Central Belt Of Peninsular Malaysia Research Articles

Trace Element Analysis of Pyrite and Arsenopyrite Using the LA-ICPMS Technique in Pulai, Central Belt of Peninsular Malaysia

The Pulai gold deposit is one of the most promising gold prospects in the Central Belt of Peninsular Malaysia. It is found within the Permian-Triassic Gua Musang sequence of metasediments and metavolcanics and in a structurally controlled NE-SW major fault. Various ore minerals, including pyrite, arsenopyrite, chalcopyrite, sphalerite, pyrrhotite, and galena are typically associated with this deposit. Four types of pyrite (Pyrite 1, Pyrite 2, Pyrite 3, and Pyrite 4) and two types of arsenopyrite (Arsenopyrite 1 and Arsenopyrite 2) were characterised based on their morphological and textural differences. In this region, gold occurs as refractory gold in the nanoparticle form and in the state of Au+ within the structure of sulphides of variable concentrations. Through the detailed laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) trace element mapping analysis of pyrite and arsenopyrite, the main Au-bearing sulphides were found within vein-hosted Pyrite 4 and Arsenopyrite 2 during late phase mineralisation, while Pyrite 3 had the lowest Au concentration. Two phases of Au enrichment were recorded in Pyrite 4, mainly in the core (2 to 11.7 ppm; average 1.4 ppm) and margin of the grain (0.3 to 8.8 ppm; average 1.2 ppm), whereas the highest Au content was detected in the core of Arsenopyrite 2 (0.3 to 137.1 ppm; mean 31.9 ppm). The enrichment of Au is associated with As, forming a zoning elemental pattern distribution. Other trace elements, including Co, Ni, Sb, Pb, Bi, Cu, and Zn, show systematic variation in their composition between the various types of pyrite and arsenopyrite. For early-phase sulphides, the Au enrichment localised at the margin of Pyrite 2 and Arsenopyrite 1, together with Co–Ni, Pb–Bi–Sb, and Ag in the same oriented pattern, suggesting the remobilisation and redistribution of Au in sulfides. Meanwhile, the late crystallisation phase of vein-hosted sulphides formed a rich Au–As ore zoning pattern in the core of Arsenopyrite 2 and Pyrite 4. The second phase of Au enrichment continued at the margin of Pyrite 4 through the remobilisation and precipitation of Au together with Ni, Co, Sb, Pb, Bi, Ag, and Cu. Subsequent deformation then reactivated the late fluid system with the enrichment of Sr, Ba, Rb, Ag, and Zn along the fractures and outermost rim of Pyrite 4 and Rb–Sr–Ba–Pb–Bi along the rim of Arsenopyrite 2. The Pulai gold prospect is interpreted as an orogenic-style gold mineralisation where arsenic can be used as an indicator for proximity to ore mineralisation in exploration.

Trace Element Composition of Pyrite from Selected Black Shale and Chert Exposures in the Central Belt of Peninsular Malaysia: Implications for Mineral Exploration

Sedimentary and hydrothermal pyrites contained in selected Malaysian black shale and cherts have been analysed using laser ablation inductively coupled plasma (LA ICP-MS) and electron probe microanalysis (EPMA) at the University of Tasmania, Australia. This study shows that gold is concentrated in sedimentary and hydrothermal pyrite in the Middle Permian to Late Triassic black shales and Devonian cherts. According to LA ICP-MS analysis, gold contents in pyrite varied from 0.5 to 0.8 ppm Au in the Permo-Triassic black shale and between 0.2 and 0.8 ppm Au in the Devonian cherts. The lowest level of gold (0.3 ppm Au) was observed in the Permo-Triassic black shale that crops out at the Selinsing gold mine. In the Permo-Triassic period, the selenium contents display one peak (average range: 63.4–103.4 ppm Se) that is far from any gold deposit and one lowest point (average: 5.3 ppm Se) at the Selinsing gold deposit. In the Devonian period, the selenium content in sedimentary pyrite shows a peak (72.6–243.8 ppm Se) in the cherts. EPMA and LA ICP-MS data show consistent Se content variation in the Devonian and Permo-Triassic periods. Using selenium as a proxy for atmospheric oxygenation, the lowest level of Se content in the Permo-Triassic period is believed to decrease atmospheric oxygenation, as recorded in sedimentary pyrite found in black shale from the Selinsing gold deposit. The two peaks of selenium contents are interpreted as periods of increased atmospheric oxygenation. From an exploration perspective, the concentration of gold in sedimentary pyrites makes them sources for gold in the central sedimentary basin of Peninsular Malaysia. Therefore, the two maximum levels of Se and gold content during Permo-Triassic and Devonian times correspond to two stratigraphic levels of potential for orogenic gold mineralisation in the district. The EPMA data show significant values of Co over Ni in pyrite from the Gua Musang, Semantan, and Karak formation black shales, indicating a volcanic contribution of Co during the formation of sedimentary pyrite. Based on the current study’s findings, gold exploration should not be restricted to areas in and around the Selinsing gold mine, Buffalo Reef, Penjom mine, Tersang mine, and Bukit Koman mine but can be extended to BRSZ Units 1 and 2, Gua Musang, and Karak formations in the central belt of Peninsular Malaysia.

