Geodynamic constraints from glass geochemistry in the Troodos ophiolite

Conference contribution
(Abstract of lecture)


Publication Details

Author(s): Wölki D, Regelous M, Haase K, Beier C
Publication year: 2017


Abstract


Ophiolites represent fragments of oceanic crust formed at spreading ridges and have been used to infer on the processes at mid-ocean ridges in the past. Many ophiolites were suggested to have formed in a ‘supra-subduction zone’ environment indicated by the characteristic enrichment in fluid-soluble elements relative to Rare Earth Elements compared to mid-ocean ridge basalts (MORB). But the precise tectonic is still debated. Here, we present microanalytical measured major and trace element data along with Sr and Pb isotopes of fresh volcanic glasses from traverses through the pillow lava sequence of the Troodos ophiolite.



Glasses from the northern margin of the Troodos ophiolite display a large range in trace element and isotope composition. The range from tholeiitic basalts to andesitic and dacitic lavas that all have relatively low Pb/Ce ratios (0.13) indicating a subtle subduction zone component. They are also more depleted compared to normal depleted MORB (Sm/Yb = 0.87). The other Troodos glasses form a continuous array from less depleted tholeiitic to strongly depleted boninitic lavas (Sm/Yb = 0.24) that display greater influence from a subduction zone fluid component (Pb/Ce = 0.77). This source has subsequently been re-enriched by small degree sediment melts (high Nb/La = 2.94). Strontium and Pb isotope ratios increase with decreasing Sm/Yb and increasing Pb/Ce and Nb/La. The most depleted lavas with the highest subduction zone input occur south of the Arakapas Transform Fault suggesting that the former subduction zone was situated south of the present-day southern margin of the Troodos ophiolite. The paleo-spreading direction (east-west) was not parallel to the subduction zone and may represent a back-arc spreading ridge that propagated into arc crust. These observations seem to preclude an origin for the Troodos ophiolite during subduction initiation. Further detailed profiles through the Troodos lava pile are currently under work to test this hypothesis.



FAU Authors / FAU Editors

Beier, Christoph PD Dr.
Lehrstuhl für Endogene Geodynamik
Haase, Karsten Prof. Dr.
Lehrstuhl für Endogene Geodynamik
Regelous, Marcel PD Dr.
Geozentrum Nordbayern
Wölki, Dominic
Lehrstuhl für Endogene Geodynamik


How to cite

APA:
Wölki, D., Regelous, M., Haase, K., & Beier, C. (2017). Geodynamic constraints from glass geochemistry in the Troodos ophiolite. Paper presentation at GeoBremen2017, Bremen.

MLA:
Wölki, Dominic, et al. "Geodynamic constraints from glass geochemistry in the Troodos ophiolite." Presented at GeoBremen2017, Bremen 2017.

BibTeX: 

Last updated on 2018-08-08 at 13:23

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