Geochemical characterisation of the Neoarchaean newer dolerite dykes of the Bahalda region, Singhbhum craton, Odisha, India: Implication for petrogenesis
TL;DR: In this article, the authors investigated the petrography and geochemistry of 19 NNE-SSW to NE-SW trending dolerite dykes in two sectors in the northern and southwestern part of Bahalda town, Odisha, India.
Abstract: The mafic dyke swarm, newer dolerite dykes (NDDs) intrudes the Archaean Singbhum granite of the Singhbhum craton, eastern India. The present investigation focuses on the petrography and geochemistry of 19 NNE–SSW to NE–SW trending NDDs in two sectors in the northern and south-western part of Bahalda town, Odisha, Singhbhum. Chondrite normalised rare earth element (REE) patterns show light REE (LREE) enrichment among majority of the 13 dykes while the remaining six dykes show a flat REE pattern. Critical analyses of some important trace element ratios like Ba/La, La/Sm, Nb/Y, Ba/Y, Sm/La, Th/La, La/Sm, Nb/Zr, Th/Zr, Hf/Sm, Ta/La and Gd/Yb indicate that the dolerite dykes originated from a heterogeneous spinel peridotite mantle source which was modified by fluids and melts in an arc/back arc setting. REE modelling of these dolerite dykes were attempted on LREE-enriched representative of NDD which shows that these dykes might have been generated by 5–25% partial melting of a modified spinel peridotite source which subsequently suffered around 30% fractional crystallisation of olivine, orthopyroxene and clinopyroxene. The reported age of ~2.75–2.8 Ma seems to be applicable for these dykes and this magmatism appears to be contemporaneous with major scale anorogenic granitic activity in the Singhbhum craton marking a major event of magmatic activity in eastern India.
Citations
More filters
TL;DR: In this article, the authors examined Precambrian large Igneous Provinces (LIPs) of the Indian Shield for their economic potential, including 3 proposed LIP events in the Archean and 12 LIP event during Proterozoic Mafic-ultramafic units of LIPs.
17 citations
TL;DR: In this paper, the authors report a complicated magnetic fidelity through time in Singhbhum craton, India, with new, geographically wide-spread and spatially detailed, paleomagnetic results.
9 citations
TL;DR: In this paper, dismembered, kilometer-scale slices of gabbroid and serpentinized wehrlite rocks are found emplaced within metapelites of Chaibasa Formation, belonging to the North Singhbhum Mobile Belt, India.
7 citations
TL;DR: In this paper, the authors show that the dyke swarms are coeval feeder conduits to the volcanics, and link the geophysically imaged mid Lithospheric Discontinuity to depth of metasomatised SCLM beneath the Singhbhum craton that formed ≥2800 ǫ ago.
7 citations
TL;DR: In this article , the authors reviewed the existing geochronological and geochemical data of various Precambrian mafic dyke swarms intruding in all Indian cratons, to track temporal changes in composition of the underlying subcontinental lithospheric mantle (SCLM).
2 citations
References
More filters
01 Jan 1989
TL;DR: In this article, trace-element data for mid-ocean ridge basalts and ocean island basalts are used to formulate chemical systematics for oceanic basalts, interpreted in terms of partial-melting conditions, variations in residual mineralogy, involvement of subducted sediment, recycling of oceanic lithosphere and processes within the low velocity zone.
Abstract: Summary Trace-element data for mid-ocean ridge basalts (MORBs) and ocean island basalts (OIB) are used to formulate chemical systematics for oceanic basalts. The data suggest that the order of trace-element incompatibility in oceanic basalts is Cs ≈ Rb ≈ (≈ Tl) ≈ Ba(≈ W) > Th > U ≈ Nb = Ta ≈ K > La > Ce ≈ Pb > Pr (≈ Mo) ≈ Sr > P ≈ Nd (> F) > Zr = Hf ≈ Sm > Eu ≈ Sn (≈ Sb) ≈ Ti > Dy ≈ (Li) > Ho = Y > Yb. This rule works in general and suggests that the overall fractionation processes operating during magma generation and evolution are relatively simple, involving no significant change in the environment of formation for MORBs and OIBs. In detail, minor differences in element ratios correlate with the isotopic characteristics of different types of OIB components (HIMU, EM, MORB). These systematics are interpreted in terms of partial-melting conditions, variations in residual mineralogy, involvement of subducted sediment, recycling of oceanic lithosphere and processes within the low velocity zone. Niobium data indicate that the mantle sources of MORB and OIB are not exact complementary reservoirs to the continental crust. Subduction of oceanic crust or separation of refractory eclogite material from the former oceanic crust into the lower mantle appears to be required. The negative europium anomalies observed in some EM-type OIBs and the systematics of their key element ratios suggest the addition of a small amount (⩽1% or less) of subducted sediment to their mantle sources. However, a general lack of a crustal signature in OIBs indicates that sediment recycling has not been an important process in the convecting mantle, at least not in more recent times (⩽2 Ga). Upward migration of silica-undersaturated melts from the low velocity zone can generate an enriched reservoir in the continental and oceanic lithospheric mantle. We propose that the HIMU type (eg St Helena) OIB component can be generated in this way. This enriched mantle can be re-introduced into the convective mantle by thermal erosion of the continental lithosphere and by the recycling of the enriched oceanic lithosphere back into the mantle.
19,221 citations
TL;DR: In this paper, a system was presented whereby volcanic rocks may be classified chemically as follows: Subalkaline Rocks:A.B. Tholeiitic basalt series:Tholeitic picrite-basalt; tholeiite, tholeitic andesite; dacite; rhyolite.
Abstract: A system is presented whereby volcanic rocks may be classified chemically as follows:I. Subalkaline Rocks:A. Tholeiitic basalt series:Tholeiitic picrite-basalt; tholeiite; tholeiitic andesite.B. Calc-alkali series:High-alumina basalt; andesite; dacite; rhyolite.II. Alkaline Rocks:A. Alkali olivine basalt series:(1) Alkalic picrite–basalt; ankaramite; alkali basalt; hawaiite; mugearite; benmorite; trachyte.(2) Alkalic picrite–basalt; ankaramite; alkali basalt; trachybasalt; tristanite; trachyte.B. Nephelinic, leucitic, and analcitic rocks.III. Peralkaline Rocks:pantellerite, commendite, etc.
6,269 citations
TL;DR: This article evaluated subducting sediments on a global basis in order to better define their chemical systematics and to determine both regional and global average compositions, and then used these compositions to assess the importance of sediments to arc volcanism and crust-mantle recycling, and to re-evaluate the chemical composition of the continental crust.
2,973 citations
TL;DR: Two geochemical proxies are particularly important for the identification and classification of oceanic basalts: the Th-Nb proxy for crustal input and hence for demonstrating an oceanic, non-subduction setting; and the Ti-Yb proxy, for melting depth and hence indicating mantle temperature and thickness of the conductive lithosphere as mentioned in this paper.
2,487 citations
"Geochemical characterisation of the..." refers background in this paper
...The dykes do not show significant effect of crustal contamination as indicated by the Th/Yb vs. Nb/Yb diagram (figure 11) (Pearce 2008) and some important trace element ratios like Th/La, Nb/Y, etc....
[...]
...When dolerite samples are plotted in the Th/Yb vs. Nb/Yb diagram (figure 11) (Pearce 2008), few sample plots are plotted in and around the mantle array, but most of the samples are plotted above the mantle array along a vertical to subvertical trend, indicating the involvement of a…...
[...]