| Reference Type | Journal (article/letter/editorial) |
|---|
| Title | Kornerupine breakdown reactions in paragneisses from southern Madagascar |
|---|
| Journal | Mineralogical Magazine | ISSN | 0026-461X |
|---|
| Authors | Ackermand, Dietrich | Author |
|---|
| Windley, Brian F. | Author |
| Razafiniparany, Andriantefison H. | Author |
| Year | 1991 (March) | Volume | 55 |
|---|
| Page(s) | 71-80 | Issue | 378 |
|---|
| Publisher | Mineralogical Society |
|---|
| Download URL | https://rruff.info/doclib/MinMag/Volume_55/55-378-71.pdf+ |
|---|
| DOI | doi:10.1180/minmag.1991.055.378.06Search in ResearchGate |
|---|
| Mindat Ref. ID | 1694 | Long-form Identifier | mindat:1:5:1694:4 |
|---|
|
| GUID | 175cd034-e28e-42eb-a7e5-0ee26fade0b5 |
|---|
| Full Reference | Ackermand, Dietrich, Windley, Brian F., Razafiniparany, Andriantefison H. (1991) Kornerupine breakdown reactions in paragneisses from southern Madagascar. Mineralogical Magazine, 55 (378) 71-80 doi:10.1180/minmag.1991.055.378.06 |
|---|
| Plain Text | Ackermand, Dietrich, Windley, Brian F., Razafiniparany, Andriantefison H. (1991) Kornerupine breakdown reactions in paragneisses from southern Madagascar. Mineralogical Magazine, 55 (378) 71-80 doi:10.1180/minmag.1991.055.378.06 |
|---|
| In | (1991, March) Mineralogical Magazine Vol. 55 (378) Mineralogical Society |
|---|
| Abstract/Notes | AbstractKornerupine-rich layers up to several centimetres thick with minor sillimanite, spinel, Fe oxide and ilmenite occur in a diopsidite in sillimanite-cordierite gneiss south of Beraketa (24°27′S, 46°48′E), southern Madagascar. Kornerupine, sillimanite, spinel and hematite grains up to 1 mm across have mutual polygonal boundaries indicating textural equilibrium at their crystallisation. Kornerupine has XMg 0.67–0.80 and 0.9 to 2.6 wt.% B2O3. Sillimanite contains up to 2.0 wt.% Fe2O3. Spinel is essentially (Mg,Fe2+) Al2O4 with an XMg range of 0.29–0.40 and exsolution lamellae of Fe oxide. Textural relations demonstrate two limited reactions, each confined to areas less than 500 µm across: (1) Kornerupine and spinel reacted along grain contacts to form very fine-grained tourmaline, corundum and chlorite. The replacing phases are symmetrically zoned with a central tourmaline and hematite, bordered by an aggregate of chlorite, tourmaline and corundum, followed outwards by a rim of chlorite against the kornerupine and spinel. (2) Within kornerupine grains, zoned, round aggregates consist of very fine-grained chlorite, tourmaline and corundum of different composition than in (1). They define the terminal reaction of kornerupine breakdown.Geothermobarometry indicates that the early kornerupine-bearing assemblage was stable at 7.0 kbar and 700 °C. This P-T point lies close to the retrograde, nearly isothermal trajectory defined independently by nearby sapphirine-bearing assemblages. The fine-grained aggregates formed most likely during further cooling, or by increasing water fugacity. |
|---|
These are possibly similar items as determined by title/reference text matching only.
