Chemistry and mineralogy of garnet pyroxenites from Sabah, Malaysia

Morgan, Benjamin A.

doi:10.1007/bf00951337

Cited by 11 publications

(8 citation statements)

References 12 publications

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“…8c). P, T estimates from amphiboles and from garnet-pyroxene pairs in the present study (Omang 1993), and an earlier study of garnet pyroxenite from the same locality by Morgan (1974), give the conditions of formation of these rocks as T > 850°C at P > 5 kbar.…”

Section: Garnet Amphibolitesupporting

confidence: 72%

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

Omang

Barber

1996

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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.

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Section: Garnet Amphibolitesupporting

confidence: 72%

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

Omang

Barber

1996

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“…Sabah exposes the ophiolitic rocks and an Upper Cretaceous‐Cenozoic accretionary complex and intervening mélanges (Figure ). The ophiolite comprises amphibolite, ultramafics, gabbro, basaltic dykes, plagiogranites, basaltic rocks, and radiolarian chert (Asis & Jasin, ; Jasin, ; Morgan, ). Near Telupid, spilite yielded a K‐Ar age of 137.54 ± 6.88 Ma (Rangin et al, ), while the radiolarian chert yielded an Early Cretaceous (late Valinginian‐Barremian) age range (Jasin, ; Leong, ).…”

Section: Geologic Settingmentioning

confidence: 99%

Cenozoic Rotation History of Borneo and Sundaland, SE Asia Revealed by Paleomagnetism, Seismic Tomography, and Kinematic Reconstruction

Advokaat

Marshall

et al. 2018

Tectonics

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SE Asia comprises a heterogeneous assemblage of fragments derived from Cathaysia (Eurasia) in the north and Gondwana in the south, separated by suture zones representing closed former ocean basins. The western part of the region comprises Sundaland, which was formed by Late Permian‐Triassic amalgamation of continental and arc fragments now found in Indochina, the Thai Penisula, Peninsular Malaysia, and Sumatra. On Borneo, the Kuching Zone formed the eastern margin of Sundaland since the Triassic. To the SE of the Kuching Zone, the Gondwana‐derived continental fragments of SW Borneo and East Kalimantan accreted in the Cretaceous. South China‐derived fragments accreted to north of the Kuching Zone in the Miocene. Deciphering this complex geodynamic history of SE Asia requires restoration of its deformation history, but quantitative constraints are often sparse. Paleomagnetism may provide such constraints. Previous paleomagnetic studies demonstrated that Sundaland and fragments in Borneo underwent vertical axis rotations since the Cretaceous. We provide new paleomagnetic data from Eocene‐Miocene sedimentary rocks in the Kutai Basin, east Borneo, and critically reevaluate the published database, omitting sites that do not pass widely used, up‐to‐date reliability criteria. We use the resulting database to develop an updated kinematic restoration. We test the regional or local nature of paleomagnetic rotations against fits between the restored orientation of the Sunda Trench and seismic tomography images of the associated slabs. Paleomagnetic data and mantle tomography of the Sunda slab indicate that Sundaland did not experience significant vertical axis rotations since the Late Jurassic. Paleomagnetic data show that Borneo underwent a ~35° counterclockwise rotation constrained to the Late Eocene and an additional ~10° counterclockwise rotation since the Early Miocene. How this rotation was accommodated relative to Sundaland is enigmatic but likely involved distributed extension in the West Java Sea between Borneo and Sumatra. This Late Eocene‐Early Oligocene rotation is contemporaneous with and may have been driven by a marked change in motion of Australia relative to Eurasia, from eastward to northward, which also has led to the initiation of subduction along the eastern Sunda trench and the proto‐South China Sea to the south and north of Borneo, respectively.

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“…The latter rock consists of Ca–tschermakite‐rich augite and coarse garnet with a rather wide compositional range (Xpyr = 0.28–0.56, Xalm = 0.19–0.41, Xgros = 0.18–0.30, Xsps = 0.01). Garnet has kelyphitic mantles of fine‐grained amphibole, but Morgan (1974) reports there is no petrographic evidence of breakdown or exsolution of the primary clinopyroxene. Estimated P–T conditions are 850 °C ± 150 °C and 19 kbar ± 4 kbar (Morgan 1974).…”

Section: Other High‐pressure Metamorphic Rocks In the Central Indonesmentioning

confidence: 99%

“…Garnet has kelyphitic mantles of fine‐grained amphibole, but Morgan (1974) reports there is no petrographic evidence of breakdown or exsolution of the primary clinopyroxene. Estimated P–T conditions are 850 °C ± 150 °C and 19 kbar ± 4 kbar (Morgan 1974). The provenance and age(s) of the Sabah metamorphic rocks are not known.…”

Section: Other High‐pressure Metamorphic Rocks In the Central Indonesmentioning

confidence: 99%

An overview and tectonic synthesis of the pre‐Tertiary very‐high‐pressure metamorphic and associated rocks of Java, Sulawesi and Kalimantan, Indonesia

et al. 1998

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High‐pressure metamorphic rocks are widely distributed in Cretaceous accretionary complexes throughout Java, Sulawesi (formerly Celebes) and southeast Kalimantan (Indonesian Borneo). Many of these rocks occur as imbricate slices of carbonate, quartzose and pelitic schists of shallow marine or continental margin parentage, interthrust with subordinate basic schists and serpentinite. They are predominantly of low‐to‐intermediate metamorphic grade (300 < T < 550 °C; 4 < P < 12 kbar) and yield mica K–Ar radiometric ages of 110–120 Ma. Metamorphic rocks that exhibit evidence of exhumation from much greater depths (> 60 km), however, are sporadically exposed, usually as tectonic blocks, throughout the Cretaceous accretionary complexes. They include eclogite, garnet–glaucophane rock (P = 18–24 kbar, T = 580–620 °C), and jadeite–garnet–quartz (?coesite) rock (?P > 27 kbar, T = 720–760 °C) in Bantimala, southwest Sulawesi; eclogite and garnet granulite in west central Sulawesi; eclogite and jadeite‐glaucophane‐quartz rock (P ∼ 22 kbar, T ∼ 530 °C) in Luk Ulo, Central Java; and Mg–chloritoid‐bearing whiteschists (P ∼ ?18 kbar) in the Meratus Mountains, southeast Kalimantan. Garnet lherzolites from depths of > 60 km are also associated with schists in east central Sulawesi (P = 22–28 kbar, T = 1000–1100 °C), west central Sulawesi (P = 16–20 kbar, T = 1050–1100 °C); and garnet pyroxenite (P ∼ 20 kbar, T ∼ 850 °C) occurs as blocks with pyrope–kyanite amphibolite, eclogite and blueschist, within Miocene conglomerate in Sabah, northeast Borneo. Many of the metamorphic rocks were probably recrystallized in a north‐dipping subduction zone at the margin of the Sundaland craton in the Early Cretaceous. Exhumation may have been facilitated by the collision of a Gondwanan continental fragment with the Sundaland margin at ca 120–115 Ma.

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Chemistry and mineralogy of garnet pyroxenites from Sabah, Malaysia

Cited by 11 publications

References 12 publications

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

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

Cenozoic Rotation History of Borneo and Sundaland, SE Asia Revealed by Paleomagnetism, Seismic Tomography, and Kinematic Reconstruction

An overview and tectonic synthesis of the pre‐Tertiary very‐high‐pressure metamorphic and associated rocks of Java, Sulawesi and Kalimantan, Indonesia

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