age of southern granulite terrain
TRANSCRIPT
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Age and sedimentary provenance of the SouthernGranulites, South India:
U-Th-Pb SHRIMP secondary ion mass spectrometry
Alan S. Collins a,, M. Santosh b, I. Braun c, C. Clarka
a Continental Evolution Research Group, Geology & Geophysics, School of Earth and Environmental Sciences,
The University of Adelaide, Adelaide, SA 5005, Australiab Faculty of Science, Kochi University, Akebono-cho 2-5-1, Kochi 780-8520, Japan
c Mineralogisch-Petrologisches Institut, Universitat Bonn, Poppelsdorfer Schlo, 53115 Bonn, Germany
Received 4 August 2006; received in revised form 17 January 2007; accepted 29 January 2007
Abstract
Southern India lies at a junction in the Gondwana-forming orogenic belts, between the East African Orogen and the Kuunga
Orogen. It contains voluminous high-grade metasedimentary gneisses that make up an important component of the record of
collision and amalgamation of Gondwana. Here we present U-Pb Secondary Ion Mass Spectrometry (SIMS) isotopic data from
detrital zircon cores from throughout southern India that demonstrate dominant Neoarchaean to Palaeoproterozoic age components
that are incompatible with the known ages of potential southern and central Indian source regions. The original sediments to the
Trivandrum Block gneisses were deposited between1900 and515 Ma, whereas a sample from the Achancovil Unit, and possible
also a sample from the Madurai Block, were deposited in Neoproterozoic times. We speculate that these rocks broadly correlate
with southern and western Malagasy metasedimentary rocks (including the Itremo and Molo Groups) and formed an extensive basin(or basins) that lay on the west side (present orientation) of the Neoproterozoic continent Azania. In addition, metamorphic zircon
from four samples yielded an age of 513 6 Ma that is interpreted as dating high-grade metamorphism throughout much of the
Southern Granulite Terrane.
2007 Elsevier B.V. All rights reserved.
Keywords: Gondwana; SIMS U-Pb geochronology; Zircon; Southern India; Provenance; Metamorphic age
1. Introduction
The Ediacaran-Cambrian assembly of Gondwana
occurred by the collision and amalgamation of numerous
continental blocks along a number of disparate orogenic
belts (see Collins and Pisarevsky, 2005). In recent Neo-
proterozoic palaeogeographic reconstructions, India did
not amalgamate with the other Gondwanan continents
Corresponding author. Fax: +61 8 8303 3174.
E-mail address: [email protected](A.S. Collins).
until latest Neoproterozoic or Cambrian times (Torsvik
et al., 2001; Powell and Pisarevsky, 2002; Meert, 2003;
Boger and Miller, 2004; Collins and Pisarevsky, 2005).
In these reconstructions, southern India and adjacent
regions of Madagascar, Sri Lanka and Antarctica are
located at the meeting point of a number of separate
orogenic belts that formed as India, Australia, Azania,
Kalahari and Antarctica terranes collided to form Gond-
wana (Fig. 1).
Despite this key location within the Gondwana coali-
tion, and the potential of the protoliths to the high-grade
metasedimentary rocks of southern India to delineate
0301-9268/$ see front matter 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.precamres.2007.01.006
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Fig. 1. (a)Reconstructionof part of central Gondwana at530 Ma (present continental outlines reconstructed for Gondwana usingthe reconstruction
ofReeves and de Wit, 2000). The details of southern India summarised from Geological Survey of India (1994). (b) Palaeogeographic reconstructionof the Neoproterozoic continents in the Gondwana fit of Reeves and de Wit (2000) highlighting the location of the present study (after Collins
and Pisarevsky, 2005). Achan: Achancovil shear zone; Az: Azania; Congo: Congo/Tanzania/Bangweulu Block; Ir: Irumide Belt; KKPT: Karur-
Kamban-Painavu-Trichur isotopic boundary after Ghosh et al. (2004); MB: Madurai Block; PCSS: Palghat-Cauvery shear zone system after Chetty
et al. (2003); Ruker: Ruker Terrane of the southern Prince Charles mountains, Antarctica; Tanz: Tanzania craton; TB: Trivandrum Block; Ubende:
Ubende belt; Us: Usagaran belt. Locations of samples discussed in this paper are illustrated.
the shapes of the colliding continents and constrain
the collisional history, very little is known about their
age, or provenance. Recent work on metasedimentary
rocks from southern and central Madagascar (adjacent
to southern India in GondwanaFig. 1a) has shown
how the U-Pb isotopic information locked up in the
cores of detrital zircon grains can not only constrain
the age of metasedimentary rocks, but can also help
unravel the locations of sediment source regions and
the sites of suture zones (Collins et al., 2003b; Cox
et al., 2004; Fitzsimons and Hulscher, 2005). In this
contribution we examine the U-Th-Pb isotopic record
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preserved in detrital zircon grains from metasedimentary
rocks of the Indian Southern Granulite Belt to constrain
the age of deposition of the protoliths and examine the
age-provenance record preserved in the zircon cores.
2. Geological framework
Southern India (Fig. 1a), south of the Archaean/
Palaeoproterozoic Dharwar craton, consists of Palaeo-
proterozoic (Peucat et al., 1993) orthogneisses, metased-
imentary rocks, and charnockites that continue as far
south as the Palghat-Cauvery shear zone system (Drury
and Holt, 1980; Drury et al., 1984; Chetty, 1996; Chetty
et al., 2003). The >100 km wide, crust-cutting (Reddy
et al., 2003a), Palghat-Cauvery system of anastomos-
ing shear zones, also known as the Cauvery shear zone
(Chetty et al., 2003; Chetty and Bhaskar Rao, 2006),cuts migmatitic mafic gneisses, and high-pressure gran-
ulites (Bhaskar Rao et al., 1996; Srikantappa et al.,
2003; Shimpo et al., 2006; Collins et al., in press).
The Madurai and Trivandrum Blocks (Harris et al.,
1994) lie south of the Palghat-Cauvery shear zone sys-
tem, separated from each other by the Achancovil shear
zone, an enigmaticstructure with a pronounced magnetic
(Rajaram et al., 2003) and seismic anomaly (Rajendra
Prasad et al., 2006). Both the Madurai and Trivandrum
Blocks were extensively deformed and metamorphosed
to granulite-facies during the Neoproterozoic (Bartlett
et al., 1998; Braun et al., 1998; Braun and Kriegsman,
2003; Santosh et al., 2003, 2005a; Braun and Brocker,
2004).
