Journal ArticleDOI
Boninite-like volcanic rocks in the 3.7–3.8 Ga Isua greenstone belt, West Greenland: geochemical evidence for intra-oceanic subduction zone processes in the early Earth
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In this paper, the most altered metavolcanic amphibolites (the Garbenschiefer unit) from the Central Tectonic Domain of the Isua greenstone belt are characterized by high Mg-number (060-080), MgO (7-18 wt%), Al2O3 (14-20 wt), Ni (60-645 ppm) and Cr (60−1920 ppm) contents, but low TiO2 (020-040 wt.), Zr (12-30 ppm), Y (6-14 ppmAbout:
This article is published in Chemical Geology.The article was published on 2002-04-01. It has received 692 citations till now. The article focuses on the topics: Isua Greenstone Belt & Volcanic rock.read more
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Geochemical fingerprinting of oceanic basalts with applications to ophiolite classification and the search for Archean oceanic crust
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.
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Ophiolite genesis and global tectonics: Geochemical and tectonic fingerprinting of ancient oceanic lithosphere
Yildirim Dilek,Harald Furnes +1 more
TL;DR: A review of these ideas as well as a new classification of ophiolites, incorporating the diversity in their structural architecture and geochemical signatures that results from variations in petrological, geochemical, and tectonic processes during formation in different geodynamic settings is presented in this article.
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Alteration and geochemical patterns in the 3.7–3.8 Ga Isua greenstone belt, West Greenland
Ali Polat,Albrecht W. Hofmann +1 more
TL;DR: The Isua greenstone belt has undergone heterogeneous, poly-phase post-magmatic alteration, resulting in mobilisation of many elements including LREE and Th in contrast, Nb, Ta, Ti, Zr, Y and HREE were relatively immobile during alteration processes as mentioned in this paper.
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Growth of early continental crust by partial melting of eclogite
TL;DR: Experimental evidence showing that partial melting of hydrous basalt in the eclogite facies produces granitoid liquids with major- and trace-element compositions equivalent to Archaean TTG is presented, suggesting that TTG magmatism may have taken place beneath granite-greenstone complexes developing along Archaean intraoceanic island arcs by imbricate thrust-stacking and tectonic accretion of a diversity of subduction-related terranes.
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Formation of Earth’s early Archaean continental crust
TL;DR: In contrast to most modern terrains and some late-Archaean terrains, early Archean continental crust evolved through direct melting of thick mafic crust as discussed by the authors, which does not include the development of a mantle wedge, and call this process Archaean flat-subduction.
References
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Chemical and isotopic systematics of oceanic basalt : implications for mantle composition and processes
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.
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Chemical and isotopic systematics of oceanic basalts. Implications for Mantle Composition and Processes
The continental crust: Its composition and evolution
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.
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Geochemical discrimination of different magma series and their differentiation products using immobile elements
TL;DR: In this article, the abundance and distribution of selected minor and trace elements (Ti, Zr, Y, Nb, Ce, Ga and Sc) in fresh volcanic rocks can be used to classify the differentiation products of subalkaline and alkaline magma series in a similar manner to methods using normative or major-element indices.
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Tectonic setting of basic volcanic rocks determined using trace element analyses
Julian A. Pearce,J.R. Cann +1 more
TL;DR: In this paper, the results of analyses for Ti, Zr, Y, Nb and Sr in over 200 basaltic rocks from different tectonic settings have been used to construct diagrams in which these settings can usually be identified.