Viscosities of magmatic silicate liquids; an empirical method of prediction

Shaw, Herbert R.

doi:10.2475/ajs.272.9.870

Cited by 958 publications

(567 citation statements)

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“…At high viscosity ratios, finger-like patterns are generated and they usually enhance mixing processes between the lowviscosity mafic magma and the high-viscosity felsic magma. The viscosity ratio for the two interacting magmas in the proposed model has been calculated assuming different crystal percentages and pressure of 2000 MPa (Shaw, 1972;Bottinga & Weil, 1972). Under the worst conditions, that is, with a crystalfree mafic magma and 50 % crystallized felsic magma, the viscosity ratio is only about 3 × 10 2 .…”

Section: A Qmzdmentioning

confidence: 99%

Petrogenetic and tectonic inferences from the study of the Mt Cer pluton (West Serbia)

et al. 2010

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-The Mt Cer Pluton, Serbia, is a complex laccolith-like intrusion (∼ 60 km 2 ), situated along the junction between the southern Pannonian Basin and northern Dinarides. It intrudes Palaeozoic metamorphic rocks causing weak to strong thermal effects. Based on modal and chemical compositions, four rock-types can be distinguished: (1) metaluminous I-type quartz monzonite/quartz monzodiorite (QMZD); (2) peraluminous S-type two-mica granite (TMG), which intrudes QMZD; (3) Stražanica granodiorite/quartz monzonite (GDS); and (4) isolated mafic enclaves (ME), found only in QMZD. 40 K-39 Ar dating and geological constraints indicate that the main quartz monzonite/quartz monzodiorite body of Mt Cer was emplaced not later than 21 Ma, whereas the emplacement ages of the Stražanica granodiorite/quartz monzonite and two-mica granites are estimated at around 18 and 16 Ma, respectively. The Mt Cer pluton is similar to the Mt Bukulja pluton, some 80 km southwestwards. Genesis of QMZD cannot be interpreted by fractional crystallization coupled with mixing or assimilation. It is best explained by a convection-diffusion process between mantle-derived minette/leucominette magmas and GDS-like magmas followed by two end-member magma mixing. The composition of GDS rocks suggests that GDS-like magmas could have formed by melting of lower crustal lithologies similar to amphibolite/metabasalts. The geochemistry of TMG is reproduced by an Assimilation/Fractional Crystallization model with a ratio of rate of assimilation to rate of fractional crystallization of 0.4, using the compositions of the least evolved TMG of the Bukulja pluton and adjacent metamorphic rocks as proxies for the parental magma and contaminant, respectively. The origin and evolution of the Mt Cer and adjacent Mt Bukulja plutons provide new constraints on the Tertiary geodynamics of the northern Dinarides-southern Pannonian region. The quartz monzonite/quartz monzodiorite is interpreted as a result of the Oligocene post-collisional Dinaride orogen-collapse, which included a limited lithosphere delamination, small-scale mantle upwelling, and melting of the lower crust. By contrast, the two-mica granite magmas formed through melting in shallower crustal levels during the extensional collapse in the Pannonian area.

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Section: A Qmzdmentioning

confidence: 99%

Petrogenetic and tectonic inferences from the study of the Mt Cer pluton (West Serbia)

et al. 2010

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“…Melt viscosities were calculated for reported rock compositions from the CY-1/1A drill holes, using the method of Shaw [23] (Fig. 5).…”

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

confidence: 99%

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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“…The pre-eruptive apparent viscosities of the four analysed samples were between log 10 5.37 Pa.s and log 10 10.02 Pa.s, after Giordano et al (2006) and between log 10 4.81 Pa.s and log 10 8.27 Pa.s, after Shaw (1972). Including the effect of the phenocrysts gave effective viscosities between log 10 5.0 Pa.s and log 10 8.57 Pa.s.…”

Section: Viscosity Estimatesmentioning

confidence: 75%