Open AccessConditions of origin of kimberlites in West Greenland: new evidence from the Sarfartoq and Sukkertoppen regions
Author(s) -
Lotte Melchior Larsen,
Jørn G. Rønsbo
Publication year - 1993
Publication title -
rapport
Language(s) - English
Resource type - Journals
eISSN - 2597-2944
pISSN - 0418-6559
DOI - 10.34194/rapggu.v159.8219
Subject(s) - kimberlite , geology , archean , geochemistry , diamond , eclogite , geothermal gradient , proterozoic , petrology , mantle (geology) , paleontology , tectonics , chemistry , organic chemistry , subduction
Minerals in a garnet lherzolite nodule from Sarfartoq and macrocrysts in a kimberlite from the Sukkertoppen region have been analysed by microprobe. Temperatures calculated for the Sarfartoq nodule lie in the range 1110–1137°C, and pressures are estimated at greater than 50 kbar. The calculated temperature for the Sukkertoppen macrocrysts is 1309°C. Temperatures recalculated from existing data for kimberlites in the Holsteinsborg region and in SW Greenland lie in the range 1034–1078°C (40-50 kbar). The temperature variations may reflect the setting of the kimberlites in Archaean and Proterozoic terrains. Assuming a common geotherm of 40mW/m2 all the kimberlites in West Greenland originated within the diamond stability field.