Geochronological information from the Madurai and
Trivandrum Blocks of southern India consist of sepa-
rate studies using Sm/Nd data (Harris et al., 1994, 1996;
Jayananda et al., 1995; Bhaskar Rao et al., 1996, 2003;
Meiner et al., 2002), Rb/Sr data (Bhaskar Rao et al.,
1996, 2003), electron-probe U-Th-Pb data (Braun et al.,
1998; Santosh et al., 2003, 2005a,b, 2006a,b), single zir-
con 207Pb-206Pb data (Jayananda et al., 1995; Bartlett et
al., 1998; Ghosh et al., 2004) and reconnaissance ther-mal ionisation U-Pb zircon data (Soman et al., 1995). To
date, the only ion microprobe studies have been under-
taken by Ghosh et al. (2004). These data have broadly
indicated the age of igneous protoliths and highlighted
the Neoproterozoic age of high-grade metamorphism,
but have not shed much light on the age of the protoliths
to the extensive metasedimentary rocks found through-
out the region. Here, we present new U-Th-Pb ion-probe
data, obtained using the Sensitive High Resolution Ion
MicroProbe (SHRIMP), from both the Trivandrum and
Madurai Blocks.
3. Analytical techniques
Zircon grains were separated from crushed rock sam-
ples by conventional magnetic and methylene iodide
liquid separation. Grains were handpicked and mounted
in epoxy resin discs that were coated with a thin mem-
brane of gold that produced a resistively of 1020 across the disc. The mounts were then imaged using
a CL detector fitted to a Phillips XL30 scanning elec-
tron microscope at a working distance of 15 mm and
using an accelerating voltage of 10 kV. The resulting
images (Fig. 2) highlight distortions in the crystal lat-
tice (Stevens Kalceff et al., 2000) that are related to
trace-element distribution and/or radiation damage (e.g.
Rubatto and Gebauer, 2000; Nasdala et al., 2003).
Zircon U-Th-Pb isotopic datawere collectedusing the
Sensitive High Resolution Ion Microprobe Mass Spec-
trometer (SHRIMP II)based in the John de Laeter Centreof Mass Spectrometry, Perth, Western Australia. The
sensitivity for Pb isotopes in zircon using SHRIMP II
was 18 cps/ppm/nA, the primary beam current was
2.53.0 nA and mass resolution was 5000. Correc-
tion of measured isotopic ratios for common Pb was
based on the measured 204Pb in each sample and often
represented a
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Fig.2. Cathodoluminescence images of selectedzircon grains. Ages presented as 206Pb/238U ages or, if indicatedby an asterisk, 207Pb/206Pb ages. All
errorsquoted at the1level. (A) Sample I04-01. Poorly cathodoluminescent grains with rarely preserved oscillatory-zoned detrital cores. (B) Sample
I03-18. Subhedral zircon with partial oscillatory-zoned discordant Mesoproterozoic core mantled with low Th and U brightly cathodoluminescent
Cambrian rim. (C) Sample I03-18. Three subhedral to anhedral detrital zircon grains. (D) Sample I04-04. Multiple detrital zircon grains. (E) Sample
K1/2. Detrital zircon grains with oscillatory-zoned cores partially reset during the Neoproterozoic/Cambrian. (F) Sample I03-20. Euhedral zircon
with a series of rims around a poorly cathodoluminescent Palaeoproterozoic core. The luminescent zones in the core are parallel with those in
the rims, suggesting that the rims may have formed by solid-state recrystalisation or an originally prismatic crystal. (G) Sample I03-20. Bright
cathodoluminescent Archaean oscillatory-zoned core mantled by a poorly luminescent inner rim that irregularly truncates the core. This inner rim
is in turn mantled by an oscillatory-zoned Cambrian rim. (H) Sample I03-21. Subhedral zircon with oscillatory-zoned Archaean core surrounded by
a poorly luminescent irregular metamict inner rim that is mantled with a homogenous brightly luminescent rim. (I) Sample I03-21. Late Archaean
sector zoned core mantled with a brightly luminescent homogenously luminescent rim.
preserve oscillatory zoning with bright centres and dark
margins (Fig. 2A).
4.1.2. I03-18
I03-18 is a garnet + biotite gneiss sample from a
sunken quarry directly south of the Ovari to Nan-
guneri road30 km south of Tirunelveli (N082818.6,
E774022.2) (Fig. 1a). The rock is compositional
banded and folded into open folds. Dark nebulous
orthopyroxene + quartz bearing veins and pods occur
that resemble incipient charnockite veins reported by
Santosh et al. (1990). These veins and pods commonly
follow cross-cutting felsic veins and locally inter-finger
along foliation planes. Graphite veins cut the outcrop.
Cathodoluminescent images of sectioned zircon
grains show a diverse series of morphologies and lumi-
nescence responses (Fig. 2B and C). Zircon grainsrange from subhedral prismatic morphologies with
aspect ratios of5:1 to nearly equant squat anhedral
ovoids. Many zircon grains have distinct cathodo-
luminescent cores that preserve oscillatory zoning
(Fig. 2B) and are mantled with more homogenous
rims that show up as bright (Fig. 2B) or dark
(Fig. 2C) luminescent zones. Many grains, and grain
cores, display truncated cathodoluminescent zones that,
along with the rounded nature of the grains, are
interpreted here as resulting from sedimentary abra-
sion.
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4.1.3. I04-04
This sample is of a garnet + biotite + sillimanite +
cordierite metapelite and was collected from a small hill
near the village of Thalavapuram, 1 km southwest of
Eruvadi (N082444 E773634). The rock is boudi-
naged and shows evidence of in-situ charnockitization
(Chetty and Bhaskar Rao, 2004). Braun (in Chetty andBhaskar Rao, 2004) described how this charnockitiza-
tion grades into massive garnet-bearing and garnet-poor
enderbites in adjacent outcrops. Zircon grains from this
sample are rounded and preserve complex CL patterns
(Fig.2D). Relatively bright CL cores grade outwardsinto
dark margins. Distinct rims are uncommon, but where
they exist, they are thin and luminesce brightly (Fig. 2D).
