Zirconium in rutile thermometry of the Himalayan ultrahigh-pressure eclogites and their retrogressed counterparts, Kaghan Valley, Pakistan
Journal
Lithos
Journal Volume
344-345
Pages
86-99
Date Issued
2019
Author(s)
Abstract
This study reports zirconium-in-rutile thermometry data from the Himalayan ultrahigh-pressure eclogites and their retrogressed counterparts. The Zr contents of three textural varieties of rutile i.e. matrix rutile, inclusion phase, and overgrown by ilmenite/titanite from coesite-bearing eclogites, slightly retrogressed eclogites, highly retrogressed eclogites, and amphibolites were analyzed for Zr contents using the electron probe micro-analyser. Majority of the rutile grains exhibited homogeneous chemical compositions in all the aforementioned textural varieties; however, some of grains were relatively heterogeneous. Average temperature values of 729 ¢XC, 727 ¢XC, and 706 ¢XC were obtained for the matrix, inclusion, and overgrown rutiles from UHP eclogites and of 705 ¢XC, 699 ¢XC, and 707 ¢XC for those from HP eclogites, respectively. Slightly retrogressed eclogites yielded similar average T values of 703 ¢XC, 706 ¢XC, and 706 ¢XC, respectively, whereas highly retrogressed eclogites resulted in relatively low average temperatures, ca. 690 ¢XC, 691 ¢XC, and 679 ¢XC, respectively. When compared with these eclogites, lower average T values of 672 ¢XC, 630 ¢XC, and 656 ¢XC were obtained from garnetites, and of 665 ¢XC, 658 ¢XC, and 640 ¢XC from garnet amphibolites, respectively. The relatively homogeneous Zr contents and higher temperature values from the matrix rutile in HP and UHP eclogites suggest peak or near-peak metamorphic crystallization, whereas grains with low Zr contents, yielding low temperature values, were likely to be affected by the late-stage retrogression. ? 2019 Elsevier B.V.
Subjects
Garnet-amphibolites
Himalaya
Kaghan Valley
UHP eclogites
Zr-in-rutile thermometry
SDGs
Type
journal article