U-Pb Dating, Lead Isotopes, and Trace Element Composition of Pyrite Hosted in Black Shale and Magmatic Rocks, Malaysia: Implications for Orogenic Gold Mineralization and Exploration

Several orogenic/sediment-hosted gold deposits are widely distributed in the Central Belt of Peninsular Malaysia. This study combines U-Pb dating with the isotope composition of lead as well as gold content in ore and magmatic rock-hosted pyrite. It aims to investigate the age of gold mineralization and possibly establish a link between gold mineralization and magmatic intrusion in the district. The results show that the S-type magmatic rocks yield crystallisation ages ranging from 204.1 ± 4.7 Ma to 223 ± 3.2 Ma with low magnetic susceptibility measurements below 3 × 10−3 SI unit. These ages fit within the 200–250 Ma Pb-Pb model age of the Pb isotopic composition of K-feldspars. Pyrite trace element mapping has shown that gold and lead show zoning patterns occurring at the same time in pyrite. The Pb isotope composition of the cores of pyrite grains indicate that the approximate model age of gold mineralization is 200 Ma. This age is close to 197–199 Ma (Early Jurassic), previously determined by K-Ar dating of sericite which was interpreted to be the age of gold mineralization. In this study, gold content varies up to 793 ppb in the analysed magmatic rock-hosted pyrites, indicative of a likely magmatic contribution to gold mineralization.

Mineralogy and Geochemistry of Gold Mineralization at Southern part of Ulu Sokor Gold Deposit, Kelantan, Malaysia

The Ulu Sokor gold deposit is classified as orogenic type deposit with evidence from previous studies on the structural, mineralogical, alteration, fluid inclusion, and stable isotope data. This study focuses on the mineralogy and geochemical analysis of representative ore rock samples from southern part of Ulu Sokor gold deposits. The project area is situated at the North of Kelantan state which lies on the Central Belt of Peninsular Malaysia. The main objective of this research is to determine the gold mineralization enrichment pattern relative to other trace elements based on the new data of mineralogy and geochemical analysis. Gold mineralization is primarily hosted in structurally controlled quartz vein which occurs in various degrees of ductile-brittle environment. Based on the field relationships, ore microscopy and geochemical data analysis, there are two main gold mineralization type in the southern part of Ulu Sokor gold deposit, namely (1) Gold associated and as inclusions in bismuthinite based on the mineralogy study, and (2) Refractory gold occurs as lattice bound in pyrite based on the Au/As molar ratio. In terms of mineral exploration and gold prospecting, the significant enrichment in this study area is Bi. However, some other metals can also be considered as a significant value in this area such as Pb, As, Cu and Zn. From the bulk ore chemistry, the geometric mean values of Au and Bi are 1.9 ppm Au (n=23) and 96 ppm Bi (n=22), respectively. The knowledge base for bismuth minerals in Malaysia would provide a significant targeting clue for the gold mineralization.