4.1.4. K1-2
K1-2 is a garnet-biotite gneiss from Mannanthala,
very close to Trivandrum. Zircon grains from this sampleare rounded and commonly preserve oscillatory-zoned
cores under CL. These zones are often truncated by the
grain margins, probably due to sedimentary abrasion
(Fig. 2E). Nebulous, homogenous, poorly luminescent
rims to some grains invade the cores forming concave
and linear salients (Fig. 2E).
4.2. Sample from the Madurai block (between the
Achancovil lineament and the Palghat-Cauvery
shear zone system)
4.2.1. I03-20
I03-20 is a quartzite sample from the hills
directly north of Ganguvarpatti village (N101030.8,
E774146.3) (Fig. 1a). The quartzite forms a promi-
nent 15m thick ridge dipping 70 towards the
south-east. The ridge can be traced at least 2 km across
the landscape. Below the quartzite band are leucocratic
gneisses with biotite pseudomorphs after garnet. Above
the quartzite are sapphirine-bearing pelites that record
peak-thermal metamorphic temperatures of >1000 C
(Mohan and Windley, 1993; Raith et al., 1997).
Zircongrains from I03-20have a variety of morpholo-gies ranging from euhedralprismatic crystals with aspect
ratios of 3:1 (Fig. 2F) to anhedral equant rounded
grains. Many crystals preserve cores, when imaged using
cathodoluminescence, with complex multiple rim tex-
tures (Fig. 2F and G). In some grains, fine luminescent
zones appear to transgress rim boundaries (e.g. ghost
zoning passing from bright inner rim to dark outer rim
in Fig. 2F). These crystals also preserve similar crystal
faces in the core as in the rim (Fig. 2F). Similar features
have been used to argue for a solid-state recrystallisa-
tion mechanism of rim formation (Hoskin and Black,
2000; Collins et al., 2004; Love et al., 2004). In many
casesthe rimspreserveoscillatory zoning thatcommonly
indicates zircon crystallisation from a melt (Corfu et al.,
2003). No granitic veins were seen in the outcrop mak-
ing it unclear whether these textures represent either: (1)
zircon crystallisation from a melt that has subsequently
migrated out of the rock; (2) zircon crystallisation from alow-volume metamorphic fluid that uncharacteristically
resulted in oscillatory zoning; or, (3) relict ghost zon-
ing of the original detrital grain that is still preserved
although isotopic and Th and U abundances have been
reset.
5. Secondary ion microscopy results (SIMS)
SIMS data are presented in Appendix B available
from the on-line version of this paper, geochronologi-
cal interpretations are presented in Figs. 35 whereas Thand U geochemical results are presented in Fig. 6.
5.1. I04-01
Fourteen zircon cores were analysed from sam-
ple I04-01. Four analyses were
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Fig. 3. U-Pb concordia plots of pre-latest Neoproterozoic analyses.
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Fig. 4. U-Pb concordia plots of Neoproterozoic-Cambrian analyses.
analysis is included, the resulting discordia curve has
an upper intercept of 529 18 Ma (2, MSWD = 1.02)
and a zero lower intercept (Fig. 4). The observation that
these analyses are predominantly low Th/U rims (Fig. 6)
lead to our interpretation that these ages date new zircon
growth during high-grade metamorphism.
The detrital cores from this sample dominantly
yield Mesoproterozoic and Palaeoproterozoic ages
(Figs. 3 and 4), but the presence of a number of10% discordant data that are interpreted as reflect-
ing Late Archaean to Palaeoproterozoic sources for the
protolith zircon grains (Figs. 3 and 5). Core analy-
ses that are
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Fig. 5. Probability density distribution plots.
three analyses yields an age of 2005 24Ma (2,
MSWD = 0.51, Fig. 3). Along with the lone analyses
of 2190 27 Ma, three Palaeoproterozoic source com-
ponents appear to be present. The >10% discordant
analyses also have a similar trimodal 207Pb/206Pb age
distribution (Fig. 5) that strengthens the suggestion that
these 1907, 2005 and 2190 Ma ages are significant
components of the source region.
A weighted mean of three concordant analyses
from sample K1-2 gives an age of 514 16Ma (2,
MSWD=2.7, Fig. 4) that is identical to the lower inter-
cept of a discordant array of detrital core analyses
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Fig. 6. Thorium and uranium geochemistry of analysed zircon grains.
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(518 32 Ma, Fig. 4). These zircons are homogenous in
CL. The coincidence of the lower intercept of the detri-
tal discordant array with new zircon growth (with Th/U
ratios 10% concordant (67%) and show that the
protolith to the sample contains zircon grains sourced
from Late Archaean and Palaeoproterozoic rocks with
major age components at 2700, 2260, 2100 and
1997 Ma (Figs. 3 and 5). One detrital core yields and
age of 695 16 Ma, which may indicate that this rock
was deposited in Neoproterozoic times. A distinct pop-
ulation of concordant zircon rims is interpreted to
date high-grade metamorphism at 508.3 9.0 Ma (2,MSWD = 1.7, Fig. 4).
6. Discussion
6.1. Th-U geochemistry of zircon grains and
processes of rim formation
The concentrations of thorium and uranium, and the
ratio of these cations, commonly vary between pro-
tolith zircon cores and zircon that formed, or was highly
altered, during a subsequent metamorphic event (Maaset al., 1992; Hoskin and Schaltegger, 2003; Collins et al.,
2004). In the samples analysed here, three relationships
between protolith zircon composition and interpreted
metamorphic zircon (either rims or homogenous zircon
interpreted as completely recrystallised pre-existing zir-
con) are seen (Fig. 6). Samples I03-18, K1-2 and I04-04
show decreased Th/U ratios from pre-metamorphic to
metamorphic zircon caused by an increase in U in the
syn-metamorphic zircon. In sample I03-20, the concen-
tration of U and Th values from core to rim does not
change dramatically, but instead covers a much more
restricted range of values. These analyses still maintaina reasonable spread of Th/U ratios (0.6-0.1).
A decrease in Th/U ratio is predicted during solid-
state recrystallisation (Hoskin and Black, 2000) of
pre-existing zircon due to greater incompatibility of the
Th ion in the zircon lattice than the smaller U ion (Maas
et al., 1992; Hoskin and Schaltegger, 2003). All sam-
ples show a broad trend of decreasing 232Th/238U with
age with distinct CL rims and unassigned analyses in all
samples except I04-01 showing lower Th232/U238 values
than core analyses (Fig. 6). The analysed samples show
that this decrease in Th232
/U238
ratio was largely due
to an absolute decrease in Th and increase in U in the
metamorphically-altered analyses (Fig. 6).
