Oligocene-Miocene drainage evolution of NW Borneo: Stratigraphy, sedimentology and provenance of Tatau-Nyalau province sediments

Abstract

Clastic sediments of Oligocene to Lower Miocene age form a major thick and widespread sequence in the Tatau-Nyalau province of the north Sarawak Miri Zone. New light and heavy mineral data, U-Pb detrital zircon geochronology and biostratigraphy are used to identify the age, depositional environment, provenance and potential sources of sediment to reconstruct the drainage evolution of NW Borneo. Based on the biostratigraphic ages, depositional environments and provenance characteristics we modify previous stratigraphy and divide the Oligocene to Lower Miocene sequences into the Nyalau Formation (Biban Sandstone Member and Upper Nyalau Member), Kakus Unit, and Merit-Pila Formation. Two dominant source provinces were identified: the Malay-Thai Tin Belt which supplied sediments dominated by Permian-Triassic zircons, and the Schwaner Mountains of central Borneo which is identified by abundant Cretaceous zircons. Sediments either came directly, or were recycled from older sedimentary rocks, from these sources. The Sunda River deposited the Nyalau Formation during the Oligocene to Early Miocene with a dominant Malay-Thai Tin Belt source. The 2 Merit-Pila Formation of the Sibu Zone was deposited contemporaneously by a proto-Rajang River that drained Central Borneo (recycling the Rajang Group and Schwaner granitoids). Between c. 17 Ma the Sunda River system terminated and sedimentation was dominated by the northward prograding proto-Rajang River delta, depositing the Kakus Unit in the Miri Zone. This drainage system was active until the Late Miocene, before further uplift of Borneo terminated most sedimentation in the onshore part of present-day Borneo.

A tuffaceous volcaniclastic turbidite bed of Early Miocene age in the Temburong Formation of Labuan, North‐West Borneo and its implications for the Proto‐South China Sea subduction in the Burdigalian

“…However, detrital zircon U‐Pb data for the Oligocene part of the WCF are dominated by Permo‐Triassic zircons (van Hattum et al, 2013) whilst the contribution of Cretaceous zircons is subordinate, clearly different from the Temburong Formation (Figure 15). Similar Permo‐Triassic zircon age‐dominant successions occur in the upper part of the Oligocene Tatau Formation and the Oligocene to early Miocene Nyalau Formation (Breitfeld et al, 2020a; Hennig‐Breitfeld et al, 2019), which are also part of the westerly source system that deposited the Crocker Formation. A Cretaceous‐dominated zircon age population was reported in the Eocene and older successions, e.g.…”

“…It is unconformably overlain by the shallow marine clastic Layang‐Layangan Beds (Madon, 1994). The unconformity directly above the Temburong Formation is considered to be the TCU and correlated with the slightly younger top Nyalau Unconformity of ca 17 Ma in Sarawak (Breitfeld et al, 2020a; Hennig‐Breitfeld et al, 2019). This unconformity is not visible on the island of Labuan as either erosion or vegetation obscure exposures.…”

“…The dominance of Cretaceous zircons in the Temburong Formation indicates an important switch in source provenance during the early Miocene from the Crocker Formation to the Temburong Formation which is not apparent in the depositional environment of the Crocker and Temburong formations. Hennig‐Breitfeld et al (2019) and Breitfeld et al (2020a) interpreted the Permian and Triassic‐dominated successions to be derived mainly from East Malaya or Indochina via a ‘Sunda River’ with only minor input from central and southern Borneo whilst van Hattum et al (2013) suggested a fluvial system from East Malaya passing through western Borneo. However, such direct derivations are unlikely in the Late Oligocene to Early Miocene since the inferred 'Sunda River' would have to flow across the rifts of the Malay Basin and the highlands of the Natuna Arch, probably an upland area at that time (Collins et al, 1996; Jong et al, 2017; Kessler & Jong, 2016; Murray & Dorobek, 2004; Shoup et al, 2013; Wirojudo & Wongsosntiko, 1985), and are more probably derived by re‐cycling.…”

“…Regionally, rifting ceased across the eastern Gulf of Thailand (Khmer, Pattani, North Malay basins), Malay, Qiongdongnan, Song Hong/Yinggehai, Central Sumatra, South Sumatra and West Java basins, whilst central Borneo began to emerge (Morley et al, 2016; Shoup et al, 2013). Central Borneo uplift is reflected offshore in the development of northward‐prograding deltas within Sarawak Cycle II/III in areas such as the offshore Balingian province (Hassan et al, 2017; Madon et al, 2013) and onshore in provenance changes from the Nyalau Formation to the overlying Kakus and Balingian formations attributed to the Nyalau Unconformity (Breitfeld et al, 2020a; Hennig‐Breitfel et al, 2019). Deltas also built out to the east in northern Luconia, epitomised by the Mulu Delta, and also in Vietnam, with the Dua Formation Delta in the Nam Con Son Basin (Lee et al, 2001).…”

Supplemental Material: Fingerprinting sand from Asian rivers to the deep central South China Sea since the Late Miocene

“…Compilation of published detrital zircon U-Pb ages along with sampling information and references from drainage sediments and bedrocks of modern potential provenances surrounding the South China Sea. Samples are grouped into 11 source areas, including West Taiwan (Chen et al, 2019;Deng et al, 2017), Coastal Southeast China (Chen et al, 2019;Xu et al, 2014b;Zhang et al, 2017), Pearl River (He et al, 2020;Liu et al, 2017;Xu et al, 2007;Zhao et al, 2015), Hainan (Cao et al, 2015;Wang et al, 2015;Xu et al, 2014a), Red River (Bodet and Schärer, 2000;Clift et al, 2006;Fyhn et al, 2019;Hoang et al, 2009;Wang et al, 2018), North Palawan (Cao et al, 2020Padrones et al, 2017;Shao et al, 2017;Suggate et al, 2014;Walia et al, 2012), East Vietnam (Fyhn et al, 2019Jonell et al, 2017;Usuki et al, 2013;Wang et al, 2018), Mekong River (Bodet and Schärer, 2000;Clift et al, 2006), Northwest Borneo (Breitfeld and Hall, 2018;Breitfeld et al, 2017;Breitfeld et al, 2020;Galin et al, 2017;Hennig-Breitfeld et al, 2019), Malay Peninsula (Sevastjanova et al, 2011), Southeast Sumatra (Zhang et al, 2019). Published age data, if available, are filtered with a cutoff criterion of  10% discordance and  10% uncertainty (1).…”