Santanu,
We interpreted spinel-orthopyroxene symplectites to represent
progress of the reaction olivine + high Al pyroxene = spinel + low-Al
pyroxene during cooling (Kuo & Essene, 1986). That could also produce
lamellar spinel in orthopyroxene but requires communication with matrix
olivine. Is there any evidence of Al depletion in the pyroxene around
the spinel? eric
Kuo, Lung-Chuan & Essene, E.J. (1986) Petrology of spinel harzburgite
xenoliths from the Kishb Plateau, Saudi Arabia. Contr. Mineral.
Petrol. 93, 335-346.
Quoting Santanu Kumar Bhowmik <[log in to unmask]>:
> Dear Friends,
> I am looking for literature, which has dealt with exsolution textures
> in orthopyroxene in ultramafic rocks. In olivine-bearing
> orthopyroxenite in the Central Indian Tectonic Zone, cumulus Opx
> contains abundant exsolution lamellae of green Spl, moderate Cpx of
> equant to elongate habit. Pl in addition to its occurrence as
> intercumulus phase, also occurs as thin curvilinear grains within
> Opx. These grains are optically continuous and often associated with
> fine grains of green Spl and Cpx. Is there a possibility that
> Opx-Spl-Anorthitic Pl and Cpx association be part of a complex
> symplectite, developing from breakdown of an alumious, low-Ca
> pyroxene phase? Are there reports of aluminous pigeonite in
> literature?
>
> Thanking you in advance.
>
> With warmest regards,
>
> Santanu Kumar Bhowmik
> Associate Professor
> Dept of Geology & Geophysics
> Indian Institute of Technology
> Kharagpur-721302
> India
>
>
>
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