A Report on a Biotite-Calcic Hornblende Geothermometer

• Published in: Acta geologica Sinica (Beijing) Vol. 76; no. 1; pp. 126 - 131
• Main Authors: Chunming, WU, Yusheng, PAN, Kaiyi, WANG, Jian, ZHANG
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.03.2002
• Subjects: application; biotite-calcic; biotite-calcic hornblende geothermometer; calibration; error; geothermometer; hornblende; random; random error
• ISSN: 1000-9515; 1755-6724
• DOI: 10.1111/j.1755-6724.2002.tb00078.x

This paper presents a biotite-calcic hornblende geothermometer which was empirically calibrated based on the garnet-biotite geothermometer and the garnet-plagioclase-hornblende-quartz geobarometer, in the ranges of 560 800°C (T) and 0.26?1.4 Gpa (P) using the data of metadolerite, amphibolite, metagabbro, and metapelite collected from the literature. Biotite was treated as symmetric Fe-Mg-AlVI-Ti quaternary solid solution, and calcic hornblende was simplified as symmetric Fe-Mg binary solid solution. The resulting thermometer may rebuild the input garnet-biotite temperatures well within an uncertainty of 50°C. Errors of 0.2 Gpa for input pressure, along with analytical errors of 5% for the relevant mineral compositions, may lead to a random error of 16°C for this thermometer, so that the thermometer is almost independent of pressure estimates. The thermometer may clearly discriminate different rocks of lower amphibolite, upper amphibolite and granulite facies on a high confidence level. It is assumed that there is a ferric iron content of 11.6% in biotite, and that the iron content in calcic hornblende may be calculated according to the method of Dale et al. (2000). This thermometer can be used for medium- to high-grade metabasites and metapelites.