New findings regarding the Fen‐Wei Graben on the southeastern margin of the Ordos Block: Evidence from the Cenozoic sedimentary record from the borehole

Abstract

In the Cenozoic, fault-related basins, including the Wei River, Lingbao and Linfen basins, developed on the southeast margin of the Ordos Block. Based on the latest drilling data and previous research results, this article analysed the evolutionary processes, temporal and spatial relationships and tectonic background of these basins, and obtained the following results: (a) The Wei River Basin and the Lingbao Basin belong to a unified basin, which formed in the Palaeocene and developed gradually from east to west. (b) The Linfen Basin formed in the late Miocene and developed gradually from southwest to northeast. (c) The evolution of the basin systems was dominated by the westward subduction of the Pacific Plate in the Palaeogene and then by a combination effects of the subduction of the Pacific Plate and the uplift of the Tibetan Plateau. (d) The so-called Fen-Wei Graben is not supported by the different geological evolutionary histories of the Wei River Basin and the Linfen Basin.

Initiation and Evolution of the Shanxi Rift System in North China: Evidence From Low‐Temperature Thermochronology in a Plate Reconstruction Framework

“…This school of thought attributes Pliocene initiation of the SRS (Li et al., 1998; SSB, 1988; Xu & Ma, 1992; Xu et al., 1993) to the northward expansion of the Tibetan Plateau during India‐Eurasia collision (e.g., Molnar & Tapponnier, 1977; Peltzer et al., 1985; Tapponnier et al., 1982). However, this model is at odds with several observations, including (1) basal deposits in the southern SRS (i.e., Weihe, Yuncheng, and Linfen Basins) that are of middle Eocene in age (Bellier et al., 1988; Fan et al., 2020; Zhao et al., 2019); (2) multiphase planation surfaces preserved on rift shoulders (Lüliang Shan and Taihang Shan mountains) which suggest multiple cycles of rapid uplift and tectonic quiescence (Wu et al., 2017); (3) multiple episodes of accelerated exhumation during the Eocene‐Early Oligocene and Miocene‐Quaternary, as revealed by low‐temperature thermochronology ages from the Wutai Shan of the northern SRS (Cao et al., 2015; Chang et al., 2019; Clinkscales et al., 2020; Qing et al., 2008) and the North Qinling mountains of the southern SRS (Chen et al., 2015; Heberer et al., 2014; Hu et al., 2006; Liu et al., 2013); and (4) kinematic reorganization of deformation along the present‐day northeastern margin of the Tibetan Plateau, from widespread extension in the Eocene to contraction in the Late Miocene (Fan et al., 2019; Wang et al., 2013, 2016). These observations suggest that the timing of initial extension along the SRS and the subsequent space‐time patterns of deformation may be more complex than previously thought.…”

“…Sedimentary records exhibit similar timing of basin deposition and rift flank exhumation in the southern SRS (e.g., Li et al., 1998; Shi et al., 2020, and references therein). The Middle‐late Eocene Honghe Formation is preserved as basal deposits in the Weihe Basin (Figures 1 and 8a) (Bellier et al., 1988; Fan et al., 2020), which can be readily interpreted as the initial syn‐rift deposits. To the east, Zhao et al.…”

“…Sedimentary records exhibit similar timing of basin deposition and rift flank exhumation in the southern SRS (e.g., Li et al, 1998;Shi et al, 2020, and references therein). The Middle-late Eocene Honghe Formation is preserved as basal deposits in the Weihe Basin (Figures 1 and 8a) (Bellier et al, 1988;Fan et al, 2020), which can be readily interpreted as the initial syn-rift deposits. To the east, Zhao et al (2019) synthesized >50 boreholes and showed that Eocene strata are also preserved in some localized depressions in the Yuncheng and Linfen Basins, suggesting that the two basins had already formed by the Eocene.…”

“…The age of basal sedimentary deposits found so far in the northern and central SRS is late Neogene (e.g., Li et al., 1998; SSB, 1988; Xu & Ma, 1992; Xu et al., 1993). By contrast, the Weihe, Yuncheng, and Linfen Basins of the southern SRS contains Eocene‐aged basal sediments (Bellier et al., 1988; Fan et al., 2020; Zhao et al., 2019). Faults along the SRS have hosted some of the most devastating midcontinental earthquakes in human history, and modern and paleo‐seismicity show that the latest episode of faulting and footwall exhumation is still ongoing (Liu et al., 2011; SSB, 1988; Xu & Ma, 1992; Xu et al., 1993).…”

Fractal and Multifractal Characteristics of Lineaments in the Qianhe Graben and Its Tectonic Significance Using Remote Sensing Images

“…This region grew rapidly in the Liupan-Longxi Block because of the accelerated extension and structural deformation of the northeastern margin of the Qinghai-Tibet Plateau since the Middle Pleistocene [56]. In the Qianhe Graben, the highest elevation is 2735 m; after flowing through the central loess terrace, the altitude decreases to 548 m. The area with the highest topographic fluctuation is located in the bedrock area on the southern Qianhe Graben and the loess ridge on the northern area, whereas, in the middle part, the loess terrace valley has smaller topographic relief, and the relative altitude between the bedrock area and the terrace valley is over 1000 m. A vast number of valleys, ridges, and other lineaments are created under this context by cutting rivers and rising mountains.…”