Texture and morphology of veins and their relationship to gold mineralization in the Penjom deposit, Malaysia

AbstractPenjom deposit is an orogenic gold deposit located in the Central Belt of Peninsular Malaysia. Gold mineralization is associated with various styles and textures of quartz‐carbonate veins hosted within the metasedimentary as the main host rock and felsic igneous rock including minor volcanic rock. Vein textural features and morphologies have been investigated based on macroscopic and microscopic characteristics to understand the process of veins formation, and the relationship with gold mineralization. At the hand specimen scale, veins show a variety of textures that are either primary or superimposed. Primary textures are comb, massive anhedral buck quartz veins, and laminae veins or vein septa representing early vein introduction without vein modification. Extension veins that are normally concordant to maximum compressive stress direction show either a common comb texture within these veins or buck texture inside thick veins. Secondary textures are ribbon, stylolites, breccias, and late spider veinlets that overprint early veins formed during repeated structural episodes. Later stage deformation events superimposed on the existing veins texture results in intensely deformed veins. The interrelationship of structure, vein‐type and texture, gold and sulfide mineralogy have been correlated to constrain the episodes of gold mineralization in the Penjom deposit. Characteristics of vein textures indicate physio‐environment under confining lithostatic pressure where fluids filled the space through crack and sealing mechanism. Vein systems and gold mineralization events that have been correlated with the D2D3 (fold‐fault) deformation events and inferred to be temporally related to the late‐stage regional orogenic event dated Late Triassic‐Early Jurassic that affected Peninsular Malaysia.

Geochemistry of Sphalerite from the Permian Volcanic-Hosted Massive Sulphide (VHMS) Deposits in the Tasik Chini Area, Peninsular Malaysia: Constraints for Ore Genesis

The Bukit Botol and Bukit Ketaya deposits are two examples of volcanic-hosted massive sulphide (VHMS) deposits that occur in the Tasik Chini area, Central Belt of Peninsular Malaysia. The mineralisation is divided into subzones distinguished by spatial, mineralogical, and textural characteristics. The primary sulphide minerals include pyrite, chalcopyrite, sphalerite, and galena, with lesser amounts of Sn- and Ag-bearing minerals, with Au. However, pyrrhotite is absent from both deposits. This study presents the results of sphalerite chemistry analysed by using an electron microprobe. Two types of sphalerite are recognised: sphalerite from the Bukit Botol deposit reveals a range of <DL to 24.0 mole% FeS, whereas sphalerite from the Bukit Ketaya deposit shows a range of <DL to 3 mole% FeS. Significant variations are shown in Zn, Cu, Cd, and Ag levels. Although the sphalerite has a wide variation in composition, a discernible decreasing Fe trend is exhibited from the stringer zone towards massive sulphide. This compositional variation in sphalerites may in part reflect variable temperature and activity of sulphur in the hydrothermal fluids during ore formation. Alternatively, the bimodal composition variations suggest that mineral chemistry relates to contrasting depositional processes. The Zn/Cd ratios for sphalerite from both these deposits are similar to those exhibited by volcano−sedimentary deposits with a volcanic origin. Therefore, the consistently low Cd concentrations and moderate to high Zn/Cd ratios suggest mixing of seawater and minor magmatic fluids controlling the chemistry of sphalerite at both deposits during their formation.

Genesis of the Selinsing gold deposit, Peninsular Malaysia: Constraints from mineralogy, geochemistry and in situ sulfur isotope compositions of sulfides

