Abstract
Here we present, Anisotropy of Magnetic Susceptibility (AMS) studies on quartzites of Champaner Group, Gujarat, Western India. As quartzites are dominantly present within each formation of the Champaner Group, they have been selected for the study. Our study on AMS signifies two prominent striking planes of magnetic foliation within the rocks. The rocks have (i) ENE-WSW to E-W and (ii) N-S to NE-SW trends. The former trend matches with the regional magnetic foliation of Godhra Granites (GG) and neighboring Banded Gneisses (BG), while the later one does not match with any of the trends resulted due to last phase of deformation within Southern Aravalli Mountain Belt (SAMB). Such heterogeneity among the later trends signifies further continuation of emplacement of GG after syn-tectonic pulse and regional deformation. This latter phase of granite led to the development of broad open N-S trending folds within the supracrustals along with its basement and doming up of sequences towards the eastern periphery of the Champaner Group.
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1 Introduction
Rock samples when subjected to external magnetic field, certain minerals within the sample show same strength of induced magnetization in all directions and are considered as “magnetically isotropic”. On the contrary, there are few minerals in the rocks, which have different strength of induced magnetization in preferred directions are called as “magnetically anisotropic”. Such minerals have an Anisotropy of Magnetic Susceptibility (AMS). Variation in susceptibility in preferred directions creates susceptibility ellipsoid (Tarling and Hrouda 1993), having three principal axes—long, intermediate and short. These axes are the principal susceptibility axes represented in SI units as K1, K2 and K3, where K1 ≥ K2 ≥ K3. The axes of susceptibility ellipsoid generally show a preferred orientation of principal axes of the strain ellipsoid in tectonically deformed rocks (Hrouda and Janak 1976; Rathore 1979, Borradaile and Tarling 1981, 1984; Hrouda 1982; Borradaile and Mothersill 1984; Borradaile 1987, 1991; Borradaile and Alford 1987; Borradaile and Henry 1997).
In the present paper, we provide AMS data generated on quartzites of Champaner Group belonging to the Aravalli Supergroup with an aim of demonstrating the last deformation imprint recorded within this rock. With the help of the AMS data, strong correlation has been established between the deformation signatures pertaining to the Champaner Group along with its basement and the neighboring Pre-Cambrian stratigraphic units. The present attempt is to explore the AMS fabrics from Champaner Group of rocks, particularly quartzites, as emphases regarding the emplacement record of granite, to understand the SAMB tectonics operated at its southern margin.
2 Geological and Structural Setting
The Champaner Group, a part of upper Aravallis is exposed at the eastern most fringe of Gujarat, India (Gupta et al. 1997) (Fig. 1). It bears an important link between the main Aravalli domains with the Central Indian Tectonic Zone (CITZ). The Champaner Group consists variety of rock types such as quartzites of manganiferous and non-manganiferous variety, polymict and oligomict metaconglomerates, carbonaceous phyllites and schists, spotted slates, hornfelses, manganiferous phyllites, biotite schists, dolomitic limestones, calc-silicate rock and meta-greywackes, which overlies the Paleo-Proterozoic Pre-Champaner Gneissic Complex (PCGC) located at Chhota Udepur region–i.e. “considered basement”, comprising granite-gneisses, quartzites and pelitic gneisses (Gupta et al. 1992, 1997; Merh 1995; Srikarni and Das 1996; Karanth and Das 2000; Das 2003) (Fig. 2). The Champaner rocks show greenschist facies metamoprhism and hornfelses are developed at the contact aureole with granite intrusive. (Das et al. 2009; Joshi and Limaye 2018; Joshi 2019a, b). Granites located in and around Champaner Group indicate syn-to-post emplacement record. Timing of granites suggest a wide span of dates from 1.1 to 0.93 Ga (Joshi and Limaye 2018).
