Paleoenvironments of the evolving Pliocene to early Pleistocene foreland basin in northwestern Taiwan: An example from the Dahan River section

Abstract

The overriding of the Luzon volcanic arc atop the underlying Chinese rifted‐continental margin has caused the formation of the Taiwan mountain belts and a peripheral foreland basin west of the orogen since the late Miocene. In this study, lithofacies analysis and calcareous nannofossil biostratigraphic investigations of the Dahan River section in northwestern (NW) Taiwan were performed. Our results offer insights into the temporal evolution of the sedimentary environments and the competing effects of the sedimentation and basin tectonics of the NW Taiwan foreland basin from the Pliocene to early Pleistocene. Nannofossil biostratigraphic studies showed that the upper Kueichulin Formation and the overlying Chinshui Shale can be assigned to the NN15 biozone of the Pliocene age, and the Cholan Formation pertains to NN16–NN18 of the early Pleistocene. The NN15–NN16 boundary coincides roughly with the boundary of the Chinshui Shale and Cholan Formation. We recognized three major sedimentary environments in the studied foreland succession comprising the upper Kueichulin Formation, Chinshui Shale, Cholan Formation and Yangmei Formation, in ascending order. During the deposition of the upper Kueichulin Formation in the early Pliocene, the dominant environment was a wave‐ and tide‐influenced open marine setting. During the late Pliocene, the environment deepened to an outer‐offshore setting when the sediments of Chinshui Shale were accumulated. In the Pleistocene, the environment then shallowed to wave‐dominated estuaries during the deposition of the lower Cholan Formation, and the basin was rapidly filled, generating a meandering and sandy braided river environment during the deposition of the upper Cholan to the Yangmei Formation. In summary, the evolution of sedimentary environments in the studied succession shows a deepening then a shallowing and coarsening upward trend during the period from the Pliocene to the Pleistocene, spanning the age from approximately 4 to 1 Ma.

Physical simulation of remaining oil distribution in the 3rd-order architecture unit in beach sand reservoir

“…Further analysis and characteristics of the outcrop in the Donghe sandstone of the HD4 oilfield show that the lithology of layer interface is mainly mudstone or silty mudstone (Figure 1), which show notable differences in the weathering of the outcrop and possess a clear reservoir's structural characteristics in beach sand facies (Figure 1). The architecture of layered reservoirs is more common in backshore dams, beach sand shoals, channels, tidal flats, and other depositional facies (Fan et al, 2014;Pan et al, 2015;Zahid et al, 2021;Fawad et al, 2022;Peter et al, 2017). Due to the difference in origin, the thickness of a single layer and the number of interlayers is different.…”

Multi‐proxy evidence for rapidly shifting sediment sources to the Taiwan Western Foreland Basin at the Miocene–Pliocene transition

“…The WFB is characterized by both high-accommodation and high-sedimentation rates; sediment accumulation rates exceeded 400 m per million years in the early to mid-Pliocene and 1000 m per million years in the late Pleistocene (Chang & Chi, 1983;Chen et al, 1992;Covey, 1986;Simoes & Avouac, 2006;Vaucher et al, 2021). Late Miocene to Pliocene sedimentary strata of the Kueichulin Formation were deposited in the WFB during the early stages of the collision (Lin et al, 2003;Yu & Chou, 2001) and in mainly shallow-marine environments (Castelltort et al, 2011;Covey, 1986;Dashtgard et al, 2020Dashtgard et al, , 2021Nagel et al, 2013;Pan et al, 2015). The Kueichulin Formation overlies the Nanchuang Formation and grades both upwards and southwards into the Chinshui Shale (Figure 3; Castelltort et al, 2011).…”

“…6.5 Ma) and formed the 330 km long, 100 km wide orogenic belt that comprises the majority of Taiwan. The orogenic belt continues to uplift at a rate of approximately 5–7 mm year −1 (Figure 2a; Castelltort et al, 2011; Covey, 1986; Lin et al, 2003; Lin & Watts, 2002; Nagel et al, 2018; Pan et al, 2015).…”

Late Miocene otoliths from northern Taiwan: insights into the rarely known Neogene coastal fish community of the subtropical northwest Pacific

“…On the basis of a few otoliths from the same area, Lin (2010b) first interpreted the palaeoenvironment as being reflective of a shallow coastal sea. The sedimentary environment of the Tapu Formation is generally littoral to the offshore transition zone (Pan et al 2015;Chen and Yu 2016). These lines of evidence and the otoliths described herein, along with the associated marine fossils (see above, Other associated fossils), allow us to infer that in the late Miocene, the Shulin area was a coastal and estuary palaeoenvironment, particularly a shallow water environment with gentle topography covered by muddy or sandy bottoms.…”