Mineral. Petrol.,

v. 158, pp. 113-130.

Kemp, A.I.S., Hawkesworth, C.J., Foster, G.L., Paterson, B.A.,

Woodhead, J.D., Hergt, J.M., Gray, C.M. and Whitehouse, M.

(2007). Magmatic and crustal differentiation history of granitic

rocks from Hf–O isotopes in zircon. Science, v. 315, pp. 980-983.

Kemp, A.I.S., Hawkesworth, C.J., Collins, W.J., Gray, C.M., Blevin, P.L.

and EIMF (2009). Isotopic evidence for rapid continental growth in

an extensional accretionary orogen: The Tasmanides, eastern

Deepanker Asthana et al.

References

38

Australia. Earth Planet. Sci. Lett., doi: 10.1016 /j.epsl.2009.05.011.

King, P.L., White, A.J.R. and Chappell, B.W. (1997). Characterization

and origin of aluminous A-type granites of the Lachlan Fold belt,

southeastern Australia. Jour. Petrol., v. 36, pp. 371-391.

Krishnamurthy, P., Chaki, A., Pandey, B.K., Chimote, J.S. and Singh,

S.N. (1988a). Geochronology of the granite-rhyolite suites of the thDongargarh Supergroup, Central India. 4 NSMS, Bangalore,

Preprint Vol., EPS 2, pp. 1-5.

Krishnamurthy, P., Chaki, A., Sinha, R.M. and Singh, S.N. (1988b).

Geology, geochemistry and genesis of metabasalts, metarhyolites,

and the associated uranium mineralization at Bodal, Rajnandgaon

district, Madhya Pradesh and implications for uranium exploration

in Central India. Expl. Res. Atomic Min., v. 1, pp. 13-39.

Krishnamurthy, P., Sinha, D.K., Rai, A.K., Seth, D.K. and Singh, S.N.

(1990). Magmatic rocks of the Dongargarh Supergroup, Central

India and implications on metallogeny. Geol. Surv. Spl. Publ. No.

28, pp. 303-319.

Landenberger, B. and Collins, W.J. (1996). Derivation of A-type granites

from a dehydrated charnockitic lower crust: evidence from the

Chaelundi Complex, Eastern Australia. J. Petrol. v. 37, pp.

145–170.

Loiselle, M.C. and Wones, D.R. (1979). Characteristics and origin of an-

orogenic granites. Geol. Soc. Am. Bull. Abstr. Prog., v. 92, pp. 468.

Mark, G. (1999). Petrogenesis of Mesoproterozoic K-rich granitoids,

southern Mt Angelay igneous complex, Cloncurry district,

northwest Queensland. Australian Jour. Earth Sci. v. 46, pp.

933–949.

Narayana, B.L., Rao, J.M., Rao, M.V.S., Murthy, N.N. and Rao, V.D.

(2000). Geochemistry and origin of early Proterozoic Dongargarh

rapakivi granite complex, Central India-An example for magma

mixing and differentiation. Gond. Res., v. 3(4), pp. 507-520.

Neogi, S., Miura, H. and Hariya, Y. (1996). Geochemistry of Dongargarh

volcanic rocks, Central India: Implications for the Precambrian

mantle. Precamb. Res., v. 76, pp. 77-91.

O'Connor, J.T. (1965). A classification for quartz rich igneous rocks based

on feldspar ratios. U.S. Geol. Surv. Prof. Paper-525-B, pp. 79-84.

Pandey, B.K., Krishnamurthy, P. and Gupta, J.N. (1993). Sm-Nd and Pb-

Pb geochronology of the Dongargarh granites, Central India: thImplications to petrogenesis. 6 NSMS, Dehradun, Preprint Vol.,

pp. 503-505.

Patiño Douce, A. E. and Beard, J.S. (1995). Dehydration melting of

biotite gneiss and quartz amphibolite from 3 to 15 kbar. J. Petrol. 36,

pp. 707-738.

Patiño Douce, A.E. (1997). Generation of metaluminous A-type granites

by low-pressure melting of calc- alkaline granitoids. Geology, v.

25(8), pp743-746.

Pearce, J.A., Harris, N.B.W. and Tindle, A.G. (1984). Trace element

discrimination diagrams for the tectonic interpretation of granitic

rocks. Jour. Petrol., v. 25, pp. 956-983.

Pophare, A.M. (2001). Petrogenesis of Pitepani volcanics, Central India

with special reference to relict clinopyroxene chemistry. Unpubl.

Ph.D. thesis, Indian School of Mines, Dhanbad, India, 168p.

Radhakrishnan, B.P. and Naqvi, S.M. (1986). Precambrian continental

crust of India and its evolution. Jour. Geol., v. 94, pp. 145-166.

Ramakrishnan, M. and Vaidyanadhan, R. (2008). Geology of India.

Memoir Geol. Soc. India, Vol. 1, pp.181-209.

Rajurkar, S.T., Bhate, V.D. and Sharma, S.B. (1990). Lineament fabric of

Madhya Pradesh and Maharashtra and its tectonic significance.

Geol. Surv. India, Spl. Publ. No. 28, Precambrian of Central India,

pp. 241-259.

Sarbadhikari, A.B. and Bhowmik, S.K. (2008). Constraining the

metamorphic evolution of a cryptic hot Mesoproterozoic orogen in

the Central Indian Tectonic Zone, using P–T pseudosection

modelling of mafic intrusions and host reworked granulites.

Precamb. Res., v. 162, pp. 128-149.

