PETROGENESIS OF GABAL RAMEID ALKALINE RING COMPLEX, HOOTH AREA,REPUBLIC OF YEMEN

Gabal Rameid magmatic complex (~11km²) represents an excellent example of ring complex of Yemen. It is located in the southeastern part of Hooth town (NW Sana`a).
This complex emplaced within Jurassic limestone of Amran Group reflecting a narrow contact zone of pneumatolytic phase (~3.25 km²). The present work represents the first record of the ring complex in Yemen. The studied magmatic complex shows distinct concentric compositional zoning with porphyritic syenite, outer ring sheet (~2.75 km²), trachy-syenite, intermediate ring sheet (~3.5 km²) and quartz-syenite, inner ring sheet (~4.75 km²). A number of different fault styles cut across the ring structure extending (in part) to the pneumatolytic contact zone.
The field relations and petrochemical characteristics of the Gabal Rameid ring complex reflect co-magmatic nature of the entire suite, in which fractional crystallization played an important role in the evolution of the magmatic complex. On the other hands, these rocks are characteristic of intraplate environment of A-type suite evolved in three categories with multi-pulses of eplacement with an OIB-type source.