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This section summarizes the research questions and identifies knowledge gaps in relation to the research work. This study attempts to resolve a long-standing debate as to whether the sedimentary rocks or the granitoids in the Sibumasu and East Malaya Terranes are the likely source of gold for sediment-hosted orogenic gold deposits such as the Selinsing gold deposit, the Penjom gold deposit, the Tersang gold deposit, and the Bukit-Koman gold deposit in Central Malaysia. A sedimentary source of gold relates to Au enrichment in diagenetic pyrites coupled with sedimentary sulphur signature from stable isotope determination. Gold content in diagenetic pyrites should vary positively with Mn, Ag, V, Mo, and Ni contents. By contrast, a granite source commonly shows a magmatic sulphur isotope composition. And the Pb isotopic age of K- feldspar in granite should approximate the age of gold mineralisation at a given gold deposit in the district. Previous research works completed at the Selinsing, Tersang, Bukit-Koman and Penjom gold deposits concentrated on U-Pb zircon dating, mineral paragenesis, and fluid inclusion studies (Ng, 1986; Yeap, 1993; Kamar et al., 1994; Wan Fuad and Purwanto, 2002; Makoundi, 2012). However, there is little published research on the sedimentary host rocks, in particular their lithogeochemistry, chemical environment of deposition and potential to be the source of gold in the ore deposits.

Previous researchers had considered that gold mineralisation in the Central Belt is related to a granitic source (Scrivenor, 1928; Willbourn and Ingham, 1933; Richardson, 1939). Unfortunately, there is little evidence in relation to the timing, and geochemical fingerprinting of gold mineralisation in Central Malaysia. In addition, Yeap (1993, p.343) asserted that gold was probably sourced from the lower crust or mantle, based on the Pb isotope character of the Maran ore in Central Malaysia. Nevertheless, there is a lack of convincing arguments to support the type of granitoid (magnetite or ilmenite-series), which relates to the source of gold in the district.

4 Goh et al. (2005) claimed that the main factors that controlled the input of gold were sedimentary and metasedimentary rocks, heating and depositional structures; however, little evidence was given on the source rock characteristics that controlled the emplacement and formation of gold mineralisation in the district. Again, Goh et al. (2005) reported that the granitoids generated heat that induced hydrothermal fluids to circulate through the volcanic- sedimentary rocks. Generally, recent geochemical studies have shown that some black shales contain anomalous levels of gold and arsenic (Pitcairn et al., 2006; Large et al., 2010). It has been suggested that syngenetic gold in black shales within sedimentary basins is sourced by erosion of the hinterland, attached to detrital clay particles and transported as colloidal gold by high-volume river systems (Thomas et al., 2011; Bull and Large, 2014). These authors strongly argue that carbonaceous rocks are good gold source rocks in sedimentary sequences (Pitcairn et al., 2006; Tomkins, 2010; Large et al., 2011).

The majority of gold in the shales occurs in sedimentary pyrite (Pitcairn et al., 2006; Large et al. 2009) and is regarded as an early sedimentary stage of the pre-concentrated gold to form source rocks favourable for later orogenic gold formation (Large et al., 2010). A related question that is being addressed in this study is “did detrital clays and/or organic matter play a role as a metal carrier to sedimentary basins in Malaysia? If that is so, then it provides a link between the shales and ore deposits and has huge implications for the genesis of gold in the sediment-hosted, orogenic gold deposits which are found in the Central Gold Belt of Peninsular Malaysia. In previous research work, organic carbon concentrated gold into sediments. For instance, good correlation was found between total organic carbon and gold content from three carbonaceous gold-bearing formations of South China implying the role of organic carbon in concentrating gold into sediment (Hu Kai, 2000). Clay minerals are produced from the breakdown of pre-existing rocks and are transported together with trace metals and deposited in black shales. Trace elements (Zn, Pb, Cu, Mo, Se, V, U, Ni, As, Ag, Cr, and Au) are adsorbed

5 onto clays and deposited into basin during formation of black shales. In this thesis, the roles of clays and organic matter in transporting gold into sedimentary basins and deposition in black shales are investigated. Ore genesis studies at the Selinsing gold deposit in Malaysia (Makoundi, 2012; Makoundi et al., 2014) have yielded little data on whether granite-related fluids or sedimentary fluids contributed to the deposition of gold in the area.

Recent investigations at Selinsing concentrated on sulphur and lead isotopes attempting to resolve the source of metals, including gold. In this regard, the data suggest that sulphur was derived from a sedimentary local source and lead was sourced from the upper crust (Makoundi, 2012; Makoundi et al., 2014). These authors suggested a two-stage model of gold mineralisation at the Selinsing gold deposit in the Central Gold Belt. The early stage characterised by initial Au enrichment in organic-rich sediments and a late stage marked by remobilisation of Au and deposition in structural traps (Makoundi et al., 2014). At a larger scale, there was no evidence to indicate which types of sedimentary rocks are potential gold source rocks for the Malaysian mineral deposits. Answering this question is the ultimate aim of the current study.