scholarly journals Hf-Nd isotopes from ultramafic and mafic rocks in the western Dharwar Craton, India, record early Archean mantle heterogeneity

Lithos ◽  
2021 ◽  
Vol 404-405 ◽  
pp. 106491
Author(s):  
Arathy Ravindran ◽  
Klaus Mezger ◽  
S. Balakrishnan ◽  
Jasper Berndt
Keyword(s):  
Dharwar Craton ◽  
Mantle Heterogeneity ◽  
Nd Isotopes ◽  
Mafic Rocks

scholarly journals Extreme isotopic heterogeneity in Samoan clinopyroxenes constrains sediment recycling

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jenna V. Adams ◽  
Matthew G. Jackson ◽  
Frank J. Spera ◽  
Allison A. Price ◽  
Benjamin L. Byerly ◽  
...  
Keyword(s):  
Mantle Source ◽  
Magma Mixing ◽  
Major And Trace Elements ◽  
Mantle Heterogeneity ◽  
Isotopic Data ◽  
Nd Isotopes ◽  
Isotopic Heterogeneity ◽  
Total Variability ◽  
High Silica ◽  
Insight Into

AbstractLavas erupted at hotspot volcanoes provide evidence of mantle heterogeneity. Samoan Island lavas with high 87Sr/86Sr (>0.706) typify a mantle source incorporating ancient subducted sediments. To further characterize this source, we target a single high 87Sr/86Sr lava from Savai’i Island, Samoa for detailed analyses of 87Sr/86Sr and 143Nd/144Nd isotopes and major and trace elements on individual magmatic clinopyroxenes. We show the clinopyroxenes exhibit a remarkable range of 87Sr/86Sr—including the highest observed in an oceanic hotspot lava—encompassing ~30% of the oceanic mantle’s total variability. These new isotopic data, data from other Samoan lavas, and magma mixing calculations are consistent with clinopyroxene 87Sr/86Sr variability resulting from magma mixing between a high silica, high 87Sr/86Sr (up to 0.7316) magma, and a low silica, low 87Sr/86Sr magma. Results provide insight into the composition of magmas derived from a sediment-infiltrated mantle source and document the fate of sediment recycled into Earth’s mantle.

Progressive Metamorphism of Mafic Rocks from Greenschist to Granulite Facies in the Dharwar Craton of South India

1986 ◽  
Vol 94 (2) ◽  
pp. 261-282 ◽  
Author(s):  
P. Raase ◽  
M. Raith ◽  
D. Ackermand ◽  
R. K. Lal
Keyword(s):  
South India ◽  
Granulite Facies ◽  
Dharwar Craton ◽  
Mafic Rocks

scholarly journals Petrogenesis of 3.15 Ga old Banasandra komatiites from the Dharwar craton, India: Implications for early mantle heterogeneity

2017 ◽  
Vol 8 (3) ◽  
pp. 467-481 ◽  
Author(s):  
J.M. Maya ◽  
Rajneesh Bhutani ◽  
S. Balakrishnan ◽  
S. Rajee Sandhya
Keyword(s):  
Dharwar Craton ◽  
Mantle Heterogeneity

scholarly journals O–H–Sr–Nd isotope constraints on the origin of the Famatinian magmatic arc, NW Argentina

2020 ◽  
Vol 157 (12) ◽  
pp. 2067-2080 ◽  
Author(s):  
P. Alasino ◽  
C. Casquet ◽  
C. Galindo ◽  
R. Pankhurst ◽  
C. Rapela ◽  
...  
Keyword(s):  
Metamorphic Rocks ◽  
Crustal Material ◽  
Nd Isotopes ◽  
Nd Isotope ◽  
Sierras Pampeanas ◽  
Mafic Rocks ◽  
Oxygen Isotope Exchange ◽  
Magmatic Arc ◽  
Zircon Crystallization ◽  
Major Process

