TY - JOUR
T1 - Peridotite enclaves hosted by Mesoarchaean TTG-suite orthogneisses in the Fiskefjord region of southern West Greenland
AU - Szilas, Kristoffer
AU - Kelemen, Peter B.
AU - Bernstein, Stefan
PY - 2015/9/1
Y1 - 2015/9/1
N2 - This study presents bulk-rock major, trace, and platinum-group element data, as well as mineral chemistry for peridotites which form large enclaves (up to 500. ×. 1000. m) within Mesoarchaean orthogneisses of the Akia terrane in the Fiskefjord region, southern West Greenland. The largest peridotite body, known as Seqi, contains highly fosteritic olivine with a median Mg# of 92.6 and hosts extensive layers of chromitite, which can be traced for tens of metres with thicknesses of up to 30. cm. Thinner (<100. m thick), but extensive (up to 2000. m long) peridotite sheets are associated with coarse norite and orthopyroxenite with distinct cumulate textures in the Amikoq complex, located a few tens of kilometres south of Seqi. Intercalated amphibolites of tholeiitic basaltic composition show complementary geochemical evolution to the peridotites, consistent with igneous crystal fractionation trends. The U-shaped trace element patterns of the peridotites may either reflect the parental melt composition from which these olivine-rich rocks were derived, or alternatively this feature may be the result of melt-rock interaction. Overall, we interpret the Fiskefjord region peridotites to have formed as ultramafic cumulates derived from Archaean high-Mg, low Ca/Al magmas, although their geodynamic setting remains to be established.
AB - This study presents bulk-rock major, trace, and platinum-group element data, as well as mineral chemistry for peridotites which form large enclaves (up to 500. ×. 1000. m) within Mesoarchaean orthogneisses of the Akia terrane in the Fiskefjord region, southern West Greenland. The largest peridotite body, known as Seqi, contains highly fosteritic olivine with a median Mg# of 92.6 and hosts extensive layers of chromitite, which can be traced for tens of metres with thicknesses of up to 30. cm. Thinner (<100. m thick), but extensive (up to 2000. m long) peridotite sheets are associated with coarse norite and orthopyroxenite with distinct cumulate textures in the Amikoq complex, located a few tens of kilometres south of Seqi. Intercalated amphibolites of tholeiitic basaltic composition show complementary geochemical evolution to the peridotites, consistent with igneous crystal fractionation trends. The U-shaped trace element patterns of the peridotites may either reflect the parental melt composition from which these olivine-rich rocks were derived, or alternatively this feature may be the result of melt-rock interaction. Overall, we interpret the Fiskefjord region peridotites to have formed as ultramafic cumulates derived from Archaean high-Mg, low Ca/Al magmas, although their geodynamic setting remains to be established.
U2 - 10.1016/j.grj.2015.03.003
DO - 10.1016/j.grj.2015.03.003
M3 - Journal article
SN - 2214-2428
VL - 7
SP - 22
EP - 34
JO - GeoResJ
JF - GeoResJ
M1 - 7
ER -