Geochemical Constraints on Leucogranite Magmatism in the Langtang Valley, Nepal Himalaya

Inger, S.; Harris, Nigel

doi:10.1093/petrology/34.2.345

Cited by 468 publications

(261 citation statements)

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“…Therefore, the Bomdila two-mica granites with quartz-rich compositions and plotting at decreased pressures (< 5 kbars) and low water activities in the diagram, suggest their derivation from an alumina-saturated source under waterundersaturated condition at temperatures >800 0 C. In contrast the tourmaline-granite samples cluster around a composition corresponding to minimum melt at ~3 kbar, aH 2 O ≈ 0.5. These values are consistent with thermobarometric studies of the many well-studied leucogranites from the Himalaya such as Manaslu (Guillot and others, 1991), Langtang (Inger and Harris, 1993), etc.…”

Section: State Of the Tibetan Lithospheresupporting

confidence: 89%

Proceedings of the 25th Himalaya-Karakoram-Tibet Workshop

Leech¹,

Klemperer²,

Mooney³

2010

Open-File Report

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Section: State Of the Tibetan Lithospheresupporting

confidence: 89%

Proceedings of the 25th Himalaya-Karakoram-Tibet Workshop

Leech¹,

Klemperer²,

Mooney³

2010

Open-File Report

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“…The greater increase in Rb and K compared to Ba in the Cervatos 1eucogranites is a consequence of biotite breakdown under water-undersaturated conditions, and is consistent with a pelitic parentage for these anatectic melts [Harris and Inger, 1992;Inger and Harris, 1993]. REE, Th, Zr, Y, and P are clearly controlled by accessory mineral phases in several of which they are essential constituents [Hams et al, 1992;Sawya, 1991;Weber et aI., 1985].…”

Section: ----------------mentioning

confidence: 82%

“…This tendency to lower (87Sr/R6Sr)340 and higher E : values in the Layos granites is also shown by the Cervatos type Ieucogranites, but it is not so marked in the leucosomes which are closer to the estimated protolith composition, represented by the banded migrnatite ( Figure 5). This feature has also been observed in otlier anatectic scenarios [lnger and Harris, 1993] where it been used to reject a genetic relationship between the migmatites and the closely related leucogranites, in contrast to the ideas that will be discussed in a later section.…”

Section: Layos Granitementioning

confidence: 86%

“…Isotopic homogenization during anatexis, which occurs by self-diffu sion [Baker, 1989], is rap id enough to allow isotopic homogenization of melts and restite [Ferrara et al, 1989;inger and Harris, 1993] on a meter scale in a geologically reasonable timescale. The main mineral re servoir of Sr in the granitic rocks and migmatites of the ACT is fe ldspar, with minor amounts in biotite.…”

Section: Time Of Equilibrationmentioning

confidence: 99%

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Geochemical and isotopic disequilibrium in crustal melting: An insight from the anatectic granitoids from Toledo, Spain

Barbero¹,

Villaseca²,

Rogers³

et al. 1995

J. Geophys. Res.

107

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Abstract. In the Hercynian Anatectic Complex of Toledo (ACT) the anatectic granitoids include leucogranitic leucosomes, leucogranitic massifs, and restite-rich granites. They show a broad range of initial Sr and Nd isotope ratios from 0.71 I to 0.720 and 0.51164 to 0.51203, respectively, which clearly indicate the absence of isotopic homogenization in the melts. Broadly, the ranges reflect the isotopic variation of the metapelitic protoliths. If crusta! melting occurs under water-undersaturated conditions, as is the case of the ACT, the generated melts do not isotopically and chemically equilibrate with the granulitic residuum. The preservation of heterogeneities could arise through a number of pmcesses. (1) duration of the process:in which the presence of melts with disequilibrium features, and the high solid content of several of the granites in the ACT point to a very short-lived magmatic system, (2) limited

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“…Accordingly, it appears that most of the investigated granitoids (Rb/Sr <4; Table 5) formed by vapor-present melting. Lower Rb/Sr ratios <4 suggests the participation of biotite during melt production of the granitoids [61,62]. The strong positive correlation between Zr vs Sr and TiO 2 vs Sr in the Bapa-Batié plutonic rocks (Fig.…”

Section: Petrogenesismentioning

confidence: 91%

Neoproterozoic High-K Calc-Alkaline Granitoids from Bapa-Batié, North Equatorial Fold Belt, Central Cameroon: Petrogenesis and Geodynamic Significance

Chebeu¹

2011

TOGEOJ

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Neoproterozoic granitoids of the Bapa-Batié area crop out within the Central Cameroon Shear Zone (CCSZ). They comprise four rocks: (i) granodiorite, (ii) biotite-granite, (iii) biotite-amphibole-granite, and (iv) granitic dyke. The elongated shape of the plutons and foliation striking parallel to the CCSZ point to syntectonic magma emplacement. The rocks are metaluminous, weakly peraluminous, high-K, and calc-alkaline to shoshonitic ferro-potassic, with mineralogical and geochemical characteristics of I-type granitoids. The rocks are characterized by high Ba, Sr, Zr, Rb, Sr, low Ni and Cr contents, and by variable LREE enrichment, moderate HREE fractionation with strong negative to moderate Eu anomalies (in granodiorite, biotite-granite and biotite-amphibole-granite) and moderate to significant positive Eu anomalies (in granitic enclaves). Trace element distribution patterns show that all these rocks are distinctively depleted in Nb, P, Sr and Ti relative to other trace elements and indicate that these rocks were derived from crustal protoliths. Magmatic zircon grains in these granites yielded LA-ICP-MS U-Pb ages of 600 ± 3.7 Ma and 619 ± 29 Ma. The plutonic rocks of BapaBatié area resemble other Neoproterozoic high-K calc-alkaline granites of Cameroon and also display strong similarities with high-K calc-alkaline plutons of eastern Nigeria and the Borborema Province in NE Brazil.

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Geochemical Constraints on Leucogranite Magmatism in the Langtang Valley, Nepal Himalaya

Cited by 468 publications

References 0 publications

Proceedings of the 25th Himalaya-Karakoram-Tibet Workshop

Proceedings of the 25th Himalaya-Karakoram-Tibet Workshop

Geochemical and isotopic disequilibrium in crustal melting: An insight from the anatectic granitoids from Toledo, Spain

Neoproterozoic High-K Calc-Alkaline Granitoids from Bapa-Batié, North Equatorial Fold Belt, Central Cameroon: Petrogenesis and Geodynamic Significance

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