AbstractWe report a study of whole-rock O–H–Sr–Nd isotopes of Ordovician igneous and metamorphic rocks exposed at different crustal palaeodepths along c. 750 km in the Sierras Pampeanas, NW Argentina. The isotope compositions preserved in the intermediate rocks (mostly tonalite) (average δ18O = +8.7 ± 0.5‰, δD = −73 ± 14‰, 87Sr/86Srt = 0.7088 ± 0.0001 and εNdt = −4.5 ± 0.6) show no major difference from those of most of the mafic rocks (average δ18O = +8 ± 0.8‰, δD = −84 ± 18‰, 87Sr/86Srt = 0.7082 ± 0.0016 and εNdt = −4 ± 1.1), suggesting that most of their magmas acquired their crustal characteristics in the mantle. The estimate of assimilation of crustal material (δ18O = +12.2 ± 1.7‰, δD = −89 ± 21‰, 87Sr/86Srt = 0.7146 ± 0.0034 and εNdt = −6.9 ± 0.7) by the tonalite is in most samples within the range 10–20%. Felsic magmas that reached upper crustal levels had isotope values (δ18O = +9.9 ± 1.5‰, δD= −76 ± 5‰, 87Sr/86Srt = 0.7067 ± 0.0010, εNdt = −3.5 ± 1.4) suggesting that they were not derived by fractionation of the contaminated intermediate magmas, but evolved from different magma batches. Some rocks of the arc, both igneous (mostly gabbro and tonalite) and metamorphic, underwent restricted interaction with meteoric fluids. Reported values of δ18O of magmatic zircons from the Famatinian arc rocks (+6 to +9‰) are comparable to our δ18O whole-rock data, indicating that pervasive oxygen isotope exchange in the lower crust was not a major process after zircon crystallization.

MAJOR AND TRACE ELEMENT GEOCHEMISTRY AND PB-ND ISOTOPES OF MAFIC DYKES, DHARWAR CRATON, INDIA

2019 ◽  
Author(s):  
Landon D. Velarde ◽  
◽  
Scott R. Miller ◽  
George D. Kamenov ◽  
Paul A. Mueller ◽  
...  
Keyword(s):  
Trace Element ◽  
Dharwar Craton ◽  
Trace Element Geochemistry ◽  
Nd Isotopes ◽  
Element Geochemistry ◽  
Mafic Dykes

Mantle source of tephritic porphyry in the Tarim Large Igneous Province constrained from Mg, Zn, Sr, and Nd isotope systematics: Implications for deep carbon cycling

2021 ◽  
Author(s):  
Weiliang Kong ◽  
Zhaochong Zhang ◽  
Zhiguo Cheng ◽  
Bingxiang Liu ◽  
M. Santosh ◽  
...  
Keyword(s):  
Oceanic Crust ◽  
Mantle Source ◽  
Large Igneous Province ◽  
Mantle Heterogeneity ◽  
Nd Isotopes ◽  
Igneous Province ◽  
Rock Suite ◽  
Sedimentary Carbonates ◽  
Tarim Large Igneous Province

The nature and source of magmatism associated with large igneous provinces (LIPs) remain disputed. Here we investigate the role of recycled materials that contributed to mantle heterogeneity in the Tarim Large Igneous Province (TLIP) in China through integrated Zn−Mg−Sr−Nd isotopes of a rare tephritic rock suite. The Sr−Nd isotopes [(87Sr/86Sr)i = 0.70368−0.70629; εNd(t) = −0.25−4.64] and δ26Mg values (−0.23‰ to −0.34‰) of the tephritic porphyries are consistent with a normal mantle origin. In contrast, the whole rock and pyroxene phenocrysts yield δ66Zn values of +0.28‰ to +0.46‰ and +0.30‰ to +0.39‰, which are slightly heavier than those of the terrestrial mantle (+0.16 ± 0.06‰) and mid-oceanic-ridge basalts (MORBs) (+0.27 ± 0.05‰). We exclude the possibility that the heavy Zn isotopes of the Wajilitag tephritic porphyries are caused by magmatic processes such as fractional crystallization and partial melting and correlate the isotopic features to the role of altered oceanic crust along with magnesite in the mantle source. The Wajilitag tephritic porphyry displays trace-element patterns similar to those of the melts from natural hornblendite, especially those of hornblendite + peridotite. Additionally, the geochemical characteristics such as enrichment in Nb and Ta, depletion in K, high TiO2, and constant Na2O/K2O ratios also suggest that the tephritic porphyries were derived from an amphibole-bearing source contributed by altered oceanic crust along with sedimentary carbonates. Our study provides insight into the contribution of subducted materials to the mantle heterogeneity beneath the TLIP and highlights the role of subduction in the deep carbon cycle and subducted slab-lithosphere-plume interaction in the generation of LIPs.

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