As a renowned orogenic lode gold deposit, the Selinsing gold deposit is located in the Central Belt of Peninsular Malaysia. Geologically, the gold deposit is characterized by auriferous quartz veins and fine-grained gold minerals coexisted with sulfides, and the ore body is hosted by low-grade metamorphic sedimentary rocks and volcanic rocks. Furthermore, gold mineralization is closely related to tectonic deformation. Four main stages of vein formation have been identified, namely, (1) quartz-pyrite-arsenopyrite vein, (2) quartz-pyrite-gold vein, (3) quartz-stibnite-pyrite vein, and (4) quartz-chlorite vein. The occurrence of gold includes two types, i.e., visible gold and invisible gold. The former is featured by coarse-grained gold (millimeter-scale, such as auriferous quartz veins) and fine-grained gold (micron-scale, such as native gold, calaverite, and electrum), the latter is contained in pyrite and arsenopyrite in the form of nano-scale native gold particles (Au0) and lattice gold (Au1+). The geothermometer of arsenopyrite and chlorite as well as temperature-sulfur fugacity diagram indicate that the temperature and sulfur fugacity of hydrothermal fluid decrease gradually. Considering that the sulfur fugacity drops gradually and aqueous inclusions coexist with carbonic inclusions, it is inferred that sulfuration reaction in which sulfur is consumed to produce sulfides and fluid immiscibility or phase separation may be responsible for gold precipitation. Tested by LA-MC-ICP-MS, the in-situ sulfur isotope compositions of sulfides formed in different stages are homogenous (about −1 to 1‰) and the calculated H2S-dominated hydrothermal fluid is also consistent (about −2 to 0‰) in sulfur isotope compositions, which reflect the mantle or ultrabasic rock and basic rock or magmatic rocks may be a potential source of sulfur. Combined with possible source and tectonic evolution of Peninsular Malaysia, possible metallogenic processes are proposed to explain genesis of the Selinsing gold deposit and other gold deposits in the Central Belt, i.e., ore-forming fluid was differentiated from oceanic crust and/or fertilized mantle wedge, or ore-forming fluid may be sourced from concealed magmatic rocks that formed by subduction of the Palaeo-Tethys toward the East Malaysia block.

Microthermometric evidence for the formation of Permian VHMS deposits in Tasik Chini area, Central Belt of Peninsular Malaysia

The VHMS deposits of Tasik Chini area are located in the Pahang State of Central Belt, Peninsular Malaysia. The deposits occur in a package of Permian volcanics within mixed volcano-sedimentary sequence, and have been exploited from the Bukit Botol and Bukit Ketaya deposits. They have many similarities with Kuroko-style massive sulfide deposits. The host rocks at both deposits are felsic volcanic rocks of rhyolitic to rhyodacitic composition. Mineralization occurs as distinct ore zonation forming a stringer to massive sulfide zone at the footwall followed by barite lenses and exhalite layers (Fe + Mn ± Si ore) at the stratigraphic top. The sulfide phases are characterized by pyrite as the major sulfide mineral, with subordinate chalcopyrite, sphalerite and rare galena; traces of gold, silver- and Sn-bearing minerals occur in the massive sulfide and barite ores. Primary fluid inclusions within quartz and barite occur as two types: (1) type I: two phase, liquid-vapour inclusions without daughter minerals, and (2) type II: three phase, liquid CO2-bearing carbonic inclusions. These three phase inclusions include liquid H2O, liquid CO2 and vapour CO2, with variable CO2 content, and often decrepitate before complete homogenization. Microthermometric measurements of the type I inclusions show that the temperature of homogenization (Th) varies between 180 °C and 310 °C with salinities ranging from 1.0 to 15.0 wt% NaCl equivalent in the quartz samples. Homogenization temperatures (Th) of 190 °C to 300 °C and salinities between 1.0 and 13.0 wt% NaCl equivalent are recorded from the barite samples. Type II inclusions have an initial melting temperature range of −57.1 °C to −57.5 °C, clathrate melting temperature (Tmclathrate) of 7.4 °C to 8.0 °C and CO2 homogenization temperature (ThCO2) between 30.1 °C and 30.3 °C, and salinity ranging from 4.0 to 5.1 wt% NaCl equivalent. Densities, pressure and depth of ore forming fluids range from 0.711 to 0.970 g/cm3, 12 to 93 bars, and ∼1500 m depth of seawater. Laser Raman spectroscopic analysis shows the presence of CO2 in the carbonic inclusions. The fluid inclusion results suggest that the main ore fluid during the formation of the Tasik Chini VHMS deposit is a seawater-dominated fluid, but contribution from a modified seawater or possibly magmatic origin is also indicated by higher salinities relative to seawater (3.2 wt% NaCl) and the presence of CO2. Taking into account the regional geodynamic evolution, it is also concluded that the formation of VHMS deposits in the Tasik Chini area occurred in a back-arc geotectonic setting.

