Volcanic glass compositions of the Troodos ophiolite, Cyprus

Robinson, Paul T.; Melson, William G.; O'Hearn, Timothy; Schmincke, Hans‐Ulrich

doi:10.1130/0091-7613(1983)11<400:vgcott>2.0.co;2

Cited by 182 publications

(73 citation statements)

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“…[4,5,7,8]), but the discovery of glasses with compositions comparable to Cyprus lava whole rock compositions [6] has reduced the uncertainty associated with this question. Relative to their fresh precursors, the CY-1/ 1A lavas are enriched in K 2 O (up to 5 wt%) and depleted in Na 2 O (up to 1 wt%); depleted or enriched in CaO ( þ 6 wt%) (depending on carbonate content); and locally SiO 2 -depleted (up to 2 wt%) and MgO-enriched [26].…”

Section: Viscosity Of the Cy-1/1a Lavasmentioning

confidence: 99%

“…[6,30]), primary 'arc' and 'boninitic' lavas may have included signi¢cant magmatic H 2 O. The Sisson and Grove method is useful in such settings, because it explicitly accounts for the effect of H 2 O on magmatic temperature.…”

Section: Viscosity Of the Cy-1/1a Lavasmentioning

confidence: 99%

“…[11]) these low-and high-Ti suites correspond to the Upper and Lower Pillow Lavas as de¢ned by Bear [1], but elsewhere the stratigraphic relations are less clear due to incomplete sampling, structural complexity and poor ¢eld exposures [12]. The two suites were considered genetically independent because they appeared to be unrelated by fractional crystallization processes [6].…”

Section: Introductionmentioning

confidence: 99%

“…Subsequent alteration studies [6^8] suggest that this interpretation was incomplete and based on erroneous data [9]. Studies of volcanic glasses [6] occurring throughout the volcanic sequence allowed the division of the volcanic pile into a shallow picriteb asalt^basaltic andesite assemblage with low TiO 2 concentration, and a deeper basalt^andesite^da-cite^rhyodacite assemblage with high TiO 2 content ( s 0.85 wt% [10]). The shallow lava sequence consists of highly depleted magmas of 'boninitic' a⁄nity.…”

Section: Introductionmentioning

confidence: 99%

“…2B). Studies of the Troodos sheeted dikes showed that chemically the dikes are a close match to the shallow and deeper pillow lava sequence and the high-and low-Ti series identi¢ed in the lava glasses [6]. The low-Ti suite in the sheeted complex comprises about 20% of the dikes, which show no preferred age relationship with respect to those of the high-Ti suite [10].…”

Section: Introductionmentioning

confidence: 99%

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Melt viscosity, temperature and transport processes, Troodos ophiolite, Cyprus

Schouten

Kelemen

2002

Earth and Planetary Science Letters

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The lava section in the Troodos ophiolite, Cyprus, is chemically stratified and divided into a shallow lava sequence with low TiO 2 content and a deeper lava sequence with high TiO 2 content. We calculate the viscosity at magmatic temperature based on major element chemistry of lavas in Cyprus Crustal Study Project (CCSP) Holes CY-1 and 1A. We find that typical shallow low-Ti lavas have a magmatic viscosity that is two to three orders of magnitude lower than that of the deeper high-Ti lavas. This implies that, after eruption on-axis, Troodos low-Ti lavas would have been able to flow down the same slope faster and farther than high-Ti lavas. The calculated lava viscosity increases systematically from the lava^sediment interface to the bottom of the composite Hole CY-1/1A. This suggests that an efficient process of lava segregation by viscosity on the upper flanks of the paleo Troodos rise may have been responsible for the chemical stratification in the Troodos lava pile. Calculated magmatic temperature and molar Mg/ (Mg+Fe), or Mg#, decrease systematically down-section, while SiO 2 content increases. Correlation of Mg# in the lavas with Mg# in the underlying, lower crustal plutonic rocks sampled by CCSP Hole CY-4 shows that the shallow lavas came from a high-temperature, lower crustal magma reservoir which is now represented by high-Mg# pyroxenite cumulates, while the deeper lavas were erupted from a lower-temperature, mid-crustal reservoir which is now represented by gabbroic cumulates with lower Mg#. ß 2002 Published by Elsevier Science B.V.

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