Structurally, the rocks including quartzites, show poorly deformed signatures having three phases of deformation, viz. D1, D2 and D3. The three phases of deformation have resulted into F1, F2 and F3 folds, respectively. D1-D2 resulted into F1-F2 are coaxial having ESE-WNW and E-W trend, respectively, while the D3 shows folds having NNW-SSE to NNE-SSW trend. Combination of F1-3 folds have resulted into various interference fold patterns on regional as well as on the outcrop scale. The Type-III interference fold pattern has formed on account of regional deformation resulted due to combinations of F1-2 folds, whereas the Type-I interference pattern superimposed orthogonally over Type-III, which led to the development of domes. This last axial trace generated on account of superimposition is produced by later granitic pulse, represents F3 folds (Joshi 2019a, b). In addition, there has been observed evidences of out-of-sequence deformation (i.e. trends, which not concomitant with F1, F2 and F3) demonstrate varied trends and meso-scale interference patterns inside the detached and isolated patches of calc-silicates, caught up within the granites (Joshi and Limaye 2018).
3 Anisotropy of Magnetic Susceptibility Studies on Quartzites, Principle and Methodology
Quartzites of the Champaner Group are hard, massive, compact; at times flaggy and whitish to dark grey and/or black in colour. They are highly jointed with variable grain size from fine to coarse and display varieties of primary sedimentary structures at different locations of the study area. By and large quartzites of the study area exhibit E-W to NW-SE strikes with variable dip directions. Petrographic study of quartzites reveal granoblastic polygonal, mosaic with two granular boundary varieties (i.e.) in-equigranular interlobate and seriate interlobate. The former type is observed in the quartz grains showing sutured boundaries with large scale variability in grain size, whereas the latter shows less size variation with sutured grain boundaries. At places the grains show inclusions of mica flakes especially Mn-rich-muscovite having colourless to faint green pleochroism (Patel et al. 2016).
The present section deals with the Anisotropy of Magnetic Susceptibility (AMS) studies carried out on quartzites of the Champaner Group. Oriented samples were collected at 12 localities across the Champaner Group and more than 60 cores were analyzed for the AMS study. These measurements were done using KLY-4 Kappabridge at Department of Geology and Geo-physics, Indian Institute of Technology, Kharagpur. The instrument gave the results for the following parameters: (1) the magnitude and orientations of three principal axes of the susceptibility ellipsoid viz. K1, K2 and K3, where K1 ≥ K2 ≥ K3; (2) mean susceptibility (km); (3) degree of anisotropy (Pj); (4) shape parameter (T); (5) magnitude of foliation (F) and (6) lineation (L) (Table 1). The quartzites of the study area reflect low Km values, having the mean susceptibility as 47.37 × 10−6 SI units. Some quartzites reveal exceptionally high mean susceptibility values more than 250 × 10−6 SI units, due to the presence of biotite content.
4 Result and AMS Data Interpretation
The orientations of all three principal axes K1, K2 and K3 have been plotted using lower hemisphere stereographic projection. The plane passes through K1-K2 and essentially matching with K3 pole defines the magnetic foliation (F). The F plane in the given figure is plotted with the dotted line. The stereographic net is also aided with the planar structure S0 (bedding plane) acquired through field and has been depicted by means of continuous line (Fig. 3). There are total 12 samples, viz. SN1-4, SN6, CPR1, CPR3-5 and CPR7-9, out of which 61 cores have been analyzed.
As mentioned in the geological and structural setting section, the Champaner Group shows three phases of deformation, viz. D1, D2 and D3, of which first two phases were co-axial (F1 ~ ESE-WNW; F2 ~ E-W) and the last phase of deformation has N-S trend. The response of all three phases of deformation has been recorded within the quartzites of the Champaner Group. The samples collected from the southern part of the study area, viz. CPR1, 3, 4 and 5 show dominance of F1 and F2 folds. The CPR1 sample has a dominance of F1 fabric on an outcrop scale due to the presence of mesoscale folds, but shows dominance of magnetic foliation in nearly E-W direction. The superimposition of F2 fabric over F1 is clearly seen in the sample collected from NW of Masabar (CPR1). CPR3 sample from the F2 limb portion show oblique relationship of the magnetic foliation with the bedding. CPR4 and 5 collected from F2 limb, depicts similar trend of bedding and magnetic foliation. These samples show the effect of F2 folds present in the southern part of the study area. The signatures of F3 fold or preferred orientation along N-S direction are not seen in the present samples. This suggests that the last episode of deformation did not show any mineral alignment in the southern part of the study area.
