Contrasted granite emplacement modes within an oblique crustal section: the Closepet Granite, South India

Moyen, Jean‐François; Nédélec, Anne; Martin, Hervé; Jayananda, M.

doi:10.1016/s1464-1895(01)00059-x

Cited by 19 publications

(6 citation statements)

References 19 publications

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“…In nature, the shape of an intrusive body reflects its emplacement mechanism [e.g., Rubin , 1993; Moyen et al , 2001]. Sheet‐like intrusive bodies, such as dikes and sills, appear to result from hydraulic fracturing [ Hubbert and Willis , 1957; Lister and Kerr , 1991; Clemens and Mawer , 1992; Rubin , 1995b].…”

Section: Interpretation and Discussionmentioning

confidence: 99%

Rise and emplacement of magma during horizontal shortening of the brittle crust: Insights from experimental modeling

et al. 2007

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[1] Magmatic activity tends to concentrate at plate margins. At divergent margins, extensional tectonics provide steep conduits for magma to reach the surface. At rapidly convergent margins, such as the Andes, one might imagine that horizontal compression prevents the rise of magma. Nevertheless, volcanoes are also common. In order to study the mechanisms by which magma rises in a compressional context, we resorted to laboratory experiments, in which a brittle crust was shortened, while magma was intruding. Our model materials were (1) cohesive fine-grained silica powder, representing brittle crust, and (2) molten low-viscosity vegetable oil, representing magma. In general, horizontal shortening and injection were coeval but independent processes. Thrust faults accommodated the shortening, while overpressured oil formed hydraulic fractures. In those experiments where there was no shortening, injection resulted in a saucer-shaped intrusive body. In the other experiments, where there was shortening, oil formed a basal sill, before rising along thrust faults. Once in place, the sill lubricated the base of the model, so that arcuate thrusts formed at the leading edge of a plateau. Uplift of the plateau promoted further intrusion of oil at depth. In general, the pattern of deformation and intrusion depended on the kinematic ratio R between rates of shortening and injection. The lengths of the basal sill and plateau increased with decreasing R. On the basis of these results, we have reexamined two natural examples of magmatic complexes, which were emplaced in compressional tectonic settings, Tromen volcano in Argentina and the Boulder Batholith of Montana.

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Section: Interpretation and Discussionmentioning

confidence: 99%

Rise and emplacement of magma during horizontal shortening of the brittle crust: Insights from experimental modeling

et al. 2007

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“…These plutons, commonly called late granodioritic or granitic plutons, were first identified by Shirey & Hanson (1984), who referred to them as Archaean sanukitoids. These rocks are now found in most Late Archaean terranes (2•9-2•5 Ga) (Shirey & Hanson 1984;Stern 1989;Stern & Hanson 1991;Smithies & Champion 1999;Moyen et al 2001bMoyen et al , 2003; they possess both modern (classical calcalkaline differentiation, similar to BADR association, high transition element contents) and Archaean (low HREE contents, strongly fractionated REE patterns, etc. .…”

