Origin of metabasites from upper tectonic unit of the Lavrion area (SE Attica, Greece): Geochemical implications for dual origin with distinct provenance of blueschist and greenschist's protoliths

Baziotis, I; Mposkos, E

dc.contributor.author	Baziotis, I	en
dc.contributor.author	Mposkos, E	en
dc.date.accessioned	2014-03-01T01:36:36Z
dc.date.available	2014-03-01T01:36:36Z
dc.date.issued	2011	en
dc.identifier.issn	0024-4937	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/21354
dc.subject	Fractional crystallization	en
dc.subject	Geochemistry	en
dc.subject	Lavrion area	en
dc.subject	Metabasites	en
dc.subject.classification	Geochemistry & Geophysics	en
dc.subject.classification	Mineralogy	en
dc.subject.other	blueschist	en
dc.subject.other	chemical composition	en
dc.subject.other	chondrite	en
dc.subject.other	fractional crystallization	en
dc.subject.other	greenschist	en
dc.subject.other	low pressure	en
dc.subject.other	metabasite	en
dc.subject.other	metamorphism	en
dc.subject.other	mid-ocean ridge basalt	en
dc.subject.other	numerical model	en
dc.subject.other	protolith	en
dc.subject.other	provenance	en
dc.subject.other	trace element	en
dc.subject.other	Attica	en
dc.subject.other	Greece	en
dc.subject.other	Lavrion	en
dc.title	Origin of metabasites from upper tectonic unit of the Lavrion area (SE Attica, Greece): Geochemical implications for dual origin with distinct provenance of blueschist and greenschist's protoliths	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.lithos.2011.07.014	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.lithos.2011.07.014	en
heal.language	English	en
heal.publicationDate	2011	en
heal.abstract	The Lavrion area forms the westernmost part of the Attic-Cycladic crystalline belt (ACCB) and is built up by two tectonic units metamorphosed at HP/LT conditions. In the Upper Tectonic Unit metabasic rocks occur as greenschists and blueschists. Major and trace elements plotted against Mg# show a systematic increase in TiO2, Fe2O3*, Na2O, Zr, Y, V. La and Yb and a decrease in Al2O3. Ni and Cr with decreasing Mg#. Typically, the blueschists always exhibit a more evolved basaltic composition. The greenschists are characterized by LREE-depleted chondrite-normalized REE patterns and Zr/Nb values that range from 15 to 24. The blueschists are characterized by slightly LREE-enriched chondrite-normalized REE patterns and lower Zr/Nb ratios (6.6-11.3). Both rock types share common geochemical features like flat HFSE patterns or slight positive Nb anomalies with La/Nb<1. The protoliths of both greenschists and blueschists show that two different suites generated their protoliths and that their magmatic evolution at low pressures has also been different. The observed Zr/Nb vs. Ce/Y ratios span the compositions of greenschists and blueschists out on hyperbolae at an ideal spectrum from intermediate N-MORB to E-MORB. However, the REE patterns of the studied metabasites cannot be explained by fractional crystallization processes alone. We interpret that the protoliths of the Lavrion metabasites support a dual origin; the blueschist's protoliths are comparable to rift-related mildly alkaline basalts whereas the greenschist's protoliths probably formed as typical N-MORB at an oceanic spreading center or in an evolved back-arc basin. A melange setting with two distinct provenances of the basic protoliths is the proposed genetic model, similar to that envisioned for other parts of the ACCB, e.g. the islands of Syros, Sifnos and Tinos. (C) 2011 Elsevier B.V. All rights reserved.	en
heal.publisher	ELSEVIER SCIENCE BV	en
heal.journalName	Lithos	en
dc.identifier.doi	10.1016/j.lithos.2011.07.014	en
dc.identifier.isi	ISI:000296822900003	en
dc.identifier.volume	126	en
dc.identifier.issue	3-4	en
dc.identifier.spage	161	en
dc.identifier.epage	173	en