6.2. Age of metamorphism
A number of different samples have yielded data
that we interpret as providing estimates for the age ofhigh-grade metamorphismin the SouthernGranuliteTer-
rane. These data are from: (1) concordant analyses that
approximate the lower intercepts of discordant arrays
of partially reset detrital cores (I04-03 and K1-2); (2) a
discrete, concordant, population of zircon rims (sample
I03-20); and (3) the upper intercept of a slightly discor-
dant array of zircon rim analyses (I03-18). A weighted
mean of these results from individual samples yields an
age of 513 6 Ma (2, MSWD = 1.4), which is our best
estimate of the time of high-grade metamorphism. We
note that the estimates from individual samples collectedfrom throughout the Trivandrum and Madurai Blocks do
not differ in age, and therefore, there is no diachroneity
in the timing of high-grade metamorphism between the
Trivandrum and Madurai Blocks.
Ediacaran-Cambrian U-Th-Pb Electron Probe Micro-
Analysis (EPMA) monazite ages from the region have
been interpreted by a number of authors as estimates of
the timing of metamorphism. The results of the present
study are broadly consistent with the EPMA ages that
range from 610 to 470 Ma (Cenki et al., 2002; Braun
andBrocker,2004; Santosh et al., 2005a, 2006a,b)notethat the EMPA technique can not investigate the pres-
ence of common Pb or discordance in the analyses and
therefore has more inherent uncertainties than isotopic
techniques such as SIMS. The presented zircon data do
not contain evidence of an earlier Neoproterozoic high-
grade event that has been reported from EMPA monazite
studies (e.g. Braun and Appel, 2006). This may be a con-
sequence of sampling bias during preparation and in the
future could be addressed with an in-situ isotopic zircon
analytical campaign.
6.3. Age constraints of deposition
All samples contain evidence for a considerable
Palaeoproterozoic detrital input into their original sedi-
mentarymakeup(Figs.3and5), with theyoungest
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A.S. Collins et al. / Precambrian Research xxx (2007) xxxxxx 11
analyses interpreted as constraining the age of deposi-
tion to younger than 695 16 Ma, in the case of I03-20
from the Madurai Block, and 728 21 Ma, inthe case of
I03-18fromthe Achancovil unit ofBraun andKriegsman
(2003).
The samples analysed here were collected from a
large area of high-grade metasedimentary rocks andtherefore there is no necessity that the protoliths to
these rocks were deposited within the same sedimentary
system. Three samples from south of the Achancovil
shear zone (I04-01, I04-04 and K1-2) are conceivably
Palaeoproterozoic in age. Whereas the protoliths to I03-
18, from the Achancovil Unit close to the Achancovil
shear zone, and I03-20, from the central Madurai Block,
are likely to have been deposited in Neoproterozoic
times. The Achancovil Unit has younger Nd model ages
than the surrounding terranes (Nd TDm model ages of
1.4 1.3 Ga, Harris et al., 1994; Bartlett et al., 1998)that support the detrital zircon evidence that the pro-
toliths to these metasedimentary rocks were deposited
in Neoproterozoic times.
6.4. Provenance implications
There are possible Indian sources for some of the
detrital zircon grains. For example, rocks dated between
1880 and 1700 Ma are found in the Krishna province of
the Eastern Ghats (Dobmeier and Raith, 2003), zircon
xenocrysts date back to 2431 Ma and a detrital grain hasbeen recorded as having a 207Pb/206Pb age of 2747 Ma
(Shaw et al., 1997). However, no source in the Eastern
Ghats is known for the prominent 23001990 Ma peaks
in the age spectra from many of the samples (Fig. 5).
The Mesoarchaean to Neoarchaean Dharwar craton lies
directly north of the Southern Granulite Terrane and pro-
vided >3.0 Ga detritus into Dharwar-derived sediments
throughout the Proterozoic (Collins et al., 2003b). No
pre-3.0 Ga zircon ages were obtained from any sam-
ples analysed in this study. This lack of zircon detritus
that can be fingerprinted to southern India as well as
the missing Indian sources for the Palaeoproterozoicdetrital zircon grains suggests that the protoliths of these
Southern Granulite Terrane metasedimentary rocks may
be sourced from non-Indian terranes.
Madagascar lay directly west (present direction) of
India in Gondwana (Fig. 1) and contains similar high-
grade metasedimentary rocks in the south and west
of the island (Nicollet, 1983; Windley et al., 1994;
Collins et al., 2003a; Fernandez et al., 2003; Cox et al.,
2004; Fitzsimons and Hulscher, 2005; Collins, 2006).
These metasedimentary rocks comprise of two succes-
sions; one successionof probable Palaeoproterozoic age,
known as theItremo Group (Coxetal.,1998), which con-
tains Palaeoproterozoic and Neoarchaean detrital zircon
grains; a second succession of Neoproterozoic age (the
Molo Group) with Neoarchaean, Palaeoproterozoic and
Neoproterozoic detrital zircon grains (Cox et al., 2004;
Fitzsimons and Hulscher, 2005). These successions lay
adjacent to each other in Gondwana (Fig. 1a) and havebroadly similar detrital zircon recordsdominated by
Palaeoproterozoic sources that are not easily attributed
to India and havean absence of >3.0 Ga detritus. We here
suggest that Malagasy and southern Indian sequences
represent parts of the same sedimentary basins.
Both Cox et al. (2004) and Fitzsimons and Hulscher
(2005) suggested that the Itremo and Molo Groups were
sourced from eastern Africa. Eastern Africa has poten-
tial source rocks for all the age peaks derived from
southern India in this study. The Tanzanian craton and
Usagaran/Ubende and Irumide orogens contain numer-ous 2.7, 2.3 1.8 Ga granitoid rocks (Lenoir et al.,
1994; Borg and Krogh, 1999; Reddy et al., 2003b;
Sommer et al., 2003; Collins et al., 2004; Johnson
et al., 2005; de Waele et al., 2007). Mesoproterozoic
rocks dated at 1.4 Ga are found in the Kibaran belt
(Kokonyangi et al., 2004) and early/mid Neoproterozoic
magmatic rocks occur in central Madagascar (Handke et
al., 1999; Kroner et al., 2000) and the Mozambique belt
(Kroner et al., 2003).
