Geology of north west Borneo : Sarawak Brunei and Sabah The book is a comprehensive compilation of all aspects of the geology of Northwest Borneo (Sarawak Brunei and Sabah) and the contiguous South China and Sulu Seas. The sedimentary formations are described their palaeontology tabulated and ages discussed. Stratigraphic charts illustrate their relationships across the whole region. Detailed geological maps of selected areas are accompanied by cross sections based on outcrop patterns and drilling and seismic data offshore. Palaeocurrent maps are presented and the palaeogeography for different ages described and sedimentary provenance discussed. Descriptions of the ophiolite sequences volcanic and plutonic rocks are accompanied by tables of selected chemical analyses and geochemical plots and their tectonic significance discussed. All radiometric data are tabulated and discussed. Regional structures and the predominantly Tertiary tectonics are described. In Sarawak the mountains are constructed of Upper Cretaceous to Lower Eocene greenschist facies shaly turbiditic Rajang Group uplifted before the end of the Eocene. In Sabah the Western Cordillera is constructed of Eocene to Lower Miocene sandy turbidite uplifted in the Late Miocene and Pliocene. Miocene intrusion of Mount Kinabalu and uplift of the Cordillera is related to collision at the Northwest Borneo Trough. Gold antimony mercury and copper deposits are described and the tectonic setting of oil and gas deposits discussed. * Correlation tables descriptions and ages of all major sedimentary formations of Sarawak Brunei and Sabah * Petrology geochemistry and ages of all volcanic and plutonic formations of North West Borneo and their tectonic significance * Economic geology including the geological setting of offshore oil and gas deposits Cover Geology of North West Borneo Sarawak Brunei and Sabah Acknowledgements Contents Introduction History of Geological Investigation Early exploration Netherlands East Indies geological and mining department The oil company era The Geological Survey (European era 1949 1968) The Geological Survey (Malaysian era 1969 onwards) Regional Tectonic Setting Part A Sarawak Regional Geology Concepts Palaeomagnetism of Sarawak Geomorphology Mesa Topography Karst Topography Rajang Group Inliers in Miri Zone Synclines of Sandy Formations Mud Volcanoes The Kuching Zone Basement Schists Correlatives Terbat Formation Thickness and relationships Lithology Palaeontology and age Correlatives Upper Triassic Formations Serian Volcanic Formation Jagoi Granodiorite Sadong Formation Regional palaeogeography Upper Jurassic and Cretaceous Formations Kedadom Formation Bau Limestone Formation Pedawan Formation Cretaceous Accretionary Complexes Serabang Formation Sejingkat Formation Sebangan Formation Lupar Line complex Upper Cretaceous Tertiary Formations Kayan Sandstone Formation Silantek Formation Plateau Sandstone Cretaceous Plutonism Tertiary High Level Intrusives The Bau district Chemistry Age Origin Sibu Zone Belaga Formation The Layar Member (Stage I Upper Cretaceous) Kapit Member (Stage II Palaeocene to Lower Eocene) Pelagus Member (Stage III Lower to Middle Eocene) Metah Member (Stage IV Middle to Upper Eocene) Kelalan Formation Post Rajang Group Molasse Formations The Tujoh Siman Limestone Sungai Akah (near Long Siniai) Limestones Bekuyat Limestones Bukit Sarang Limestone Nyalau Formation outliers Late Tertiary Volcanism Hose Mountains Batu Laga Linau Balui Plateau Bukit Kajang Plateau Usun Apau Plateau Nieuwenhuis Mountains Related intrusive rocks Chemistry Miri Zone Inliers of Rajang Group (Pre Late Eocene Unconformity) Bawang Member of the Belaga Formation (Stage V) Kelalan Formation Mulu Formation Unconformities Late Eocene Oligocene Mid Miocene Post Upper Eocene Unconformity Molasse The Melinau Limestone Formation The Keramit and Selidong Limestones Kelabit Formation Bukit Mersing Tatau Formation (Upper Eocene Lower Oligocene) [I]* Lower sequence Volcanic sequence Bukit Piring granite granodiorite Post volcanic sequence Palaeontology and age Buan Formation (Upper Oligocene to Lower Miocene) [I II] Shell Palaeofacies Maps Mukah Miri Upper Oligocene 27 Ma (Chattian) (Cycle I)