Origin and tectonic significance of the metamorphic rocks associated with the Darvel Bay Ophiolite, Sabah, Malaysia

Abstract

Banded hornblende gneiss, foliated amphibolite, hornblende, chlorite and siliceous schist form lenses in an 8 km wide belt within the Darvel Bay Ophiolite Complex. Foliation in the belt is generally steep to vertical, striking parallel to the trend of the belt and lineations are sub-horizontal. Mineral and geochemical studies show that the metamorphic rocks represent banded and isotropic gabbros, plagiogranites, doleritic and basaltic dykes, basaltic volcanics and cherts formed at a spreading ridge in a supra-subduction zone environment, which were deformed at high temperatures but low pressures along a transform fault. Incorporation of supracrustal cherts indicates that the transform extended for hundreds of kilometres between spreading centres. Garnet pyroxenites and amphibolites found as clasts in Miocene volcanic agglomerates formed at high pressures, and temperatures are interpreted as derived from a metamorphic sole underlying the complex, formed during subduction of ocean crust and the emplacement of the ophiolite complex on Sabah.

Dolerites of the Woodlark Basin (Papuan Peninsula, New Guinea): A geochemical record of the influence of a neighbouring subduction zone

“…On one hand, Brooks and Tegner (2001) point out that the Leg 180 dolerites have trace element compositions similar to Ontong-Java Plateau basalts, and suggest that they are therefore related to an intraplate magmatism derived from an enriched mantle source. On the other hand, this analogy is not fully supported by previous studies (Jenner, 1981;Davies and Jacques, 1984;Permana, 1998;Monnier et al, 1995Monnier et al, , 1999Monnier et al, , 2000Omang and Barber, 1996;Yumul et al, 1997; as well as by our new geochemical data arguing for a discrete arc-related magma influence. Indeed, the presence of weak Nb and Zr anomalies in most samples (Fig.…”

“…Most of the ophiolites in this area display a geochemical signature typical of back-arc magmas onto the arc to fore-arc sequences (Jenner, 1981;Davies and Jacques, 1984;Permana, 1998;Monnier et al, 1995Monnier et al, , 1999Monnier et al, , 2000Omang and Barber, 1996;Yumul et al, 1997; suggesting that they correspond to oceanic crusts generated in a supra-subduction zone (Monnier et al, 1999;Pubellier et al, 2004). These previous geochemical data have been used to restore the Cainozoic regional tectonic setting in SE Asia.…”

“…The role of subduction zones in the genesis of several Cainozoic South East Asia ophiolites has been largely evoked since the 1980s (Jenner, 1981;Davies and Jacques, 1984;Permana, 1998;Monnier et al, 1995Monnier et al, , 1999Monnier et al, , 2000Omang and Barber, 1996;Yumul et al, 1997;.…”

Tertiary stratigraphy and basin evolution, southern Sabah (Malaysian Borneo)

“…However, most of the metamorphic rocks would have had a basic protolith (Hall and Wilson, 2000) and the granitic rocks, which are of very small volume (Hutchison et al, 2000) could represent arc plutonic rocks intruded into an older ophiolitic basement. Omang and Barber (1996) suggest that the Sabah ophiolite has an island arc chemical signature and the complex can be envisaged as forearc or backarc fragments (Hutchison et al, 2000) accreted in supra-subduction zone and arc setting where the continental fragments were also accreted (Tongkul, 1991;Hutchison et al, 2000;Hall and Wilson, 2000). The presence of ophiolite detritus in the younger, Eocene formations provides evidence that uplift and erosion of the ophiolitic terrane occurred in the latest Cretaceous or earliest Paleogene (Hutchison, 1992;Omang and Barber, 1996).…”

“…They are part of an ophiolite complex which extends further east to the Segama and Darvel Bay areas and also outcrops in central Sabah in the Telupid and BiduBidu Hills. The complex has been described by Reinhard and Wenk (1951), Fitch (1955), Dhonau and Hutchison (1966), Koopmans (1967) and Omang and Barber (1996) and comprises hornblende schists, gneisses, and ultramafic rocks (peridotites and serpentinites). The top part of the ophiolite complex is represented by the Chert -Spilite Formation made up of pillow basalt, banded chert and turbiditic sandstone.…”