In the palaeogeographicinterpretationpresentedhere,
the Palghat-Cauvery shear zone represents a Neopro-terozoic suture zone delineating the southern margin of
Neoproterozoic India and separating it from a south-
ern microcontinent represented by the Neoarchaean
metagranitoids exposed in the northern Madurai Block
(Fig. 1, Bhaskar Rao et al., 2003; Ghosh et al., 2004) that
is correlated with Azania.
7. Conclusions
Granulite-facies metasedimentary rocks from south-
ern India preserve detrital zircon cores that indicate
that these rocks were sourced from a predominantlyNeoarchaean to Palaeoproterozoic source region more
compatible with eastern Africa than with Peninsula
India. Two samples preserve near-concordant Neopro-
terozoic zircon cores that suggest that the Achancovil
unit, at least, was deposited between 728 21 Ma and
the age of metamorphismthe best estimate of which
comes from zircon rims that yield an age of 513 6Ma.
This 515 Ma age appears consistent across the South-
ern Granulite Terrane.
The metasedimentary rocks for the Southern Gran-
ulite Terrane are correlated with the metasedimentary
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12 A.S. Collins et al. / Precambrian Research xxx (2007) xxxxxx
rocks of southern and western Madagascar in partic-
ular, the Itremo and Molo groups and are interpreted
as a southern fragment of the Neoproterozoic continent
Azania (Collins and Pisarevsky, 2005).
Acknowledgements
The zircon analyses were carried out on the Sensitive
High-mass Resolution Ion Microprobe (SHRIMP II) at
the John de Laeter Centre for Mass Spectrometry, Perth
and operated by a consortium consisting of Curtin Uni-
versity of Technology, the Geological Survey of Western
Australia, and the University of Western Australia with
the support of the Australian Research Council. We
appreciate the assistance of Ian Fitzsimons, Peter Kinny,
Sasha Nemchin and Allen Kennedy during SHRIMP
analysis and data reduction. This manuscript contributes
to IGCP project 509 (Palaeoproterozoic SupercontinentsandGlobal Evolution).This is a contribution to Grant-in-
aid No. 17403013 to M. Santosh from the Japan Ministry
of Education, Sports, Culture, Science and Technology.
The authors thank two anonymous reviewers and the
editorial assistance of Peter Cawood for suggesting sub-
stantial improvements to the manuscript.
Appendix A. Supplementary data
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.precamres.2007.01.006.
References
Bartlett, J.M., Dougherty-Page, J.S., Harris, N.B.W., Hawkesworth,
C.J., Santosh, M., 1998. The application of single zircon evapora-
tion and model Nd ages to the interpretation of polymetamorphic
terrains: an example from the Proterozoic mobile belt of South
India. Contrib. Mineral. Petrol. 131, 181195.
Bhaskar Rao, Y.J., Chetty, T.R.K., Janardhan, A.S., Gopalan, K.,
1996. Sm-Nd and Rb-Sr ages and P-T history of the Archean-
Sittampundi and Bhavani layered meta-anorthosite complexes in
Cauvery shear zone, South-Indiaevidence for Neoproterozoic
reworking of Archean crust. Contrib. Mineral. Petrol. 125 (23),
237250.
Bhaskar Rao, Y.J., Janardhan, A.S., Vijaya Kumar, T., Narayana, B.L.,
Dayal, A.M., Taylor, P.N., Chetty, T.R.K., 2003. Sm-Nd model
ages and Rb-Sr isotope systematics of charnockites and gneisses
across the Cauvery Shear Zone,southernIndia: implications for the
Archaean-Neoproterozoic boundary in the southern granulite ter-
rain. In: Ranmakrishnan, M. (Ed.), Tectonics of Southern Granulite
Terrain, vol. 50. Geological Society of India Memoir, pp.297317.
Boger, S.D., Miller, J.M., 2004. Terminal suturing of Gondwana and
the onset of the Ross-Delamerian Orogeny: the cause and effect of
an Early Cambrian reconfiguration of plate motions. Earth Planet.
Sci. Lett. 219, 3548.
Borg, G., Krogh, T., 1999. Isotopic data of single zircons from the
Archaean Sukumaland Greenstone Belt,Tanzania. J. African Earth
Sci. 29, 310312.
Braun, I., Appel, P., 2006. U-Th-total Pb dating of monazite
from orthogneisses and their ultra-high temperature metapelitic
enclaves: implication for the multistage tectonic evolution
of the Madurai Block, southern India. Eur. J. Mineral. 18,
415427.Braun, I., Brocker, M., 2004. Monazite dating of granitic gneisses
and leucogranties from the Kerala Khondalite Belt, southern India:
implications for Late Proterozoic crustal evolution in East Gond-
wana. Int. J. Earth Sci. 93, 1322.
Braun, I., Kriegsman, L.M., 2003. Proterozoic crustal evolution of
southernmost India and Sri Lanka. In: Yoshida, M., Windley, B.,
Dasgupta, S. (Eds.), Proterozoic East Gondwana: Supercontinent
Assembly and Breakup. Special Publication of the Geological
Society, London, pp. 169202.
Braun, I., Montel, J.M., Nicollet, C., 1998. Electron microprobe dating
monazites from high-grade gneisses and pegmatites of the Kerala
Khondalite Belt, southern India. Chem. Geol. 146, 6585.
Braun, I., Raith, M., Ravindra Kumar, G.R., 1996. Dehydration-
melting phenomena in leptynitic gneisses and the generation of
leucogranites:a case study from theKerala Khondalite Belt, south-
ern India. J. Petrol. 37, 12851305.
Cenki, B., Kriegsman, L.M., Braun, I., 2002. Melt producing and melt
consuming reations in the Achankovil cordierite gneisses, South
India. J. Metamorphic Geol. 20, 543561.
Chetty, T.R.K., 1996. Proterozoic shear zones in southern gran-
ulite terrain, India. In: Santosh, M., Yoshida, M. (Eds.),
Gondwana Research Group Memoir3: The Archaean and Pro-
terozoic Terrains in Southern India within East Gondwana,
pp. 7789.
Chetty, T.R.K., Bhaskar Rao, Y.J. (Eds.), 2004. Tectonics and Evo-
lution of the Precambrian Southern Granulite Terrain, India &
Gondwanaian Correlations. International Workshop (IFW-SGT,2004).National Geophysical Research Institute, Hyderabad, India.