CPR 7 and SN2 sample collected from the eastern part of the study area from Narukot dome clearly signifies similar relationship of S0 and S1 in these quartzites. The SN2 sample collected from F1 fold limb and CPR 7 sample from F2 limb gives nearer results of F1 and F2 fabric. It suggests that although, there is a dominance of N-S deformation in the eastern part of the study area, the preferred magnetic fabric parallel to F3 is absent. Such condition has occurred due to the presence of F2 fold dominance in the Narukot area. Further to the west of the Narukot dome, the samples collected along the axial trace of the F2 fold (SN3, SN4 and SN6), show prominence of E-W magnetic foliation. The D2 imprint recorded within these rocks clearly suggests that the central part of the Champaner Group has a dominance of N-S shortening. The western and northern part of the study area shows the magnetic fabric parallel to the D3 deformation of the Champaner Group in the samples viz. CPR 8, CPR 9 and SN1. This magnetic fabric ranges from N-S to NE-SW; however there is no mesoscopic scale imprint of the late deformation in the present localities.
Jelinek plot (Pj vs. T) (Fig. 4), suggest that majority of the cores fall in the oblate field (flattening field) and few cores from the quartzites show their affinity towards prolate field (constrictional field). In order to examine the type of strain, the available AMS data has been plotted as Flinn diagram (F vs. L), which holds good correlation with the Jelinek plot. Most of the AMS data of cores from quartzites of the Champaner Group represented in the Flinn diagram concentrated in the oblate field and few around K = 1 line, which separates the prolate and the oblate field. This is an indication of the plane strain condition (Fig. 4).
5 Discussions
5.1 Significance of AMS Study for the Study Area
The AMS data results from quartzites of Champaner Group indicate that there exist two prominent striking planes of magnetic foliation, viz (i) ENE-WSW to E-W and (ii) N-S to NE-SW. The former range of strikes represent the first two phases (i.e. D1 = F1 ~ ESE-WNW and D2 = F2 ~ E-W), while the later orientation matches with the third deformational phase (i.e. D3 = F3 ~ NNW-SSE to NNE-SSW) recorded within the Champaner Group along with its basement.
Advancement in the present technique indicate that the Anisotropy of Magnetic Susceptibility (AMS) studies have been used to deduce the time relationship between emplacement/fabric development and regional deformation (Mamtani and Greiling 2005); in kinematic analysis and vorticity quantification of syn-tectonic granitoids (Tarling and Hrouda 1993; Benn et al. 1998, 1999, 2001; Majumder and Mamtani 2009; Mamtani et al. 2013); to capture imprints of superposed deformation in granitoids (Mondal 2018; Mamtani et al. 2019). In the light of this extensive work on Godhra and other granitoids, authors posit their AMS data set generated on quartzites by correlating it with the existing literature on structural and magnetic records related to the SAMB.
5.2 AMS of Adjoining Areas
The structural records from Pre-Cambrian stratigraphic units of SAMB, viz. (1) the Banded Gneisses (BG); (2) the Lunavada Group (LG); (3) the Champaner Group (CG) along with its basement (Pre-Champaner Gneissic Complex-PCGC); (4) the Godhra Granites (GG); signifies that each of the unit that belongs to the SAMB, except GG have underwent at least three phases of deformation (Table 2). Moreover, the magnetic records derived through BG, LG and GG, by the earlier workers state that these magnetic trends are coeval with the last phase of deformation (having strikes ~ WNW to WSW and plunge ~ NW to W), recorded within the SAMB (Mamtani and Greiling, 2005). Unlike in the case of CG, where the latest magnetic foliation (having strikes ~ N-S to NE-SW), demonstrating the last phase of deformation within CG, show a distinct heterogeneity in terms of trends recorded during the waning phase of SAMB. In addition, the strain estimation derived with the help of degree of magnetic anisotropy value (P′ or Pj) from Godhra granite samples, suggest that southern part of GG, in proximity to CITZ tends to show inflated P′ or Pj values, implying the rocks have accommodated higher strain condition than their northern counter parts (Mamtani et al. 2019). However, the quartzite samples collected from the eastern part of the Champaner Group, having predominantly N-S to NE-SW magnetic foliation reflects higher P′ or Pj value, suggests that the eastern part of the CG have accommodated high strain condition than any of the other direction (Table 1).
