Meor Hakif Amir Hassan

Geochemical study of volcanic and associated granitic rocks from Endau Rompin, Johor, Peninsular Malaysia.

Geochemical studies and modelling show that both volcanic and granitic magmas from the western part of the Johor National Park, Endau Rompin are different and probably have different sources. The geochemical plot suggests that both dacite/rhyolite and andesite probably have a common origin as in many of the geochemical plots, these two groups form a similar trend. Volcanic rocks have a transitional geochemical character between tholeiite and calc alkaline on a Y versus Zr plot. (La/Yb)N versus La and TiO2 versus Zr modelling show that the crystallization of both granitic and volcanic magmas are controlled by a different set of minerals. The rare earth elements (REE) patterns of some of the granite and volcanic samples have pronounced negative Eu anomaly indicating plagioclase fractionation. The difference between both profiles is that the granite samples show a concave shape profile which is consistent with liquids produced by partial melting of quartz feldspathic rocks containing amphibole among the residual phase. Both magmas were generated at a different time during the subduction of Sibumasu beneath the Indochina blocks.

Sedimentology and stratigraphic architecture of a Miocene retrogradational, tide-dominated delta system: Balingian Province, offshore Sarawak, Malaysia

Abstract The Balingian Province of NW Borneo is a major hydrocarbon-bearing region with production dominantly from Early Miocene (cycle II) coastal to lower coastal plain deposits. A regional sedimentological synthesis is outlined from the main productive interval of three offshore oilfields, which are representative of the depositional environments and stratigraphic architecture in cycle II. Four types of vertical facies successions are recognized: (1) fluvio-tidal channel; (2) tide-dominated delta front; (3) wave-dominated shoreface; and (4) barrier lagoon. The facies successions demonstrate that cycle II consists of a tide-dominated delta system that is partly analogous to the modern Rajang Delta and Lupar Embayment of southern Sarawak. Fluvio-tidal channel and tide-dominated delta successions represent periods of river-fed progradation. Wave-dominated shoreface and barrier lagoon facies successions represent depositional systems that developed during periods of transgression and/or delta lobe abandonment. Cycle II consists of several high-order sequences stacked together into two lower-order, c. 100–300 m thick fining-upwards, unconformity-bounded megasequences. This stratigraphic architecture reflects a combination of hinterland denudation and long-term eustatic sea-level rise. These trends were interrupted by frequent, higher-order relative sea-level falls, which were a result of movement along the West Balingian Line fault zone. Variations in the thickness of megasequences between the three oilfields reflect fluctuations in tectonically driven subsidence rates. This exerted a fundamental control on the reservoir architecture, zonation and correlation and provides a basis for comparing field behaviour.

Permian ultrafelsic A-type granite from Besar Islands group, Johor, peninsular Malaysia

The granitic rocks of the peninsula have traditionally been divided into two provinces, i.e., Western and Eastern provinces, corresponding to S- and I-type granite respectively. The Western Province granite is characterised by megacrystic and coarse-grained biotite, tin-mineralised, continental collision granite, whereas, the Eastern Province granite is bimodal I-type dominated by granodiorite and associated gabbroic of arc type granite. This paper reports the occurrence of an A-type granite from peninsular Malaysia. The rocks occur in the Besar, Tengah, and Hujung islands located in the southeastern part of the peninsula. The granite is highly felsic with SiO2 ranging from 75.70% to 77.90% (differentiation index = 94.2–97.04). It is weakly peraluminous (average ACNK =1.02), has normative hypersthene (0.09–2.19%) and high alkali content (8.32–8.60%). The granites have many A-type characteristics, among them are shallow level of emplacement, high Ga, FeT/MgO and low P, Sr, Ti, CaO and Nb. Calculated zircon saturation temperatures for the Besar magma ranging from 793 ∘ to 806 ∘C is consistent with high temperature partial melting of a felsic infracrustal source which is taken as one of the mechanisms to produce A-type magma. The occurrence of the A-type granite can be related to the extensional back arc basin in the Indo-China terrane during the earliest Permian.

