Crust–mantle interaction in the genesis of siliceous high magnesian basalts: evidence from the Early Proterozoic Dongargarh Supergroup, India
TL;DR: In this paper, the authors present chemical (XRF, INAA) and mineralogical data on a siliceous high magnesian basalts (SHMB) suite from the Early Proterozoic (2.1-2.5 Ga) Dongargarh Supergroup, Central India, the first of its kind reported from the Indian Precambrian.
About: This article is published in Chemical Geology.The article was published on 2002-07-01. It has received 27 citations till now. The article focuses on the topics: Incompatible element & Volcanic rock.
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TL;DR: In this paper, the authors reported a new finding of a boninite dyke intruded in the Amgaon gneisses of this area, which is composed of mainly pyroxenes, amphiboles and a subordinate amount of plagioclase.
Abstract: The Dongargarh Supergroup along with the basal Amgaon Gneissic Complex constitutes the northwestern part of the central Indian Bastar craton. In the present study, we report a new finding of a boninite dyke intruded in the Amgaon gneisses of this area. The dyke composed of mainly pyroxenes, amphiboles and subordinate amount of plagioclase. The higher contents of $$\hbox {SiO}_{2}$$
(51–54 wt.%), MgO (12–14 wt.%), Ni (375–473 ppm), Cr (1416–1580 ppm) and very low $$\hbox {TiO}_{2}$$
(0.2–0.4 wt.%) are consistent with the boninite nature of the dyke as well as the unevolved primary nature of the source magma. The extraordinarily high CaO content (15.97–17.7 wt.%) with higher $$\hbox {CaO/Al}_{2}\hbox {O}_{3}$$
(3.13–3.96) ratios classifies it as high-Ca boninite. The trace element ratios including Zr/Ti, Ti/V, Ti/Sc and Ti/Yb further show its geochemical similarity with the Archaean boninite. The dyke also shows negative high-field strength element (Nb, Ta and Ti) anomalies which are the characteristics of the boninite rocks reported elsewhere and along with the enriched light rare earth element pattern, it shows more affinity particularly with the northern Bastar boninite dyke. The mineralogical and geochemical similarities of the boninite dykes from the Bastar craton indicate a widespread boninitic event during the Palaeoproterozoic having a similar origin. These boninite dykes indicate the preservation of subduction-related signatures in the lithospheric mantle beneath the Bastar craton at the time of its evolution or may be during the convergence of the Bastar and Bundelkhand cratons.
4 citations
Cites background from "Crust–mantle interaction in the gen..."
...However, the low-Ti and highTi volcanics and siliceous high magnesium basalts (SHMB) are also reported from the Palaeoproterozoic Dongargarh Supergroup (Asthana et al. 1996; Sensarma et al. 2002)....
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TL;DR: In this paper, compositional peculiarities of the siliceous high-Mg series (SHMS) rocks formed at the Archean-Paleoproterozoic boundary as a function of plume activity are discussed using example of Early PaleoproTERozoic mafic volcanic rocks of the Vodlozero Domain, Fennoscandian Shield.
Abstract: Compositional peculiarities of the siliceous high-Mg series (SHMS) rocks formed at the Archean–Paleoproterozoic boundary as a function of plume activity are discussed using example of Early Paleoproterozoic mafic volcanic rocks of the Vodlozero Domain, Fennoscandian Shield. These rocks are characterized by wide variations in Mg# (from 33 to 67) and Cr contents (from 25 to 1123 ppm), LREE enrichment, and weakly negative eNd (from –0.7 to –2.9). The high Gd/Yb ratio in the primitive high-Mg rocks of the Vodlozero Domain suggests their generation from a garnet-bearing source. At the same time, their negative eNd in combination with LREE enrichment points to the crustal contamination. A new model was proposed to explain the remarkable global-scale similarity of SHMS. Such rocks can be generated by the contamination of a high-degree (30%) partial melt derived from a depleted mantle. The lower crustal sanukitoid-type rocks can be considered as a universal crustal contaminant. Modeling showed that such mixing can provide the observed narrow eNd variations in Early Paleoproterozoic volcanics. The Neoarchean sanukitoid suites, which are widespread on all cratons, presumably composed the lower crust at the beginning of the Paleoproterozoic. Therefore, this mechanism can be considered universal for the genesis of the SHMS rocks. The high- to low-Cr rock series can be produced by the fractionation of the mafic melt coupled with an insignificant crustal assimilation of felsic end members of the sanukitoid suite of the Vodlozero Domain en route to the surface, as suggested by the positive correlation of eNd with Cr and Mg#, negative correlation with Th, and slight decrease of eNd in the more evolved varieties.
3 citations
TL;DR: In this paper , the authors reported the ages and geochemistry of Paleoproterozoic granites and Khallari layered intrusion from the Dongargarh Supergroup of Bastar craton, central India.
References
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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
01 Jan 1985
TL;DR: In this paper, the authors describe the composition of the present upper crust and deal with possible compositions for the total crust and the inferred composition of lower crust, and the question of the uniformity of crustal composition throughout geological time is discussed.
Abstract: This book describes the composition of the present upper crust, and deals with possible compositions for the total crust and the inferred composition of the lower crust. The question of the uniformity of crustal composition throughout geological time is discussed. It describes the Archean crust and models for crustal evolution in Archean and Post-Archean time. The rate of growth of the crust through time is assessed, and the effects of the extraction of the crust on mantle compositions. The question of early pre-geological crusts on the Earth is discussed and comparisons are given with crusts on the Moon, Mercury, Mars, Venus and the Galilean Satellites.
12,457 citations
TL;DR: In this paper, the authors compared the relative abundances of the refractory elements in carbonaceous, ordinary, and enstatite chondritic meteorites and found that the most consistent composition of the Earth's core is derived from the seismic profile and its interpretation, compared with primitive meteorites, and chemical and petrological models of peridotite-basalt melting relationships.
10,830 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