Textures and trace element composition of pyrite from the Bukit Botol volcanic-hosted massive sulphide deposit, Peninsular Malaysia

The Bukit Botol volcanic-hosted massive sulphide (VHMS) deposit is located in the Central Belt of Peninsular Malaysia. The deposit occurs in a package of Permian-aged coherent felsic volcanic and volcaniclastic rocks which have a geochemical signature indicative of a volcanic arc tectonic setting. Mineralisation shows distinct ore zonation, forming a stringer to massive sulphide zone at the footwall followed by barite lenses and exhalite layers (Fe-Mn ore) at the top. Mineralogy is characterised by pyrite as the major sulphide mineral, with minor chalcopyrite, sphalerite, and rare galena; traces of gold, silver- and tin-bearing minerals also occur in the massive sulphide and barite ores. Laser ablation inductively coupled plasma mass spectrometry (LA−ICP−MS) analysis combined with the textural characteristics of pyrite provides evidence for significant variations of trace elements in different pyrite types at Bukit Botol, having three types of pyrite in the paragenetic sequence. The concentrations of As, Se, Te, Cu, Zn and Pb decrease from the early pyrite 1 to the late stage pyrite 3, and the Co/Ni ratios vary for the three pyrite types. The combined textural and compositional data of pyrite suggest that the hydrothermal fluid responsible for mineralisation evolved from an early, high temperature, reduced, low pH and desulphurized fluid to more S-rich, oxidized, high pH and cooler fluid. Available sulphur isotope data from the Bukit Botol deposit point to reduced seawater, along with a possible magmatic contribution, as the most probable sources for the ore-forming fluids.

Pb‐isotope compositions of the Tasik Chini volcanic‐hosted massive sulfide deposit, Central Belt of Peninsular Malaysia: Implication for source region and tectonic setting

AbstractLead isotope data of sulfides and host volcanic rocks from the Bukit Botol and Bukit Ketaya deposits, the two representative deposits of the Tasik Chini volcanic‐hosted massive sulfide (VHMS) deposit, Central Belt of Peninsular Malaysia, are reported. Lead isotope compositions of the associated sulfide minerals and volcanic rocks from the Bukit Botol deposit exhibit homogeneous and less radiogenic values (206Pb/204Pb showing a range of composition from 18.14 to 18.20, 207Pb/204Pb between 15.52 and 15.59 and 208Pb/204Pb from 37.96 to 38.35). Similarly, the Pb isotopic compositions of the host volcanic rocks from the Bukit Ketaya deposit yielded a narrow range to those of the sulfide samples (206Pb/204Pb from 18.04 to 18.20, 207Pb/204Pb between 15.43 and 15.57 and 208Pb/204Pb of 37.96 to 38.30). The uniform Pb‐isotope compositions of the sulfides in the ore horizon and the host volcanic rocks from both deposits suggest a derivation from a similar source reservoir and mineralization processes. In the framework of the tectonic model for the Central Belt of Peninsular Malaysia, both deposits display a range of lead isotopic compositions originated from mixing of bulk crust/juvenile arc and minor mantle sources, which are typical for VHMS deposits in an island arc–back arc setting.

Sulfur isotope characteristics of the Permian VHMS deposits in Tasik Chini district, Central Belt of Peninsular Malaysia

Sulfur isotope data from sulfide and sulfate minerals have been measured from the two typical examples of the Permian volcanic-hosted massive sulfide (VHMS) deposits at the Tasik Chini district in the Central Belt of Peninsular Malaysia. In this study, we present the sulfur isotope data for 33 sulfide minerals and 23 barite samples from two VHMS deposits in the Tasik Chini district. Sulfides show a narrow range of sulfur values from -2.9%o to +8.30%o, which can be interpreted to be derived from a mixed sulfur source of reduced seawater sulfate with the possible addition of magmatic sulfur. Sulfate sulfur in barites yields a δ34S range between 11%o and 22%o, which is comparable to that of Permian seawater sulfate. Sulfur isotope results obtained for the VHMS deposits in the Tasik Chini district suggest that the source of ore fluids during the formation of the Tasik Chini VHMS deposit is a seawater-dominated fluid with probably minor magmatic fluid input. This is similar to VHMS associated with ancient and modern submarine hydrothermal systems.

