Constraints on the formation of geochemically variable plagiogranite intrusions in the Troodos Ophiolite, Cyprus

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• 作者：Sarah Freund (1)
  Karsten M. Haase (1)
  Manuel Keith (1)
  Christoph Beier (1)
  Dieter Garbe-Sch?nberg (2)
  
• 关键词：Magma evolution ; Tonalite ; Trondhjemite ; Crust formation ; Fractional crystallisation
• 刊名：Contributions to Mineralogy and Petrology
• 出版年：2014
• 出版时间：February 2014
• 年：2014
• 卷：167
• 期：2
• 全文大小：2,345 KB
• 作者单位：Sarah Freund (1)
  Karsten M. Haase (1)
  Manuel Keith (1)
  Christoph Beier (1)
  Dieter Garbe-Sch?nberg (2)
  
  1. GeoZentrum Nordbayern, Universit?t Erlangen-Nürnberg, Schlossgarten 5, 91054, Erlangen, Germany
  2. Institute of Geosciences, Universit?t Kiel, Ludewig-Meyn-Str. 10, 24118, Kiel, Germany
  
• ISSN：1432-0967

文摘

The geochemistry and petrology of tonalitic to trondhjemitic samples (n?=?85) from eight different plagiogranite intrusions at the gabbro/sheeted dyke transition of the Troodos Ophiolite were studied in order to determine their petrogenetic relationship to the mafic plutonic section and the lava pile. The plagiogranitic rocks have higher SiO2 contents than the majority of the glasses of the Troodos lava pile, but lie on a continuation of the chemical trends defined by the extrusive rocks, indicating that the shallow intrusions generally represent crystallised magmas. We define three different groups of plagiogranites in the Troodos Ophiolite based on different incompatible element contents and ratios. The first and most common plagiogranite group has geochemical similarities to the tholeiitic lavas forming the lavas and sheeted dyke complex in the Troodos crust, implying that these magmas formed at a spreading axis. The second plagiogranite group occurs in one intrusion that is chemically related to late-stage and off-axis boninitic lavas and dykes. One intrusion next to the Arakapas fault zone consists of incompatible element-enriched plagiogranites which are unrelated to any known mafic crustal rocks. The similarities of incompatible element ratios between plagiogranites, lavas and mafic plutonic rocks, the continuous chemical trends defined by plagiogranites and mafic rocks, as well as incompatible element modelling results, all suggest that shallow fractional crystallisation is the dominant process responsible for formation of the felsic magmas.