Petrography and major elements geochemistry of microgranular enclaves and neoproterozoic granitoids of south Khasi, Meghalaya: Evidence of magma mixing and alkali diffusion

Kumar, Santosh; Pieru, Thepfuvilie

doi:10.1007/s12594-010-0106-9

Cited by 22 publications

(15 citation statements)

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“…Trace elements such as Rb, Sr, Ba, and LREE shows close fit of the observed values to that of calculated values. Calculated values of remaining elements in the spider diagram shows minor deviation to the observed hybrid rock compositions (Figure b), and such variability could be due to the diffusion and heterogeneity in mineral abundance (Kumar & Pieru, ; Kumar & Rino, ). Such close similarity of the pattern and compositions establishes the bicomponent mixing (Castro, Jesús, & Stephens, ; Renjith et al, ), responsible for the compositional variability in the study area.…”

Section: Discussionmentioning

confidence: 89%

“…These features are reported from different parts of the Bastar Craton (Kumar, Rino, & Pal, and 2004b; Kumar & Rino, ; Pandit & Panigrahi, ; Elangovan, Krishna, Vishwakarma, Hari, & Ram Mohan, ). MEs are also reported in postcollisional granitoids from Mahakoshal belt (Bora, Kumar, Yi, Kim, & Lee, ) and related to Pan‐African Orogeny in south Khasi Hills of Meghalaya Plateau (Kumar & Pieru, ; Kumar, Pieru, Rino, & Hayasaka, ; Kumar, Pieru, Rino, & Lyngdoh, ). In this study, we have systematically documented the field and petrographic features, provided the mineralogical and whole‐rock geochemical data for the ME, syn‐plutonic mafic dyke, mixed zones, and host rock from the Pithora pluton to understand the extent and nature of interaction between the felsic and mafic magmas to quantify the mixing of interacting magmas.…”

Section: Introductionmentioning

confidence: 86%

“…To quantify the extent of mixing and to constrain the nature of parent material, mixing model of Fourcade and Allègre (1981) is followed. In such models, identification of most appropriate parental end-member is the key constraint to validate the mixing (Kumar & Pieru, 2010;Kumar & Singh, 2014). Accordingly, we have chosen the average chemical compositions of five host granites (sample numbers BP17/4, 5, 6, 14, and 15) as the felsic end-member, and that of four MEs (sample numbers BP17/10, 11, 12 and 13) as the mafic end-member.…”

Section: Geochemical Evidencesmentioning

confidence: 99%

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Magma chamber processes and geodynamic implications of the Pithora pluton, Bastar Craton, Central India

et al. 2019

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The interaction between the coeval mafic and felsic magmas result in mixing, mingling, and chemical exchanges between both the end‐member magmas. We document the features relevant to the magma chamber processes and quantify the extent of mixing by means of detailed field, petrographic, mineral, and whole‐rock geochemistry from one of the less known granitic plutons from the Pithora region that forms part of the Kanker granite, Bastar Craton. The study area is composed of granite, granodiorite (mixed zone), and quartz diorite microgranular enclaves (MEs). The occurrence of syn‐plutonic mafic dykes, cuspate contact, magmatic flow textures, and hybridization suggest the coeval emplacement of end‐member magmas. Petrographic evidence such as disequilibrium textures such as resorption, quartz ocelli, and spikes in plagioclase, acicular apatites, and mafic clots are formed by magma mixing. Plagioclase from MEs and the mixed region exhibit disequilibrium textures such as normal, reverse, and oscillatory zoning suggestive of magma mixing. Whole‐rock geochemical data indicates the metaluminous to peraluminous host granites and metaluminous ME. The broadly linear trend of geochemical variation diagrams for these granitoids and MEs showcase the hybridization of two end‐member magmas. The mineral chemistry of the biotites and hornblende show subduction affinity, being further constrained by whole‐rock trace elemental systematics. The granitoids of Pithora region were formed in a subduction setting where large‐scale mantle‐ and crustal‐derived magmas were generated and subsequently mixed at crustal emplacement level.

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Section: Discussionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 86%

Section: Geochemical Evidencesmentioning

confidence: 99%

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Magma chamber processes and geodynamic implications of the Pithora pluton, Bastar Craton, Central India

et al. 2019

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“…3C) could be interpreted as micro-crystals produced by quenching, where Na atoms have been partially substituted by ion exchange K atoms at high temperature (e.g., Viswanathan, 1971;Kroll and Bambauer, 1981). K migration (diffusion coefficient ~ 2.10 -7 cm 2 /sec) from felsic to mafic magmas during mingling, before the ME undercooling, has been reported by Kumar and Pieru (2010).…”

Section: Magma Mingling Mineralogical Evidencementioning

confidence: 88%

Mineralogical and geochemical evidence of magma mingling/mixing in the Sierra de las Cruces volcanic range, Mexican Volcanic Belt

