Road construction work of the Pan-Borneo Highway at sections of the Lambir Hills has created a few fresh temporary outcrops. Of particular importance is an excellent outcrop of the Mid-Miocene Unconformity (MMU), which we called the "White Cliff". An equally spectacular outcrop shows Lambir sandstone offset in strikeslip against a sand wedge and the older Setap Shale, at the inferred (West) Baram Line location. The outcrop is an additional data point for the Baram Line regional strike-slip system, which has been mapped previously with some confidence on both seismic and gravity data.
New outcrops of Paleozoic meta-sediments northwest of Kuala Lumpur expose the deformational effects of the Late Paleozoic-Mesozoic collisions between various Gondwana-derived continental fragments as they amalgamated to form the core of SE Asia. Over a duration of 6 months, beginning in August 2020, we conducted field trips within northern Selangor to new laterally extensive outcrops for field observations, structural mapping and to measure and log the stratigraphic section. This paper focuses on Upper Paleozoic Kenny Hill Formation outcrops in northern Selangor. The most studied is the heavily weathered Jalan Rawang-Bestari Jaya (JRBJ) outcrop, which is characterised by a steeply dipping (southwest), upward-coarsening succession of sandstones and shales interpreted as a system of ephemeral fluvial channels possibly related to Gondwana glaciation. Concretions within bedding planes and fractures were possibly formed around organic material. Less than 4 km to the east, the Scientex development has excavated fresher outcrops of the same rocks dipping to the NE. Metamorphic lineation is not present in either outcrop location. In addition, a monocline is exposed at outcrop location number 3 nearby. Finally, at Bukit Botak, 14 km to the southwest, a system of westward verging thrust faults, back thrusts and normal faults can be viewed and an angular unconformity or decollement marks the contact between the Upper and Lower Paleozoic. These laterally extensive outcrops are rare and are quickly subject to intense tropical weathering, the encroachment of jungle vegetation and urban development. Historic mapping and prior stratigraphic, structural, and petrographic studies have been conducted in the area, but these relied on poor exposures. As suburban development escalates in the area, we hope that new outcrops, featuring multi-dimensional views of these formations, such as the four described in this paper, will complement the earlier work.
The Bario/Kelabit Highlands, located in northern Sarawak is famous for its rice. One of Bario's hidden treasures, however, is its salt, produced from the many salt springs in the area but sold in small quantities at the local marketplace such that its existence is not well known outside of Sarawak. The Bario salt is probably of non-marine origin but its actual origin is not clear. A new salt analysis, in the context with older salt spring data, has enabled a comparison with other non-marine salts. In particular, the presence of borate and lithium points to potential affinities with non-marine highland salts, such as those found in Argentina, Bolivia, Nevada and Tibet, as well as with phreatic brine salt such as the Jadar deposit in Serbia. The marked content of iodine makes allusion to brines in the vicinity of hydrocarbon-bearing reservoirs. Given that the Bario salt contains hardly any sulphate, and very little calcium, the source of the salt is unlikely to be an evaporite-bearing rock in the subsurface as previously thought. Nonetheless, there should be more fieldwork conducted and analyses made on the highland salt deposits and associated brines in northern Sarawak to provide a better understanding of their geochemical composition and origin.
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