Chetty, T.R.K., Bhaskar Rao, Y.J., 2006. Constrictive deformation in
transpressional regime: field evidence from the Cauvery Shear
Zonem Southern Granulite Terrain, India. J. Struct. Geol. 28,
713720.
Chetty, T.R.K., Bhaskar Rao, Y.J., Narayana, B.L., 2003. A structural
cross section along Krishnagiri-Palani Corridor, Southern Gran-
ulite Terrain of India. In: Ramakrishnan, M. (Ed.), Tectonics of
Southern Granulite Terrain. Geological Society of India, Memoir
50, pp. 255278.
Collins, A.S., 2006. Madagascar and the amalgamation of Central
Gondwana. Gondwana Res. (GR Focus) 9, 316.
Collins, A.S., Clark, C., Sajeev, K., Santosh, M., Kelsey, D.E., Hand,
M. Passage through India: the Mozambique Ocean Suture, high
pressure granulites and the Palghat-Cauvery shear system. Terra
Nova, in press.
Collins, A.S.,Johnson, S., Fitzsimons, I.C.W., Powell, C.M.,Hulscher,
B., Abello, J., Razakamanana,T., 2003a. Neoproterozoic deforma-
tion in central Madagascar: a structural section through part of the
East African Orogen. In: Yoshida, M., Windley, B., Dasgupta, S.
(Eds.), Proterozoic East Gondwana: Supercontinent Assembly and
Breakup, vol. 206. Special Publication of the Geological Society,
London, pp. 363379.
Collins, A.S., Kroner, A., Fitzsimons, I.C.W., Razakamanana, T.,
2003b. Detritalfootprintof the Mozambique ocean: U/PbSHRIMP
and Pb evaporation zircon geochronology of Metasedimentary
Gneisses in Eastern Madagascar. Tectonophysics 375, 7799.
http://localhost/var/www/apps/conversion/tmp/scratch_4/dx.doi.org/10.1016/j.precamres.2007.01.006http://dx.doi.org/10.1016/j.precamres.2007.01.006http://dx.doi.org/10.1016/j.precamres.2007.01.006http://dx.doi.org/10.1016/j.precamres.2007.01.006http://dx.doi.org/10.1016/j.precamres.2007.01.006http://localhost/var/www/apps/conversion/tmp/scratch_4/dx.doi.org/10.1016/j.precamres.2007.01.006 -
7/28/2019 Age of Southern Granulite Terrain
13/14
Please cite this article in press as: Collins, A.S. et al., Age and sedimentary provenance of the Southern Granulites, South India:
U-Th-Pb SHRIMP secondary ion mass spectrometry, Precambrian Res. (2007), doi: 10.1016/j.precamres.2007.01.006
ARTICLE IN PRESS+Model
PRECAM-2771; No.of Pages14
A.S. Collins et al. / Precambrian Research xxx (2007) xxxxxx 13
Collins, A.S., Pisarevsky, S.A., 2005. Amalgamating eastern Gond-
wana: the evolution of the Circum-Indian Orogens. Earth Sci. Rev.
71, 229270.
Collins, A.S., Reddy, S.M., Buchan, C., Mruma, A., 2004. Temporal
constraints on palaeoproterozoic eclogite formation and exhuma-
tion (Usagaran Orogen, Tanzania). Earth Planet. Sci. Lett. 224,
175192.
Compston, W., Williams, I.S., Meyer, C., 1984. U-Pb geochronologyof zircons from lunar breccia 73217 using a sensitive high mass-
resolution ion microprobe. J. Geophys. Res. 89 (Supplement),
B525B534.
Corfu, F., Hanchar, J.M., Hoskin, P.W.O., Kinny, P.D., 2003. Atlas
of zircon textures. In: Hanchar, J.M., Hoskin, P.W.O. (Eds.), Zir-
con, Mineralogical Society of America, Reviews in Mineralogy,
Geochemistry, Washington, D.C., pp. 468500.
Cox, R., Armstrong, R.A., Ashwal, L.D., 1998. Sedimentology,
geochronology and provenance of the Proterozoic Itremo Group,
central Madagascar, and implications for pre-Gondwana palaeo-
geography. J. Geol. Soc., Lond. 155, 10091024.
Cox, R., Coleman, D.S., Chokel, C.B., DeOreo, S.B., Collins, A.S.,
Kroner, A., De Waele, B., 2004. Proterozoic tectonostratigraphy
and paleogeography of central Madagascar derived from detrital
zircon U-Pb age populations. J. Geol. 112, 379400.
de Waele, B., Kampunzu, A.B., Mapani, B.S.E., Tembo, F., 2007. The
Mesoproterozoic Irumide belt of Tanzania. J. African Earth Sci.
46, 3670.
Dobmeier, C.J., Raith, M.M., 2003. Crustal architecture and evolution
of theEasternGhats Belt andadjacentregionsof India.In: Yoshida,
M., Windley, B.F., Dasgupta, S. (Eds.), Proterozoic East Gond-
wana: Supercontinent Assemblyand Breakup, vol.206. Geological
Society of the Special Publication, London, pp. 145168.
Drury, S.A., Harris, N.B.W., Holt, R.W., Reeves-Smith, J., Whiteman,
R.T., 1984. Precambrian tectonics and crustal evolution in South
India. J. Geol. 92, 320.
Drury, S.A., Holt, R.W., 1980. The tectonic framework of the SouthIndian craton: a reconnaissance involving LANDSAT imagery.
Tectonophysics 65, 115.
Fernandez, A., Schreurs, G., Villa, I.M., Huber, S., Rakotondrazafy,
M., 2003. Age constraints on the tectonic evolution of the Itremo
region in Central Madagascar. Precamb. Res. 123, 87110.
Fitzsimons, I.C.W., Hulscher, B., 2005. Out of Africa: detrital
zircon provenance of central Madagascar and Neoproterozoic
terrane transfer across the Mozambique Ocean. Terra Nova 17,
224235.
Geological Survey of India, 1994. Project Vasundhara Generalised
Geological Map. Government of India.
Ghosh, J.G., de Wit, M.J., Zartman, R.E., 2004. Age and Tectonic
Evolution of Neoproterozoic Ductile Shear Zones in the South-
ern Granulite Terrain of India, With Implications for Gondwana
Studies. Tectonics, 23(TC3006), doi:10.1029/2002TC001444.