Velasco-Tapia

Rodríguez-Saavedra

Márquez

et al. 2013

Journal of Iberian Geology

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Pliocene -Pleistocene lava flows, mainly of dacitic composition, are exposed in the Sierra de las Cruces (SC) volcanic range within the Mexican Volcanic Belt (MVB).SC volcanic rocks are porphyritic, generally containing an assemblage of plagioclase + amphibole + orthopyroxene ± clinopyroxene ± quartz ± Fe-Ti oxides. Most of them exhibit diverse mineralogical and geochemical features that attest a magma mixing and mingling processes with concomitant fractional crystallization in which a small volume of hot andesite magma injects into dacitic magma. Both rock types are probably derived from partial melting of continental crust at different levels.The evidences of magma mixing and mingling include: (a) normal and sieved plagioclases in the same sample, rounded and embayed crystals, and armoured rims over the dissolved crystal surfaces; (b) subrounded, vesicular magmatic enclaves, ranging from a few millimeters to ~20 centimeters in size, with plagioclase + orthopyroxene + amphibole + quartz ± olivine ± Fe-Ti-oxides assemblage; (c) mineral chemistry evidence such as crystals with reaction rims or heterogeneous plagioclase compositions (inverse and oscillatory zoning or normally and inversely zoned crystals) in the same sample; and (d) elemental geochemical variations and trace-element ratio more akin to magma mixing and to some extent diffusion process.These andesitic enclaves could be considered as portions of the intermediate magma that did not mix completely (mingling) with the felsic host lavas, confirming the major role of magma mixing and mingling processes in the overall evolution of the MVB 148

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“…In turn, these tex tural fea tures are re garded as ev i dence of the magma mixing /min gling pro cess for the gen e sis of the DBG. The higher con tents of CaO, MgO and Fe 2 O 3 (t) cor re spond ing to a greater num ber of mafic min er als in the MMEs, sug gest that they are de rived from hot ter and rel a tively more mafic melts than the host rocks (Kumar and Pieru, 2010). DIFFUSION AND CHEMICAL EXCHANGE Best (1982) high lighted that dif fu sion of at oms or mol e cules is a spon ta ne ous pro cess which oc curs due to dif fer ent con centra tions of en ergy or com po si tion in the solid, liq uid and gas phases.…”

Section: Geochemistrymentioning

confidence: 95%

Geochemical and fractal analysis of enclaves in the Dehe-Bala intrusion, (Northwestern Iran): a new concept in the interpretation of the crust–mantle interaction process

Gharamohammadi

Kananian

Eliassi

2019

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Geo chem i cal and fractal anal y sis of en claves in the Dehe-Bala in tru sion, (North west ern Iran): a new con cept in the in ter pre ta tion of the crust-man tle in ter ac tion pro cess Gharamohammadi, Z., Kananian, A., Eliassi, M., 2019. Geo chem i cal and fractal anal y sis of en claves in the Dehe-Bala in trusion, (North west ern Iran): a new con cept in the in ter pre ta tion of the crust-man tle in ter ac tion pro cess. Geo log i cal Quar terly, 63 (3): 505-521, doi: 10.7306/gq.1481 As so ci ate ed i tor: Wojciech Granoszewski The Dehe-Bala in tru sion is one of the re mark able in tru sions of granodiorite rocks with I-type af fin ity and abun dant mafic microgranular en claves (MMEs) in the Buin Zahra area, Qazvin, Iran. The MMEs, com posed of diorite and quartz-monzodiorites, are hap haz ardly wide spread in the granodiorites. The Dehe-Bala Granodiorites (DBG) usu ally are char ac ter ized by high con tents of SiO 2 (64.2-66.9), Na 2 O (3-3.23), K 2 O (3.49-4), Mg# 4.84 and Th/Ta ra tio (»7.9). In compar i son to the DBG, the MMEs can be dis tin guished by their lower value of SiO 2 (52.8-58.2), K 2 O (1.4-3.8) and higher Mg# (0.4-0.46). All these char ac ter is tics show a dif fer ent com po si tion of the DBG and MMEs, more im por tantly, can ar gue in favor of a magma mix ing/min gling or i gin in the DBG. The en rich ment in to tal REEs and HFSEs in the MMEs clearly re flects a marked diffusional pro cess from the fel sic to mafic magma that could have been achieved by chem i cal ex change dur ing the magma mix ing/min gling pro cess. The fractal di men sions (D box ) of MMEs dif fer from 1.14 to 1.29 with the high est fre quency at 1.29. The tex tural het er o ge ne ity and geo chem i cal fea tures com bined with high D box val ues in the MMEs com pared with the DBG show lower de grees of mix ing/min gling be tween man tle-de rived mafic and lower crust-de rived fel sic mag mas.Fig . 1A -sim pli fied map of tec tonic zones of the Zagros Orogenic Belt, Urumieh-Dokhtar Mag matic As sem blage (UDMA), Sanandaj-Sirjan Zone (SSZ), Zagros Fault Thrust Belt (ZFTB); B -sim pli fied geo log i cal map of the DBG in south -west Buin Zahra (af ter Eghlimi, 2000)

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Petrography and major elements geochemistry of microgranular enclaves and neoproterozoic granitoids of south Khasi, Meghalaya: Evidence of magma mixing and alkali diffusion

Cited by 22 publications

References 52 publications

Magma chamber processes and geodynamic implications of the Pithora pluton, Bastar Craton, Central India

Magma chamber processes and geodynamic implications of the Pithora pluton, Bastar Craton, Central India

Mineralogical and geochemical evidence of magma mingling/mixing in the Sierra de las Cruces volcanic range, Mexican Volcanic Belt

Geochemical and fractal analysis of enclaves in the Dehe-Bala intrusion, (Northwestern Iran): a new concept in the interpretation of the crust–mantle interaction process

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