Fe57 mossbauer investigation of pargasite-hastingsite series : implications for ferroan pargasite from mawat ophiolite complex. NE Iraq

Abstract EN

M&ssbauer ipectiovxipy and microprobe analysis technique* have been applied on ferroan pargasite belonging lo the subsea metamorphosed diabasic rocks of Mawat ophiolite complex, for site assignment of the Fe24 and Fe1*' in Che crystal structure.

The spectra are interpreted in terms of Fe2*1 in the M(l), M(3) and M(2) sites with quadrupole splitting, QS: 2.67-2.70,2.35-2.44 and 1.84*1.86 mm/sec respectively.

While the QS of Fe'* which normally occupies the M(2) site it 0.63-0.73 mm/sec.

As the AI2Ot and Fe20, contents in ferroan pargasite increases, reduction occurs in the values of OS for Fe5* in M( I) site, and separates the M(1) and M(3) doublets.

The residing of Fe'* iron in M(2) sites occur at low oxygen fugaity (fo^) of '12% which is independent of the chemical environment.

On the other hand, the fractional areas of the three Fe1* doublets show partial ordering as compared with previous studies.