Early Devonian graptolites and tentaculitids in northwest Peninsular Malaysia and a revision of the Devonian–Carboniferous stratigraphy of the region

Meor Hakif Amir Hassan, Erdtmann, B.D., Wang X.-F. & Lee C.P., Early Devonian graptolites and tentaculitids in northwest Peninsular Malaysia and a revision of the Devonian–Carboniferous stratigraphy of the region. Alcheringa 37, 1–16. ISSN 0311-5518. Early Devonian tentaculitids are described from new outcrops in northwestern Peninsular Malaysia. The fossils occur in black carbonaceous shales of the Timah Tasoh Formation exposed in the state of Perlis. The occurrences of the graptolite Monograptus langgunensis and the tentaculitid Nowakia (Turkestanella) acuaria acuaria give an Early Devonian (Pragian or Emsian) age for the black shales. The tentaculitid subspecies Nowakia (Turkestanella) acuaria posterior is reported for the first time from Peninsular Malaysia.

Tidal dynamics and mangrove carbon sequestration during the Oligo–Miocene in the South China Sea

Modern mangroves are among the most carbon-rich biomes on Earth, but their long-term (≥106 years) impact on the global carbon cycle is unknown. The extent, productivity and preservation of mangroves are controlled by the interplay of tectonics, global sea level and sedimentation, including tide, wave and fluvial processes. The impact of these processes on mangrove-bearing successions in the Oligo–Miocene of the South China Sea (SCS) is evaluated herein. Palaeogeographic reconstructions, palaeotidal modelling and facies analysis suggest that elevated tidal range and bed shear stress optimized mangrove development along tide-influenced tropical coastlines. Preservation of mangrove organic carbon (OC) was promoted by high tectonic subsidence and fluvial sediment supply. Lithospheric storage of OC in peripheral SCS basins potentially exceeded 4,000 Gt (equivalent to 2,000 p.p.m. of atmospheric CO2). These results highlight the crucial impact of tectonic and oceanographic processes on mangrove OC sequestration within the global carbon cycle on geological timescales.

Development of Carbonate Buildups and Reservoir Architecture of Miocene Carbonate Platforms, Central Luconia, Offshore Sarawak, Malaysia

Carbonate platforms in the Central Luconia is the most important province in the Sarawak Basin for gas production in the region. These carbonates are economically significant containing 65 trillion cubic feet of gas in place with minor contribution of oil rims. Over 200 carbonate buildups have been seismically mapped, out of which 120 still remain undrilled. These provide potentially attractive exploration targets and incentives to discover the remaining hydrocarbons in the region. The Central Luconia Province is a key geological unit for understanding the distribution of hydrocarbon resources in Malaysia. Although the first hydrocarbon was discovered more than 60 years ago,nevertheless, little effort has been made until now to address the proper facies scheme, cyclicity and reservoir quality of these Tertiary carbonates of Central Luconia. This paper documents the various facies based on the qualitative and quantitative description of cores of five wells cores in three different carbonate platforms with different cyclicity, carbonate buildups and reservoir quality. Detailed petrographic and petrophysical data have been validated to establish the standardized facies scheme. The combination of facies with cyclicity is very important to understand the depositional setting of the sediments and reservoir behavior. Because the sediments which are deposited during the transgressive phase can act as a barrier for hydrocarbon to migrate vertically. Eight facies types have been recognized qualitatively and quantitatively (Table-1), namely F-1 coated grain packstone, F-2 coral (massive) lime pack-grainstone, F-3 oncolite lime grain dominated packstone, F-4 skeletal lime/dolo packstone, F-5 coral (platy) lime mud dominated packstone, F-6 coral (branching) lime dominated pack-grainstone, F-7 cross bedded skeletal lime packstone, and F-8 bioturbated carbonate mud stone (chalk). These eight facies reflect different depositional environments ranging from lagoon to off reef settings. Overall, cores from the five wells consist of 80% of limestone, 15% of dolomitic limestone and 5% of dolomite and argillaceous limestone. The facies consist of eight dominant components comprising, 35%of coral, 30% of red and green algae, 30% of skeletal debris with 5% of other bioclasts. Moldic porosity is dominant (up to 45%), with the remaining are interparticle, intraparticle, vuggy and fracture porosity.