Geochemistry, geochronology, and tectonic setting of early Permian (~290 Ma) volcanic-hosted massive sulphide deposits of the Tasik Chini district, Peninsular Malaysia

ABSTRACTThe age and nature of Permian volcanism and sulphide mineralization in Malaysia are poorly understood. The Tasik Chini district is located in the Central Belt of Peninsular Malaysia and hosts the Bukit Botol and Bukit Ketaya volcanic-hosted massive sulphide (VHMS) deposits. These deposits are hosted by felsic-dominated Permian felsic volcanics that are part of a mixed volcano-sedimentary rock succession. Four mineralization zones were identified in both deposits: (1) stringer sulphide/zone; (2) massive sulphide zone; (3) barite zone; and (4) Fe-Mn and Fe-Si zones. The stringer and massive sulphides generally define the lower mineralized zones, whereas the barite, Fe-Mn, and Fe-Si layers define the stratigraphically upper mineralized zones. The main sulphide phases are pyrite, chalcopyrite, sphalerite, rare galena, and trace Sn-, Au-, and Ag-bearing minerals, with the latter two confined to the massive sulphide and barite zones. Trace and rare earth element data for the host rhyodacite-rhyolite at both deposits are consistent with formation in a volcanic arc palaeotectonic setting. In comparison, the trace element data for Triassic volcanic and intrusive rocks from the Tasik Chini area have moderate to low high field strength element (HFSE) concentrations along with transitional (Zr/Y = 4–7) to tholeiitic (Zr/Y = 2–4) affinities, but have similar magmatic arc signatures. Laser ablation inductively coupled mass spectrometry (LA-ICP-MS) U–Pb zircon dating of rhyolites from the Bukit Botol deposit yields early Permian (286 ± 4 to 292 ± 3 Ma) ages. Similarly, the zircon U–Pb age results for Bukit Ketaya rhyolites reveal early Permian (286 ± 2 to 288 ± 4 Ma) ages. The differences in geochemical and geochronological results between the early Permian host and the later Triassic volcanic and intrusive rocks are likely due to tectonic progression from a volcanic arc environment to a collisional setting.

INTEGRATION OF PALSAR AND ASTER SATELLITE DATA FOR GEOLOGICAL MAPPING IN TROPICS

Abstract. This research investigates the integration of the Phased Array type L-band Synthetic Aperture Radar (PALSAR) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data for geological mapping applications in tropical environments. The eastern part of the central belt of peninsular Malaysia has been investigated to identify structural features and mineral mapping using PALSAR and ASTER data. Adaptive local sigma and directional filters were applied to PALSAR data for detecting geological structure elements in the study area. The vegetation, mineralogic and lithologic indices for ASTER bands were tested in tropical climate. Lineaments (fault and fractures) and curvilinear (anticline or syncline) were detected using PALSAR fused image of directional filters (N-S, NE-SW, and NW-SE).Vegetation index image map show vegetation cover by fusing ASTER VNIR bands. High concentration of clay minerals zone was detected using fused image map derived from ASTER SWIR bands. Fusion of ASTER TIR bands produced image map of the lithological units. Results indicate that data integration and data fusion from PALSAR and ASTER sources enhanced information extraction for geological mapping in tropical environments.

Structural analysis and vein episode of the Penjom Gold Deposit, Malaysia: Implications for gold mineralisation and tectonic history in the Central Belt of Malaysia

Gold mineralisation at the Penjom Gold Deposit, in the Central Belt of Peninsular Malaysia is dominantly hosted in structurally controlled quartz-carbonate veins that display a variable degree of overprinting events under a ductile–brittle regime. Mineralised veins are categorised into two main episodes: fold and thrust-related veins mainly comprised of bedding and Penjom Thrust parallel shear veins and associated extension veins developed during a D2 event. In addition, NE to NNE trending splays and Penjom-Thrust-parallel reverse–dextral and locally NNW to NS reverse-sinistral faults overprint earlier vein events forming a new episode of extensional veins during D3 event, mostly at the fault contacts of intrusives either as shallow-dipping or vertical sheeted, stockwork or brecciated veins. At least two episodes of faulting D4–D5 are evident which postdates the main episodes of veining and mineralisation. This is indicated by a series of late episodes NS trending sinistral and oblique to normal faults which transect and displace the Penjom Thrust and the folded footwall sequence at low angles and responsible for intensive vein deformation along the Penjom Thrust and displacement of ore body. Structural interpretations of mineralised veins suggest that the veins were formed under a compressional to transpressional regime with later post-vein displacement in a transtensional to extensional regime. Vein formation in response to deformation observed at Penjom reflects regional structural deformation within the Central Belt of Peninsular Malaysia and specifically along the Bentong–Raub Suture zone.

