Description of Two New Species of Termites (Isoptera : Insecta) from the Himalaya

Mukherjee, Paramita; Maiti, P. K.

doi:10.26515/rzsi/v108/i3/2008/159038

Cited by 1 publication

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“…Some asymmetric boudins are also present near the contact (Figure 3). The centre of the pluton is marked with an abundance of muscovite, whereas the biotite is concentrated dominantly along the margins (Lahoti et al, 2017; Mukherjee et al, 1998). Apatite and zircon fission‐track ages from the DG exposed along the Dhauladhar Range, suggest slow exhumation during Middle to Late Miocene, followed by acceleration during Plio‐Pleistocene (Adlakha et al, 2013).…”

Section: Geology Of the Study Areamentioning

confidence: 99%

“…However, microstructural studies of granitic rocks can facilitate the identification of magmatic or solid‐state deformation fabrics (Paterson et al, 1989; Simpson, 1985), on the basis of such features the deformation of granites can be understood. In the last few years, major attempts have been made to understand the genesis, composition, structural and tectonic setup of the Palaeozoic granites (Adlakha et al, 2013; Bhanot et al, 1974; Bhatia & Kanwar, 1980; Dhiman & Singh, 2021; Dubey et al, 2004; Jayangondaperumal et al, 2010; Kanwar & Bhatia, 1978; Lal et al, 1999; Miller et al, 2001; Mukherjee et al, 1998; Saini et al, 1998; Thakur, 1975; Tripathi et al, 2012; Walia et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Structural and geochemical studies of the Palaeozoic granites from Dalhousie region of Himachal Himalaya: Implications on petrogenesis and deformation of strongly peraluminous S‐type granites

et al. 2022

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The Palaeozoic granites forming the Dalhousie pluton occur as an elongated body intruded into the core of an antiform in Salkhala metasedimentary rocks and are referred to herein as Dalhousie granites (DG). The studied mesoscopic structures, for example, well‐developed and randomly distributed megacrysts of K‐feldspar at the core part of massif, show undeformed porphyritic nature, whereas augen along with the mylonitic foliation and parallelly aligned feldspar megacrysts are dipping towards north‐north‐east (NNE) in the marginal part. The presence of aplite veins is evidence of final stage crystallization, where these rocks rapidly crystallized from siliceous residual fluids/solutions that escaped along fractures in the granites. Moreover, the granites show intrusive as well as thrusted contact with the Chamba metamorphics. The microscopic study from the marginal parts shows the dynamic recrystallization of quartz along with the fractures filled with secondary material oriented opposite to the top‐to‐the‐SW. Whereas euhedral quartz grains with undeformed grain boundaries, compositional zoning in plagioclase, and magmatic (perthite) texture of K‐feldspar are present in the core of Dalhousie pluton. In addition, a new whole‐rock geochemical dataset of DG is presented and investigated to elucidate the petrogenesis and tectonic environment. The geochemical data shows that DG (dominantly monzogranites) are formed from a pelitic source‐derived, (molar Al2O3/CaO + Na2O + K2O > 1.1) strongly peraluminous (S‐type) calc‐alkaline magma. This magma was generated by muscovite vapour absent dehydration melting. Harker bivariate plots indicate that fractional crystallization was a dominant process during the evolution of these granites. The tectonic discrimination diagrams suggest that DG were generated in syn‐collisional setting. Exceptionally high Pb in DG occurred due to primary melt generation at low‐temperature during partial melting (low‐degree melting) of the pelitic source rock. Trace and rare earth elements characteristics, such as positive anomaly of Zr show a notable amount of zircon as one of the accumulating phases. A pronounced negative Eu anomaly (EuN/Eu* = 0.04–0.66), along with high silica content and highly varied trace element ratios in these rocks, show that these are fairly evolved granites.

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Section: Geology Of the Study Areamentioning

confidence: 99%