In order to understand the heterogeneity in terms of magnetic records, the study of granite located in and around the CG becomes vital. On the basis of structural data proposed by Joshi and Limaye (2018), suggests that the granites located in and around the Champaner region shows evidences of prolong emplacement records. One such evidence has been proposed by a field photograph published in Joshi and Limaye (2014), where, the coarse grained later pulse having intrusive relationship with the comparative fine grained granite variety. Also, the evidences suggested by Joshi (2019a) on genesis of interference fold patterns within CG, explained forceful emplacement of granite deforming the country rocks along N-S trend, on the basis of the model suggested by He et al. (2009) for Fangshan pluton, SW Beijing, China. In addition to that, the existing geo-chemical data of granites located in and around CG is in favor of two pulses revealing prior ‘S’ type granite (Goyal et al. 1997) and later the ‘A’ type variety representing transitional or post-orogenic uplift (suggested by Maithani et al. 1998 and Goyal et al. 2001). Finally, the Geophysical studies carried out within this terrain corroborate to the fact that there lies a sub-surface pluton beneath the CG, which has eventually up rooted the country rocks along with the pre-existing granitic pulse during the later stages (Joshi et al. 2018).
Hence based on the above facts it can be stated that the possibility of prolong emplacement record, which governed the tectonics of SAMB from its southern margin cannot be ruled out. At the end of regional deformation the granite pulse was still active at the southern margin deforming the Champaner metasediments along with its basement, to give rise different trends. These trends being restricted to the Champaner Group and its basement, have not been recorded in the neighboring supracrustals and thus how show heterogeneity in terms of last deformation imprint within the SAMB (Table 2).
6 Conclusion
-
1.
The AMS studies on quartzites from Champaner Group indicate two prominent striking planes of magnetic foliation, viz (i) ENE-WSW to E-W and (ii) N-S to NE-SW. These trends matches with the three deformational phases occurred within the present group, along with its basement (i.e. D1 = F1 ~ ESE-WNW and D2 = F2 ~ E-W; D3 = F3 ~ NNW-SSE to NNE-SSW).
-
2.
Correlating these magnetic fabrics of CG with the available structural and magnetic records from SAMB, suggest that there lies a distinct heterogeneity in case of latest trends of CG and SAMB.
-
3.
Degree of magnetic anisotropy value (P′ or Pj) from quartzite samples indicate that the eastern part of the Champaner Group has accommodated high strain condition than any of the other directions.
-
4.
The above facts are in favor of indicating the prolong emplacement record of GG, which governed the tectonics of SAMB from its southern margin.
-
5.
During the waning phase of regional deformation of CG, the emplacement was still continued to deformed the Champaner metasediments along N-S trend, along with its basement.
-
6.
As this latest trend was confined to the CG and its basement, have not been recorded with the neighboring supracrustals of SAMB.