Handke, M., Tucker, R.D., Ashwal, L.D., 1999. Neoproterozoic con-
tinental arc magmatism in west-central Madagascar. Geology 27,
351354.
Harris, N.B.W., Bartlett, J.M., Santosh, M., 1996. Neodymium iso-
tope constraints on the tectonic evolution of East Gondwana. J.
Southeast Asian Earth Sci. 14, 119125.
Harris, N.B.W., Santosh, M., Taylor, P.N., 1994. Crustal evolution in
South India: constraints from Nd isotopes. J. Geol. 102, 139150.
Hinthorne, J.R., Anderson, C.A., Conrad, R.L., Lovering, J.F., 1979.
Single-grain 207Pb/206Pb and U/Pb age determinations with a
10m spatial resolution using the ion microprobe mass analyser
(IMMA). Chem. Geol. 25, 271303.
Hoskin, P.W.O., Black, L.P., 2000. Metamorphic zircon formation by
solid-state recrystallisation of protolith igneous grains. J. Meta-
morphic Geol. 18, 423439.
Hoskin, P.W.O., Schaltegger, U., 2003. The composition of zircon
and igneous and metamorphic petrogenesis. In: Hanchar, J.M.,
Hoskin, P.W.O. (Eds.), Zircon, Mineralogical Society of Amer-
ica, Reviews in Mineralogy, Geochemistry, vol. 53, Washington,
D.C., pp. 2762.Jayananda, M., Janardhan, A.S., Sivasubramanian, P., Peucat, J.J.,
1995.Geochronological and Isotopic Constraints on Granulite For-
mation in the Kodiakanal Area,Southern India. Geological Society
of India, Memoir 34, pp. 373390.
Johnson, S.P., Rivers,T.,De Waele, B.,2005.A review of theMesopro-
terozoic to early Palaeozoic magmatic and tectonothermal history
of southcentral Africa: implications for Rodinia and Gondwana.
J. Geol. Soc. Lond. 162, 433450.
Kokonyangi, J., Armstrong, R., Kampunzu, A.B., Yoshida, M., Oku-
daira, T., 2004. U-Pb zircon geochronology and petrology of
granitoids from Mitwaba (Katanga, Congo): implications for the
evolution of the Mesoproterozoic Kibaran belt. Precamb. Res. 132,
79106.
Kroner, A., Hegner, E., Collins, A.S., Windley, B.F., Brewer, T.S.,
Razakamanana,T., Pidgeon, R.T., 2000.Age and magmatichistory
of the Antananarivo block, Central Madagascar, as derived from
zircon geochronology and Nd isotopic systematics. Am. J. Sci.300,
251288.
Kroner, A., Muhongo, S., Hegner, E., Wingate, M.T.D., 2003. Single-
zircon geochronology and Nd isotopic systematics of Proterozoic
high-grade rocks form the Mozambique belt of southern Tanzania
(Masasi area): implications for Gondwana assembly. J. Geol. Soc.,
Lond. 160, 745757.
Lenoir, J.L., Liegeois, J.P., Theunissen, K., Klerkx, J., 1994. The
PalaeoproterozoicUbendianshear beltin Tanzania:geochronology
and structure. J. African Earth Sci. 19, 169184.
Love, G.J., Kinny, P.D., Friend, C.R.L., 2004. Timing of magmatismandmetamorphismin theGruinard Bayareaof theLewisian Gneiss
Complex: comparisons with the Assynt Terrane and implications
for terrane accretion. Contrib. Mineral. Petrol. 146, 620636.
Maas, R., Kinny, P.D., Williams, I.S., Froude, D.O., Compston, W.,
1992. TheEarthsoldest known crust:a geochronological and geo-
chemical study of 39004200 Ma old detrital zircons from Mt.
Narryer and Jack hills, Western Australia. Geochem. Cosmochim.
Acta 56, 12811300.
Meert, J., 2003. A synopsis of events related to theassembly of eastern
Gondwana. Tectonophysics 362, 140.
Meiner,B., Deters, P., Srikantappa,C., Kohler, H., 2002. Geochrono-
logical evolution of the Moyar, Bhavani and Palghat shear zones
of southern India: implications for east Gondwana correlations.
Precamb. Res. 114, 149175.
Mohan, A., Windley, B.F., 1993. Crustal trajectory of sapphirine-
bearing granulites from Ganguvarpatti, South India: evidence for
isothermal decompression. J. Metamorphic Geol. 15, 867878.
Nasdala, L., Zhang, M., Kempe, U., Panczer, M., Gaft, M., Andrut,
M., Plotze, M., 2003. Spectroscopic methods applied to zircon.
In: Hanchar, J.M., Hoskin, P.W.O. (Eds.), Zircon. Mineralogical
Society of America, Reviews in Mineralogy & Geochemistry, vol.
53, Washington, D.C., pp. 427467.
Nelson, D.R., 1997. Compilation of SHRIMP U-Pb Zircon
Geochronology Data, 1996. Geological Survey of Western Aus-
tralia, Record 1997/2, 189 pp.
Nicollet,C., 1983. Existencede granulites de haute pression a clinopy-
roxenegrenat dans les formations precambriennes du Vohibory
http://localhost/var/www/apps/conversion/tmp/scratch_4/dx.doi.org/10.1016/j.precamres.2007.01.006http://dx.doi.org/10.1029/2002TC001444http://dx.doi.org/10.1029/2002TC001444http://localhost/var/www/apps/conversion/tmp/scratch_4/dx.doi.org/10.1016/j.precamres.2007.01.006 -
7/28/2019 Age of Southern Granulite Terrain
14/14
Please cite this article in press as: Collins, A.S. et al., Age and sedimentary provenance of the Southern Granulites, South India:
ARTICLE IN PRESS+Model
PRECAM-2771; No.of Pages14
14 A.S. Collins et al. / Precambrian Research xxx (2007) xxxxxx
(SW de Madagascar). Comptes Rendus de lAcademie des Sci-
ences de Paris 297, 145148.
Peucat, J.J., Mahabaleshwar, B., Jayananda, M., 1993. Age of younger
tonalitic magmatism and granulitic metamorphism in the South
India transition zone (Krishnagiri area): comparison with older
Peninsular gneisses from the Gorur-Hassan area. J. Metamorph.