Integrating PALSAR and ASTER data for mineral deposits exploration in tropical environments: a case study from Central Belt, Peninsular Malaysia

Remote sensing investigation for mineral deposits exploration in tropical environments is not completely implemented due to obstacles imposed by tropical climate. Recent challenge is to use the most suitable recent generation of remote sensing data and image processing approaches for the detection of lithological units and structural features associated with epithermal and polymetallic vein-type mineralisation, which are concealed by tropical rainforest. This research investigates the integration of the Phased Array type L-band Synthetic Aperture Radar (PALSAR) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data for geological mapping applications in tropical environments. The eastern part of the Central Belt of Peninsular Malaysia with high potential for gold prospecting has been investigated as a case study to identify structural features and mineral assemblages using PALSAR and ASTER data. Adaptive local sigma and directional filters were applied to PALSAR data for detecting geological structure elements in the study area. Vegetation, mineralogic and lithologic indices for ASTER bands were tested in tropical climate. Lineaments (fault and fractures) and curvilinear (anticline or syncline) were detected using PALSAR image map of directional filters (N–S, NE–SW and NW–SE).Vegetation index image map show vegetation cover using ASTER visible and near-infrared radiation (VNIR) bands. High concentration of clay minerals zone was detected using image map derived from ASTER shortwave infrared (SWIR) bands. ASTER thermal infrared (TIR) bands produced image map of the lithological units. Results indicate that data integration from PALSAR and ASTER sources enhanced information extraction for geological mapping in tropical environments. The study presented here encourages further applications of satellite remote sensing data integration for mapping structural elements, hydrothermal alteration minerals and lithological units associated with epithermal and polymetallic vein-type mineralisation in tropical environments.

Field Evidence of Magma Mixing in Plutonic Rock from the Benom Complex, Central Belt of Peninsular Malaysia

The a lka lic seri es of the Benom Complex, Pahang, consists of monzonite, syenite and gabbro ic rock. The contact between monzonite and gabbroic rock suggest that both magmas are mixed. Ev idence of the mix ing can be seen at the new roadcut outcrop a long the Benta township by-pass such as dispersion of K-fe ldspar from monzonite in the gabbroic rock. The end stage of this dispersion is the free sw imming of K-fe ldspar individual crystals in the gabbroic material. Thi s structure is interp reted as the result of mechanical transfer during the mafic-fe lsic magma interaction and mix ing event. All these fea tu res suggest an origin for the alka lic in termediate rocks of the Benom Complex invo lvi ng a magma mix ing process ..

Geochemistry and petrology of syenite, monzonite and gabbro from the Central Belt of Peninsular Malaysia

The Benom Igneous Complex is situated in the central part of of this belt forms a pear shaped batholith consists of a variety of igneous rocks ranging in composition from granitic to syenitic to monzonitic and gabbroic. The syenitic, monzonitic, gabbroic are found mainly in the western part of the batholith. The range of SiO 2 for each of the gabbro, syenite and monzonite are 46.5 to 49.1%, 52.9 to 56.9% and 56.6 to 64.7% respectively and characterized by high alkali content, shoshonitic with I type characteristics. They have very high LIL elements, i.e. Ba and Sr are nearly 1000 times rock/mantle. The high Ba and Sr values may results from the penetration of the lower lithosphere by a small volume of mantle material that is enriched in those elements.

