TY - JOUR
T1 - Aenigmetites from the Ilímaussaq intrusion, south Greenland
T2 - Chemistry and petrological implications
AU - Larsen, Lotte Melchior
PY - 1977/10/15
Y1 - 1977/10/15
N2 - Aenigmatite in the Ilímaussaq intrusion shows a variety of textural relations to the other mafic minerals and an unusual range in chemical compositions. The saturated and oversaturated rocks contain zoned aenigmatities with Ca, Al, Fe2+-rich cores coexisting with katophorite, and near-ideal Ti-aenigmatite rims coexisting with arfvedsonite and aegirine. The aenigmatite substitutions are outlined, and the varying chemistry discussed. A no-oxide field seems to have existed in the (log fO2, T) space for the undersaturated magma, and an arfvedsonite-aenigmatite oxygen buffer equilibrium is suggested for the coexisting Fe3+-rich aenigmatite and katophorite. This buffer was later invalidated by the stabilisation of aegirine, whereby the Fe3+-aenigmatite component broke down, causing extensive recrystallisation into near-ideal Ti-aenigmatite.
AB - Aenigmatite in the Ilímaussaq intrusion shows a variety of textural relations to the other mafic minerals and an unusual range in chemical compositions. The saturated and oversaturated rocks contain zoned aenigmatities with Ca, Al, Fe2+-rich cores coexisting with katophorite, and near-ideal Ti-aenigmatite rims coexisting with arfvedsonite and aegirine. The aenigmatite substitutions are outlined, and the varying chemistry discussed. A no-oxide field seems to have existed in the (log fO2, T) space for the undersaturated magma, and an arfvedsonite-aenigmatite oxygen buffer equilibrium is suggested for the coexisting Fe3+-rich aenigmatite and katophorite. This buffer was later invalidated by the stabilisation of aegirine, whereby the Fe3+-aenigmatite component broke down, causing extensive recrystallisation into near-ideal Ti-aenigmatite.
UR - http://www.scopus.com/inward/record.url?scp=0001665932&partnerID=8YFLogxK
U2 - 10.1016/0024-4937(77)90002-0
DO - 10.1016/0024-4937(77)90002-0
M3 - Article
AN - SCOPUS:0001665932
VL - 10
SP - 257
EP - 270
JO - Lithos
JF - Lithos
SN - 0024-4937
IS - 4
ER -