Geol. 11, 879888.
Powell, C.M., Pisarevsky, S.A., 2002. Late Neoproterozoic assemblyof East Gondwana. Geology 30, 36.
Raith, M., Karmakar, S., Brown, M., 1997. Ultra-high-temperature
metamorphism and multistage decompressional evolution of
sapphirine granulites from Palani Ranges, southern India. J. Meta-
morph. Geol. 15, 379399.
Rajaram, M., Harikumar, P., Brown, M., 2003. Thin magnetic crust
in the Southern Granulite Terrain. In: Ramakrishnan, M. (Ed.),
Tectonics of Southern Granulite, Terrain, Geological Society of
India Memoir 50, pp. 165176.
Rajendra Prasad, B., Behera, L., Koteswara Rao, P., 2006. A tomo-
graphic image of upper crustal structureusingP andS waveseismic
refraction data in the southern granulite terrain (SGT), India. Geo-
phys. Res. Lett. 33, L14301.
Reddy, P.R., Prasad, R.B., Vijaya Rao, V., Sain, K., Prasada Rao,
P., Khare, P., Reddy, M.S., 2003a. Deep seismic reflection and
refraction/wide-angle reflection studies along the Kuppam-Palani
transect in the southern granulite terrain of India. In: Ramakrish-
nan, M. (Ed.), Tectonics of Southern Granulite Terrain. Geological
Society of India Memoir 50, pp. 79106.
Reddy, S.M., Collins, A.S., Mruma, A., 2003b. Complex high-strain
deformation in the Usagaran Orogen, Tanzania: structural setting
of Palaeoproterozoic Eclogites. Tectonophysics 375, 101123.
Reeves, C., de Wit, M.J., 2000. Making ends meet in Gondwana:
retracing the transforms of the Indian Ocean and reconnecting
continental shear zones. Terra Nova 12, 272280.
Rubatto, D., Gebauer, D.,2000. Use of cathodoluminescence for U-Pb
zircon dating by ion microprobe: some examples from the westernAlps. In: Pagel, M., Barbin, V., Blanc, P., Ohnenstetter, D. (Eds.),
Cathodoluminescence in Geosciences.Springer-Verlag, Berlin, pp.
373400.
Santosh, M., Collins, A.S., Morimoto, T., Yokoyama,K., 2005a. Depo-
sitional constraints and age of metamorphism in southern India:
U-Pb chemical (EMPA) and isotopic (SIMS) ages from the Trivan-
drum Block. Geol. Mag. 142, 255268.
Santosh, M., Collins, A.S., Tamashiro, I., Koshimoto, S., Tsutsumi,
Y., Yokoyama, K., 2006a. The Timing of ultrahigh-temperature
metamorphism in Southern India: U-Th-Pb electron microprobe
ages from zircon and monazite in sapphirine-bearing granulites.
Gondwana Res. 10, 128155.
Santosh, M., Harris, N.B.W., Jackson, D.H., Mattey, D.P., 1990.
Dehydration and incipient charnockite formation: a phase equi-
libria and fluid inclusion study from South India. J. Geol. 98,
915926.
Santosh, M., Tagawa, M., Yokoyama, K., Collins, A.S., 2006b. U-Pb
electron probe geochronology of the Nagercoil Granulites, South-
ern India: implications for Gondwana Amalgamation. J. Asian
Earth Sci. 23, 6380.
Santosh, M., Tanaka, K., Yokoyama, K., Collins, A.S., 2005b. Late
Neoproterozoic-Cambrian felsic magmatism along transcrustalshear zones in southern India: U-Pb electron microprobe ages and
implications for the amalgamation of the Gondwana superconti-
nent. Gondwana Res. 8, 3142.
Santosh, M., Yokoyama, K., Biju-Sekhar, S., Rogers, J.J.W., 2003.
Multiple tectonothermal events in the granulite blocks of southern
India revealed from EPMA dating: implications on the history of
supercontinents. Gondwana Res. 6, 2963.
Shaw, R.K., Arima, M., Kagami, H., Fanning, C.M., Shiraishi, K.,
Motoyoshi, Y., 1997. Proterozoic events in the Eastern GhatsGran-
ulite Belt, India: evidence from Rb-Sr, Sm-Nd systematics, and
SHRIMP dating. J. Geol. 105, 645656.
Shimpo, M., Tsunogae, T., Santosh, M., 2006. First report of garnet-
corundum rocks from southern India: implications for prograde
high-pressure (eclogite-facies?) metamorphism. Earth Planet. Sci.
Lett. 242, 111129.
Soman, K., Narayanaswamy, Van Schmus, W.R., 1995. Preliminary
U-Pb zircon ages of high-grade rocks in southern Kerala, India. J.
Geol. Soc. India 45, 127136.
Sommer,H., Kroner, A., Hauzenberger, Muhongo, S., 2003. Metamor-
phic petrology and zircon geochronology of high-grade rocks from
the central Mozambique belt of Tanzania. J. Metamorph. Geol. 21,
915934.
Srikantappa, C., Srinivas, G.,Basavarajappa,H.T., Prakash Narasimha,
K.N., Basavalingu, B., 2003. Metamorphic evolution and fluid
regime in the deep continental crust andlong the N-S geotran-
sectfrom Vellar to Dharapuram, southern India. In: Ramakrishnan,
M. (Ed.), Tectonics of the Southern Granulite, Terrain, GeologicalSociety of India, Bangalore, pp. 319373.
Stevens Kalceff, M.A., Phillips, M.R., Moon, A.R., Kalceff, W.,
2000. Cathodoluminescence microcharacterisation of silicon diox-
ide polymorphs. In: Pagel, M., Barbin, V., Blanc, P., Ohnenstetter,
D. (Eds.), Cathodoluminescence in Geosciences. Springer-Verlag,
Berlin, pp. 193224.
Torsvik, T.H., Carter, L.M., Ashwal, L.D., Bhushan, S.K., Pandit,
M.K., Jamtveit, B., 2001. Rodinia refined or obscured: palaeo-
magnetism of the Malani igneous suite (NW India). Precamb. Res.
108, 319333.
Windley, B.F., Razafiniparany, A., Razakamanana, T., Ackermand, D.,
1994. Tectonic framework of the Precambrian of Madagascar and
its Gondwana connections: a review and reappraisal. Geologische
Rundschau 83, 642659.
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