References
Benn K, Ham MN, Pignotta GS, Bleeker W (1998) Emplacement and deformation of granites during transpression: magnetic fabrics of the Archean Sparrow pluton Slave Province, Canada. J Struct Geol 20:1247–1259
Benn K, Paterson SR, Lund SP, Pignotta GS, Kruse S (2001) Magmatic fabrics in batholiths as markers of regional strains and plate kinematics: example of the cretaceous Mt. Stuart Batholith. Phys Chem Earth Part—Solid Earth Geodesy 26(4–5):343–354
Benn K, Roest WR, Rochette P, Evans NG, Pignotta GS (1999) Geophysical and structural signatures of syntectonic batholiths construction: the south mountain batholith meguma terrane, Nova Scotia. Geophys J Int 136:144–158
Borradaile GJ (1987) Anisotropy of magnetic susceptibility: rock composition versus strain. Tectonophysics 138:327–329
Borradaile GJ (1991) Correlation of strain with anisotropy of magnetic susceptibility (AMS). Pure appl Geophys 135:15–29
Borradaile GJ, Alford C (1987) Relationship between magnetic susceptibility and strain in laboratory experiments. Tectonophysics 133:121–135
Borradaile GJ, Henry B (1997) Tectonic applications of magnetic susceptibility and its anisotropy. Earth-Sci Rev 42:49–93
Borradaile GJ, Mothersill JS (1984) Coaxial deformed and magnetic fabrics without simply correlated magnitudes of principal values. Phys Earth PI Sci Int 35:294–300
Borradaile GJ, Tarling DH (1981) The influence of deformation mechanisms on magnetic fabric in weakly deformed rocks. Tectonophysics 77:151–168
Borradaile GJ, Tarling DH (1984) Strain partitioning and magnetic fabrics in particulate flow. Can J Earth Sci 21:694–697
Das S (2003) Deformation and metamorphic history of the precambrian rocks in north eastern part of Vadodara district, Gujarat with a reference to the stratigraphy and tectonics. Unpublished Ph.D. Thesis, The M. S. University of Baroda, Vadodara, pp 1–110
Das S, Singh PK, Sikarni C (2009) A preliminary study of thermal metamorphism in the Champaner Group of rocks in Panchmahals and Vadodara districts of Gujarat. India J Geosci 63:373–382
Goyal N, Pant PC, Hansda PK, Pandey BK (2001) Geochemistry and Rb–Sr age of the late Proterozoic Godhra granite of central Gujarat, India. J Geol Soc India 58:391–398
Goyal N, Varughese SK, Hansda PK, Ramachandran S, Singh R (1997) Geochemistry of granites of Jambughoda, Panchmahals district, Gujarat and uranium mineralization in Champaner Group. J Geol Soc India 50:769–778
Gupta SN, Arora YK, Mathur RK, Iqbaluddin Prasad B, Sahai TN, Sharma SB (1997) The Precambrian geology of the Aravalli region, southern Rajasthan and NE Gujarat. Mem Geol Surv India 123:1–262
Gupta SN, Mathur RK, Arora YK (1992) Lithostratigraphy of Proterozoic rocks of Rajasthan and Gujarat—a review. Rec Geol Surv India 115:63–85
He B, Xu YG, Paterson S (2009) Magmatic diapirism of the Fangshan pluton, southwest of Beijing, China. J Struct Geol 31:615–626
Hrouda F (1982) Magnetic anisotropy of rocks and its application in geology and geophysics. Geophys Surv 5:37–82
Hrouda F, Janak F (1976) The changes in shape of the magnetic susceptibility ellipsoid during progressive metamorphism and deformation. Tectonophysics 34:135–148
Joshi AU (2019a) Fold interference patterns in Meso-Proterozoic Champaner fold belt (CFB) Gujarat, western India. J Earth Syst Sci. https://doi.org/10.1007/s12040-019-1075-z
Joshi AU (2019b) Structural evolution of precambrian rocks of Champaner Group, Gujarat, Western India. Unpublished Ph.D. Thesis, The Maharaja Sayajirao University of Baroda, pp 1–190
Joshi AU, Limaye MA (2014) Evidence of syndeformational granitoid emplacement within Champaner Group, Gujarat. J Maharaja Sayajirao Univ Baroda 49:45–54
Joshi AU, Limaye MA (2018) Rootless calc-silicate folds in granite: an implication towards syn to post plutonic emplacement. J Earth Syst Sci 127(5):ID67