Sarkar, S.N. (1957). Stratigraphy and tectonics of Dongargarh System: A

new system in the Precambrian of Bhandara-Durg Balaghat area,

Bombay and M.P. Indian Inst. Tech. Jour. Sci. Engg. Res.

Kharagpur, v. 1, pp. 237-268.

Sarkar, S.N. (1958). Stratigraphy and tectonics of the Dongargarh System

: A new system in the Precambrian of Bhandara-Durg-Balaghat

area, Bombay and M.P., Indian Inst. Tech. Jour. Sci. Engg. Res.

Kharagpur, v. 2, pp. 145-160.

Sarkar, S.N., Gopalan, K. and Trivedi, J.R. (1981). New data on the

geochronology of the Precambrians of Bhandara-Durg, Central

India. Indian Jour. Earth Sci., v. 8, pp. 131-151.

Sarkar, S.N. (1994). Chronostratigraphy and tectonics of the Dongargarh

Supergroup Precambrian rocks in Bhandara-Durg region, Central

India. Indian Jour. Earth Sci. v. 21, pp. 19-31.

Sensarma, S., Palme, H. and Mukopadhyay, D. (2002). Crustal mantle

interaction in the genesis of siliceous high magnesian basalts:

evidence from the early Proterozoic Dongargarh Supergroup, India.

Chem. Geol., v. 187, pp. 1-17.

Sensarma, S. and Mukhopadhyay, D. (2003). New insight on the

stratigraphy and volcanic history of the Dongargarh Belt, central

India. Gond. Geol. Magz. Spl. Vol. No. 7. pp. 129-136.

Sensarma, S., Hoerness, S. and Mukhopadhyay, D. (2004). Relative

contributions of crust and mantle to the origin of the Bijili

Rhyolite in a Palaeoproterozoic bimodal volcanic sequence

(Dongargarh Group), Central India. Proc. Indian Acad. Sci. v. 113,

pp. 619-648.

Sensarma, S. (2007). A bimodal large igneous province and the plume

debate: The Palaeoproterozoic Dongargarh Group, Central India.

In: Foulger, G.R. and Jurdy, D.M. (eds.), Plates, plumes and

planetary processes: Geol. Soc. Am. Spl. paper 430, pp. 831-839,

doi: 10.1130/2007.2430 (38).

Streckeisen, A. (1976). To each plutonic rock its proper name. Earth Sci.

Rev., v. 12, pp. 1-33.

Sun, S.S. and McDonough, W.F. (1989). Chemical and isotopic

systematics of oceanic basalts; implications for mantle composition

and processes. In: Saunders, A.D. and Norry, M.J. (eds.),

Magmatism in the Oceanic Basins. Geol. Soc. London Spl. Publ. v.

42, pp. 313-345

Taylor, S.R. and McLennan, S.M. (1985). The continental crust: Its

composition and evolution. Blackwell Scientific Publ., Boston,

Mass., 312p.

Turner, S.P., Foden, J.D. and Morrison, R.S. (1992). Derivation of some

A-type magmas by fractionation of basaltic magma: an example


from Padthaway Ridge, South Australia. Lithos, v. 28, pp. 51-179.

Vander Auwera, J., Bogaerts, M., Liegeois, J.P., Demaiffe, D., Wilmart,

E., Bolle, O. and Duchesne, J.C. (2003). Derivation of the 1·0 - 0·9

Ga ferro-potassic A-type granitoids of southern Norway by extreme

differentiation from basic magmas. Precamb. Res., v. 124, pp. 107-

148.

Watkins, J., Clemens, J. and Treloar, P. (2007). Archaean TTGs as sources

of younger granitic magmas: melting of sodic metatonalites at 0.6-

1.2 GPa. Contrib. Mineral. Petrol., v. 154, pp. 91–110.

Whalen, J.B., Currie, K.L. and Chappell, B.W. (1987). A-type granites:

geochemical characteristics, discrimination and petrogenesis.

Contrib. Mineral. Petrol., v. 95, pp. 407-419.

Wu, F.Y., Sun, D.Y., Li, H.M., Jahn, B.M. and Wilde, S. (2002). A-type

granites in northeastern China: age and geochemical constraints on

their petrogenesis. Chem. Geol., v.187, pp. 143–73.

Winchester, J.A. and Floyd, P.A. (1977). Geochemical discrimination of

different magma series and their differentiation products using

immobile elements. Chem. Geol., v. 20, pp. 325-343.

Yang, J.H., Wu, F.Y., Chung, S.L., Wilde, S.A. and Chu, M.F. (2006).

A hybrid origin for the Qianshan A-type granite, northeast

China: Geochemical and Sr–Nd–Hf isotopic evidence. Lithos, v. 89,

pp.89-106.

Yedekar, D.B., Jain, S.C., Nair, K.K.K. and Dutta, K.K. (1990). The

Central Indian collision suture. Geol. Surv. India, Sp. Publ. No. 28,

pp. 1-43.

Zhao, X.F., Zhou, M.F., Li, J.W. and Wu, F.Y. (2008). Association

of Neoproterozoic A- and I-type granites in South China:

Implications for generation of A-type granites in a subduction-

related environment. Chem. Geol., doi:10.1016/j.chemgeo.

2008.07.018.


Neoarchaean Dongargarh Rapakivi A-type Granites and its Relationship to Pitepani Tholeiites

Documents

Transcript of Neoarchaean Dongargarh Rapakivi A-type Granites and its Relationship to Pitepani Tholeiites