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Article: The Ayia Varvara Formation of SW Cyprus: A product of complex collisional tectonics
Title | The Ayia Varvara Formation of SW Cyprus: A product of complex collisional tectonics |
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Authors | |
Issue Date | 1992 |
Publisher | Elsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/tecto |
Citation | Tectonophysics, 1992, v. 212 n. 3-4, p. 193-211 How to Cite? |
Abstract | The Ayia Varvara Formation is a wedge of amphibole schists and intercalated metasediments within the intensely deformed pre-upper Maastrichtian volcanosedimentary Mamonia Complex. All contacts are steep faults against Upper Triassic transitional to alkaline lavas with reefoidal limestones, subalkaline depleted Troodos-type lavas, and serpentinised harzburgite. Ophiolite-related metamorphics are believed to have been formed by dynamothermal processes, beneath young oceanic crust during emplacement. Characteristically, such rocks might be expected to show a decrease of metamorphic grade away from the contact. Mineral analyses from the Ayia Varvara metamorphics, however, show no systematic variations that would indicate a metamorphic gradient. Hornblende remains generally calcic and of tschermakitic hornblende composition with an almost complete substitution of Mg and Fe 2+, suggesting disequilibrium. Plagioclase is essentially albitic and remains so for a distance of some 800 m from the harzburgite contact. Trace element analyses of the amphibolites and surrounding extrusives define four lava types. Types 1-3 are transitional to alkaline intraplate lavas believed to be remnants of intraoceanic islands and atolls. Type 4-lavas are extremely depleted in the HFS elements and are very similar to the Arakapas transform-fault lavas. The amphibolites have, in part, a trace-element geochemistry that is close to mid-ocean ridge basalts (MORB), a type that has not previously been recorded from Cyprus. The small area around Ayia Varvara records a long and complicated tectonic history that provides an insight into the evolution and emplacement of the Troodos ophiolite. The Mamonia Complex is interpreted as a passive margin sequence with intra-oceanic islands that was accreted onto a Late Cretaceous north-dipping subduction zone. Suprasubduction spreading produced the Troodos ophiolite and associated fracture zones. Spreading and subduction ceased in the late Maastrichtian when the newly-formed Troodos crust underwent a 90° anticlockwise rotation which juxtaposed Mamonia and Troodos (Arakapas) fracture zone rocks along arcuate, steep, strike-slip faults. At least some of the Ayia Varvara metamorphic rocks most likely represent Triassic oceanic crust and sediments metamorphosed during subduction by the overriding young Troodos crust. © 1992. |
Persistent Identifier | http://hdl.handle.net/10722/178193 |
ISSN | 2023 Impact Factor: 2.7 2023 SCImago Journal Rankings: 1.117 |
ISI Accession Number ID |
DC Field | Value | Language |
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dc.contributor.author | Malpas, J | en_US |
dc.contributor.author | Xenophontos, C | en_US |
dc.contributor.author | Williams, D | en_US |
dc.date.accessioned | 2012-12-19T09:43:21Z | - |
dc.date.available | 2012-12-19T09:43:21Z | - |
dc.date.issued | 1992 | en_US |
dc.identifier.citation | Tectonophysics, 1992, v. 212 n. 3-4, p. 193-211 | en_US |
dc.identifier.issn | 0040-1951 | en_US |
dc.identifier.uri | http://hdl.handle.net/10722/178193 | - |
dc.description.abstract | The Ayia Varvara Formation is a wedge of amphibole schists and intercalated metasediments within the intensely deformed pre-upper Maastrichtian volcanosedimentary Mamonia Complex. All contacts are steep faults against Upper Triassic transitional to alkaline lavas with reefoidal limestones, subalkaline depleted Troodos-type lavas, and serpentinised harzburgite. Ophiolite-related metamorphics are believed to have been formed by dynamothermal processes, beneath young oceanic crust during emplacement. Characteristically, such rocks might be expected to show a decrease of metamorphic grade away from the contact. Mineral analyses from the Ayia Varvara metamorphics, however, show no systematic variations that would indicate a metamorphic gradient. Hornblende remains generally calcic and of tschermakitic hornblende composition with an almost complete substitution of Mg and Fe 2+, suggesting disequilibrium. Plagioclase is essentially albitic and remains so for a distance of some 800 m from the harzburgite contact. Trace element analyses of the amphibolites and surrounding extrusives define four lava types. Types 1-3 are transitional to alkaline intraplate lavas believed to be remnants of intraoceanic islands and atolls. Type 4-lavas are extremely depleted in the HFS elements and are very similar to the Arakapas transform-fault lavas. The amphibolites have, in part, a trace-element geochemistry that is close to mid-ocean ridge basalts (MORB), a type that has not previously been recorded from Cyprus. The small area around Ayia Varvara records a long and complicated tectonic history that provides an insight into the evolution and emplacement of the Troodos ophiolite. The Mamonia Complex is interpreted as a passive margin sequence with intra-oceanic islands that was accreted onto a Late Cretaceous north-dipping subduction zone. Suprasubduction spreading produced the Troodos ophiolite and associated fracture zones. Spreading and subduction ceased in the late Maastrichtian when the newly-formed Troodos crust underwent a 90° anticlockwise rotation which juxtaposed Mamonia and Troodos (Arakapas) fracture zone rocks along arcuate, steep, strike-slip faults. At least some of the Ayia Varvara metamorphic rocks most likely represent Triassic oceanic crust and sediments metamorphosed during subduction by the overriding young Troodos crust. © 1992. | en_US |
dc.language | eng | en_US |
dc.publisher | Elsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/tecto | en_US |
dc.relation.ispartof | Tectonophysics | en_US |
dc.title | The Ayia Varvara Formation of SW Cyprus: A product of complex collisional tectonics | en_US |
dc.type | Article | en_US |
dc.identifier.email | Malpas, J: jgmalpas@hku.hk | en_US |
dc.identifier.authority | Malpas, J=rp00059 | en_US |
dc.description.nature | link_to_subscribed_fulltext | en_US |
dc.identifier.scopus | eid_2-s2.0-0027064110 | en_US |
dc.identifier.volume | 212 | en_US |
dc.identifier.issue | 3-4 | en_US |
dc.identifier.spage | 193 | en_US |
dc.identifier.epage | 211 | en_US |
dc.identifier.isi | WOS:A1992JV80500001 | - |
dc.publisher.place | Netherlands | en_US |
dc.identifier.scopusauthorid | Malpas, J=7006136845 | en_US |
dc.identifier.scopusauthorid | Xenophontos, C=6701391872 | en_US |
dc.identifier.scopusauthorid | Williams, D=15756203800 | en_US |
dc.identifier.issnl | 0040-1951 | - |