Joshi AU, Sant DA, Parvez IA, Rangarajan G, Limaye MA, Mukherjee S, Charola MJ, Bhatt MN, Mistry SP (2018) Sub-surface profiling of granite pluton using microtremor method: Southern Aravalli, Gujarat, India. Int J Earth Sci 107:191–201
Karanth RV, Das S (2000) Deformational history of the pre-Champaner gneissic complex in Chhota Udepur area, Vadodara district, Gujarat. Indian J Geol 72:43–54
Maithani PB, Rathaiah YV, Varughese SK, Singh R (1998) Granites of Zoz area, Baroda District, Gujarat and its economic significance. J Geol Soc India 51:201–206
Majumder S, Mamtani MA (2009) Magnetic fabric in the Malanjkhand Granite (central India)—implications for regional tectonics and Proterozoic suturing of the Indian shield. Phys Earth Planet Inter 172:310–323. https://doi.org/10.1016/j.pepi.2008.10.007
Mamtani MA (1998) Deformational mechanisms of the Lunavada Pre-Cambrian rocks, Panchmahal district, Gujarat; Unpublished Ph.D. thesis, M.S. University of Baroda. pp 1–268
Mamtani MA (2014) Magnetic fabric as a vorticity gauge in syntectonically deformed granitic rocks. Tectonophys 629:189–196
Mamtani MA, Bhatt S, Rana V, Sen K, Mondal TK (2019) Application of AMS in understanding regional deformation fabric development and granite emplacement: examples from Indian cratons. Geol Soc, London, Spec Publ 489. https://doi.org/10.1144/SP489-2019-292
Mamtani MA, Greiling RO (2005) Granite emplacement and its relation with regional deformation in the Aravalli Mountain Belt (India)—Inferences from magnetic fabric. J Struct Geol 27:2008–2029
Mamtani MA, Karmakar B, Merh SS (2002) Evidence of polyphase deformation in gneissic rocks around Devgadh Bariya: implications for evolution of Godhra Granite. Gondwana Res 5:401–408
Mamtani MA, Pal T, Greiling RO (2013) Kinematic analysis using AMS data from a deformed granitoid. J Struct Geol 50:119–132. https://doi.org/10.1016/j.jsg.2012.03.002
Merh SS (1995) Geology of Gujarat. Geol Soc India Publ, Bangalore, p 244
Mondal TK (2018) Evolution of fabric in Chitradurga granite (south India) – A study based on microstructure, anisotropy of magnetic susceptibility (AMS) and vorticity analysis. Tectonophysics 723:149–161. https://doi.org/10.1016/j.tecto.2017.12.013
Patel D, Joshi AU, Limaye MA (2016) Sequential development of microstructures in quartzites of Champaner Group, Gujarat. J Geosci Res 1(2):101–104
Rathore JS (1979) Magnetic susceptibility anisotropy in the Cambrian slate belt of North Wales and correlation with strain. Tectonophysics 53:83–97
Sen K, Mamtani MA (2006) Magnetic fabric, shape preferred orientation and regional strain in granitic rocks. J Struct Geol 1870–1882
Srikarni C, Das S (1996) Stratigraphy and sedimentation history of Champaner Group, Gujarat. J Indian Assoc Sedim 15:93–108
Tarling DH, Hrouda F (1993) The magnetic anisotropy of rocks. Chapman and Hall, London
Acknowledgements
Authors are thankful to Prof. Manish A. Mamtani for providing unconditional support to carry out AMS analysis at Department of Geology and Geophysics, Indian Institute of Technology (IIT), Kharagpur, West-Bengal. Authors are also grateful to Prof. L. S. Chamyal, (Former Head, Department of Geology, The M. S. University of Baroda, Vadodara) for providing necessary facilities. Authors are grateful to Prof. T. K. Biswal, IITB, for inviting to contribute in IGC 2020 special volume and handling the manuscript. We are also thankful to anonymous reviewer for providing valuable suggestions.
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Joshi, A.U., Limaye, M.A. (2020). Anisotropy of Magnetic Susceptibility (AMS) Studies on Quartzites of Champaner Group, Upper Aravallis: An Implication to Decode Regional Tectonics of Southern Aravalli Mountain Belt (SAMB), Gujarat, Western India. In: Biswal, T., Ray, S., Grasemann, B. (eds) Structural Geometry of Mobile Belts of the Indian Subcontinent. Society of Earth Scientists Series. Springer, Cham. https://doi.org/10.1007/978-3-030-40593-9_9
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