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confidence: 99%

The sanukitoid series: magmatism at the Archaean–Proterozoic transition

Martin

Moyen

Rapp

2009

Earth and Environmental Science Transactions of the Royal Socie

163

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A specific type of granitoid, referred to as sanukitoid (Shirey & Hanson 1984), was emplaced mainly across the Archaean–Proterozoic transition. The major and trace element composition of sanukitoids is intermediate between typical Archaean TTG and modern arc granitoids. However, among sanukitoids, two groups can be distinguished on the basis of the Ti content of the less differentiated rocks of the suite: high- and low-Ti sanukitoids. Melting experiments and petrogenetic modelling show that they may have formed by either (1) melting of mantle peridotite previously metasomatised by felsic melts of TTG composition, or (2) by reaction between TTG melts and mantle peridotite (assimilation). Rocks of the sanukitoid suite were emplaced at the Archaean–Proterozoic boundary, possibly marking the time when TTG-dominated granitoid magmatism changed to a more modern-style, arc-dominated magmatism. Consequently, the intermediate character of sanukitoids is not only compositional but chronological. The succession of granitoid magmatism with time is integrated in a plate tectonic model where it is linked to the thermal evolution of subduction zones, reflecting the progressive cooling of Earth: (1) the Archaean Earth’s heat production was high enough to allow the production of large amounts of TTG granitoids formed by partial melting of recycled basaltic crust (‘slab melting’); (2) at the end of the Archaean, due to the progressive cooling of the Earth, the extent of slab melting was reduced, resulting in lower melt:rock ratios. In such conditions the slab melts can be strongly contaminated by assimilation of mantle peridotite, thus giving rise to low-Ti sanukitoids. It is also possible that the slab melts were totally consumed in reactions with mantle peridotite, subsequent melting of this ‘melt-metasomatised mantle’ producing the high-Ti sanukitoid magmas; (3) after 2·5 Ga, Earth heat production was too low to allow slab melting, except in relatively rare geodynamic circumstances, and most modern arc magmas are produced by melting of the mantle wedge peridotite metasomatised by fluids from dehydration of the subducted slab. Of course, such changes did not take place exactly at the same time all over the world. The Archaean mechanisms coexisted with new processes over a relatively long time period, even if they were subordinate to the more modern processes.

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“…The dextral rotation (D 4 ) after the sinistral event (D 3 ) is also identified in the study area. This dextral event possibility associated with the evolution of Clospet granite (Moyen et al, 2001).…”

Section: Structural Evolution Of Csbmentioning

confidence: 89%

Structural architecture and geological relationships in the southern part of Chitradurga Schist Belt, Dharwar craton, South India

Sreehari

Toyoshima

2020

Journal of Mineralogical and Petrological Sciences

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Detailed structural mapping in the southern part of Chitradurga Schist Belt (3.0-2.5 Ga) (CSB) distributed around the Chikkanayakanahalli-Kibbanahalli area was carried out. Sargur Group, Basement Gneiss, Bababudan Group, Chitradurga Group, and Hiriyur Group of rocks are well preserved in the investigated area. Unconformable relation between Basement Gneiss-Sargur Group and Bababudan Group is defined by oligomict conglomerate with quartzite clast and occasionally preserve granite clast. A polymictic conglomerate separates Bababudan and Chitradurga Groups; similarly, Chitradurga and Hiriyur Groups are also separated by a polymictic conglomerate. A new zone, Akkanahalli Zone, in the eastern margin of the study area is proposed which is belonging to Sargur Group. Zircon grains in the metatuff sample from this zone provide an age of 3313 ± 6 Ma. Six stages of deformation events are recognized in the study area. General trend and megascopic structures in the mapped area have resulted from the earlier two stages of deformations (D 2 and D 3). The D 2 stage structure is distinctly characterized by a fold-and-thrust belt consisting of a NNW-SSE trending fold zone sandwiched between a pair of NNW-SSE trending thrust faults dipping east. Deformation during the D 3 stage resulted in regional-scale sinistral shear zones, such as N-S striking Gadag-Mandya Shear Zone, and narrow N-S and NW trending sinistral 'echelon' shear zones. Based on our structural and field relationship it is proposed that CSB developed in an immature or failed rift setting where shallow marine sequence and shelf deposits are predominant. Sediments and volcanic rocks were unconformably deposited horizontally above Basement Gneiss and later got deformed together in a sinistral transpression setting.

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Contrasted granite emplacement modes within an oblique crustal section: the Closepet Granite, South India

Cited by 19 publications

References 19 publications

Rise and emplacement of magma during horizontal shortening of the brittle crust: Insights from experimental modeling

Rise and emplacement of magma during horizontal shortening of the brittle crust: Insights from experimental modeling

The sanukitoid series: magmatism at the Archaean–Proterozoic transition

Structural architecture and geological relationships in the southern part of Chitradurga Schist Belt, Dharwar craton, South India

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