Guadalupian (Middle Permian) brachiopods from Sungai Toh, a Leptodus Shale locality in the Central Belt of Peninsular Malaysia Part I: Lower Horizons

This work presents a systematic study of Permian Brachiopoda from the Sungai Toh Leptodus Shale locality, Pahang State, Peninsular Malaysia. This locality lies within the Central Belt of Peninsular Malaysia, a tectonic unit characterised.by tuffaceous sediments and limestones of Late Palaeozoic age. Two brachiopod-bearing horizons were studied in detail at this locality, the lower one (Horizon 2) bearing a mixed plant and invertebrate assemblage, including the brachiopods Urushtenoidea chaoi (CHING), Leptodus richthofeni KAYSER, Anidanthus cf. sinosus HUANG, Acosarina dorashamensis (SOKOLSKAJA), A. minuta (ABleH) and unidentifiable species of Linoproduetus, Neochonetes, and Strophalosiina. Horizon 3 contains a more abundant and diverse brachiopod fauna, comprising a total. of 57 species representing 47 genera, including Vediproductus punetatiformis (CHAO), Permianella typica HE & ZHU, Tranrennatia gratiosa (WAAGEN), Leptodus richthofeni KAYSER, Leptodus cf. tenuis (WAAGEN) and Semibrachythyrina [= Alphaneospirifer] cf. pyramidiformis LIANG. It is suggested in this study that the age of the Sungai Toh locality is Capitanian (late Guadalupian) to possibly Wuchiapingian (early Lopingian), as it appears to correlate well with the Lengwu fauna from Zhejiang in eastern China. The palaeobiogeographical affinities of the Sungai Toh fauna are interesting, mainly indicating strong Palaeo-equatorial affinities, while there are also some elements more typical of the cooler periGondwana Region.

'Mantle plume' type magmatism in the Central Belt of Peninsular Malaysia and its tectonic implications

None of the existing tectonic models of Peninsular Malaysia fully explains the spatial, age or geochemical characteristics of the Central Belt intermediate to basic igneous rocks. The Central Belt granitoids, which lie critically close to the Bentong-Raub Line, have distinct geochemical characteristics. They have very high LIL elements, i.e. Ba and Sr are nearly 1,000 times rock/mantle. The high Ba and Sr values may result from the penetration of the lower lithosphere by a small volume of mantle material that is enriched in those elements attributed to 'mantle plume' type magmatism. Other supporting evidences include the presence of bimodal magmatism, the presence of mafic enclaves of older granitoids in younger granitoids and the new age data indicated that there is a significant time interval (up to between 30 Ma) between the first mafic magmatism and the later felsic magmatism; the Central Belt plutons are post­ orogenic and penecontemporaneus with rapid post-orogenic uplift, and erosion with the development of the Jurassic­ Cretaceous continental deposits of the Central Basin; the presence of thin continental crust beneath the Central Belt; the Benom granite has yielded an initial 87Srj86Sr ratio of 0.7079, which points to an origin in highly enriched lithospheric mantle; and the presence of mafic enclaves is consistent with a mafic lower crust beneath central belt formed by underplating. A model have been proposed that involved the oblique convergence of the two tectonic provinces of Peninsular Malaysia where slab breakoff which is the natural consequence of the attempted subduction of the continental crust is invoked to account for the 'mantle-plume' type magmatism of the Central Belt. The outcome of the slab breakoff is the long linear belt of single plutons characterized by high-K, shoshonitic granitoids with characteristic trace element signatures, specifically high Ba and Sr, which lie critically close to the Bentong-Raub Line. Other features include the bimodal association of mafic and felsic rocks, the low grade regional metamorphism, thinned continental crust, rapid uplift and erosion with the development of extensionaVtranstensional basins.

High Ba igneous rocks from the Central Belt of Peninsular Malaysia and its implication

Trace element characteristics of gabbro-monzonite-syenite from the Benom Igneous Complex, Sungai Ruan, Raub show that they are very high in large ion lithophile (LIL) elements. The rocks contain: Ba (2,401-10,744 ppm; mean: 4,590 ppm), Rb (257-434 ppm) and Sr (578-2,340 ppm; mean: 1,000 ppm) which is higher compared to the rocks from other areas. The strong enrichment of these elements (Ba and Sr) is probably related to transfer of enriched (hydrous?) fluids from the mantle into the lower crust and possibly initiated melting to form the rocks besides the possibility of being linked to mantle plumes.