Assessment of heavy metal pollution in surficial sediments from a tropical river-estuary-shelf system: A case study of Kelantan River, Malaysia

To understand the source-to-sink of pollutants in the Kelantan River estuary and the adjacent shelf area in Malaysia, a total of 42 surface sediment samples were collected in the Kelantan River-estuary-shelf system to analyze for grain size, total organic carbon (TOC) content, Al and heavy metals (Cr, Ni, Cu, Zn, Cd and Pb). The surficial sediments were mainly composed of clayey silt and the TOC content in sediments decreased from the river to the shelf. The surficial sediments experienced Pb pollution; Cr only showed a certain level of pollution in the coastal area of the estuary but not in other areas, and Ni, Cu, Zn, and Cd showed no pollution. The heavy metals mainly originated from natural weathering and erosion of rocks and soils in the catchment and enriched near the river mouth. Total organic carbon can promote the enrichment of heavy metals in sediments.

Tectonics and Sedimentation of SW Sarawak Basin, Malaysia, NW Borneo

Structurally SW Sarawak basin is a southward sloping basement characterized by passive margin tectonic that has undergone through varioius tectonic phases viz., Triassic extension, Cretaceous transpression and Oligo-Miocene compression. Rock types and sedimentation of deeper basin zone situated between Schwaner mountains block to the south and SW Sarawak basin to the north suggest progressive marine sedimentation. E-W trending Cretaceous carbonate platform (CCP) occurs in the SW Sarawak basin signify a shelf zone where shallow marine sedimentation progressed during Cretaceous transpression. Oligo-Miocene volcanics from subduction melts intercepted basin profusely forming northwest-southeast trending continental arc zone derived from partial melting of subducting slab underneath SW Sarawak basin. Back-arc extension prevailed during Oligo-Miocene and formed several extensional features. Oligo-Miocene subduction also resulted in closure and exhumation of Sri Aman marginal sea-basin to the east. SW Sarawak basin is further divided in two sub-basins viz., Senibong to the west and Kuching to the east separated by a northeast trending morphotectonic ridge that signify structural element formed due to shearing. Marine sedimentation progressed in these sub-basins mainly during Triassic–Jurassic while tidal and fluviatile sedimentation progressed during early to mid-Tertiary having total thickness of sediments about 9 km. Basin closure and exhumation is marked mainly by the formation of Cretaceous carbonate build-up that has been intruded and dissected by the Oligo-Miocene volcanics. Senibong and Kuching sub-basins are characterized by wide range of transpressive features, while, Sri Aman marginal sea-basin is characterized by oceanic assemblages, ophiolite, serpentinite and pillow basalt.

First record of Homoctenus (Tentaculitoidea, Homoctenida) from the Late Devonian of northwest Peninsular Malaysia

Meor, H.A.H., Yong, A.M., Zakaria, M.Z.Z. & Ghani, A.A., 2.6.2015. First record of Homoctenus (Tentaculitoidea, Homoctenida) from the Late Devonian of northwest Peninsular Malaysia. Alcheringa 39, 550–558. ISSN 0311-5518. The homoctenid tentaculitoid genus Homoctenus is reported for the first time from Peninsular Malaysia. The fossils derive from the Upper Devonian Sanai Limestone, exposed in the state of Perlis, northwest Peninsular Malaysia. The fossils are closely related to Homoctenus tenuicinctus tenuicinctus and are described as Homoctenus sp. cf. H. tenuicinctus. The homoctenids were recovered from an interval containing a rich conodont assemblage, indicating a Frasnian age (Palmatolepis linguiformis Zone). Meor Hakif Amir Hassan [meorhakif@um.edu.my], Yong Adilah Mustafa [yongadilah@gmail.com], Mohamad Z.Z. Zakaria [zulhafiszariq@siswa.um.edu.my], Azman A. Ghani [azmangeo@um.edu.my], Geology Department, University of Malaya, 50603 Kuala Lumpur, Malaysia. Received 12.4.2015; revised 27.5.2015; accepted 2.6.2015.