Bulletin of the Geological Society of Malaysia, Volume 38, Dec. 1995, pp. 31 – 48
Jabatan Sains Bumi, Fakulti Sains dan Sumber Alam, Universiti Kebangsaan Malaysia Kampus Sabah, Beg Berkunci No. 62, 88996 Kota Kinabalu, Sabah
Abstract: The mantle-sequence peridotites of the Darvel Bay Ophiolite are represented predominantly by depleted harzburgites. These rocks are characterised by mineral chemistry of spinel XCr = 39, XMg = 61; olivine Fo = 90 and orthopyroxene (Opx) En = 88-90, Al2O3 – 3.4 wt.%, CaO = 1.8 wt.%), suggesting a mantle residue which has undergone a moderate to high degree of a previously depleted source (oceanic upper mantle). Composition of spinel Xcr-Opx (Al2O3) and bulk-chemistry indicate ~20% partial melting of this source. The Darvel Bay harzburgites are less depleted (refractory) mantle than the harzburgites of Oman, Papuan and Halmahera Ophiolites. The Darvel Bay harzburgites represent a supra-subduction zone (SSZ)-ophiolite type, supported by bulk-rock chemistry of TiO2 contents. The tectonic evolution model of the Darvel bay Ophiolite is much easier to explain using a model of supra-subduction zone (SSZ) ophiolite accreting new material in a forearc region.