Jurassic–Lower Cretaceous sequence stratigraphy and allogenic controls in proximal terrestrial environments (Southern Junggar Basin, NW China)

Abstract

The terrestrial sequence stratigraphy in proximal terrestrial environments is different from its counterpart in distal terrestrial and marine environments. The Southern Junggar Basin in NW China has preserved well‐exposed proximal terrestrial outcrops and its Jurassic–Cretaceous sequence boundary remains contentious. The goal of this paper is to (a) establish a model of allogenic‐controlling mechanisms of a proximal terrestrial sequence, (b) investigate the Jurassic–Cretaceous sequence boundary, (c) the Jurassic climate, and (d) tectonic movements in Central Asia. The sequence stratigraphic framework was established assisted by the determination of the accommodation space/sediment supply (A/S) ratio, including two second‐order sequences (SS) and six third‐order sequences (SQ) in the Jurassic, as well as a second‐order sequence in the Cretaceous. SS1 was mainly controlled by a warm and humid climate and lake level fluctuations in a weak extensional tectonic setting; SS2 was mainly controlled by an arid climate and compressional tectonic movements; SS3 was mainly controlled by a semi‐humid climate and lake transgression in a stable tectonic setting. Additionally, the Jurassic–Cretaceous sequence boundary was distinguished within the Kalazha Formation based on its sedimentary characteristics, sedimentary evolution, and different allogenic controls. It is concluded that the proximal terrestrial sequences exhibit rapid sedimentary facies change, thick coarse‐grained sediments, and multiple provenances. Climate, tectonic movements, and lake level fluctuation dominate in different stages of basin evolution. Moreover, the sediment supply is more emphasized, and the accommodation space/sediment supply ratio, which corresponds to different channel geometry types, plays a critical role in identifying system tracts and sequence stratigraphic surfaces.

Facies distribution and depositional cycles in lacustrine and palustrine carbonates: The Lutetian–Aquitanian record in the Paris Basin

“…Three types of stratigraphic surfaces used in marine areas can be applied to continental deposits (Hanneman & Wideman, 2010): subaerial unconformities, correlative conformities and maximum flooding surfaces. Units are bounded by sequence boundaries (subaerial unconformities and their correlative conformities), which represent the shallowest environment recorded within a sequence and coincide with shifts in stacking patterns between shallowing‐upward and deepening‐upward trends (Strecker et al., 1999; Changsong et al., 2001; Keighley et al., 2003; Hanneman & Wideman, 2010; Pérez‐Rivaréz et al., 2018; Deschamps et al., 2020; Guan et al., 2021; Melo et al., 2021; Lettéron et al., 2022). Subaerial unconformities were identified by surfaces characterised by features such as erosion karstification or palaeosoils occurrence—whereas correlative conformities are surfaces that were not (Hanneman & Wideman, 2010).…”

“…In the succession of palustrine deposits encountered in this study, the beds with the least evidence of pedogenic modifications were interpreted as MFS, recording the periods when the water level was highest. Subaerial unconformities, correlative conformities and maximum flooding surfaces separate transgressive systems tracts, characterised by deepening‐upward facies, and highstand systems tracts, characterised by shallowing‐upwards facies (Strecker et al., 1999; Bohacs et al., 2000; Changsong et al., 2001; Keighley et al., 2003; Bohacs et al., 2007; Deschamps et al., 2020; Guan et al., 2021). The nomenclature of the short‐term and long‐term surfaces used in this work for the Cenozoic of the Paris Basin was initially defined by Briais (2015).…”

Sedimentary and Source-to-Sink Evolution of Intracontinental Basins: Implications for tectonic and Climate Evolution in the Late Mesozoic (Southern Junggar Basin, NW China)

“…(Guan et al, 2020). The man (170 cm) for scale; (C) Sikeshu River section; (D) Quergou section (Guan et al, 2021). The man (175 cm) for scale; (E) Dongwoz section; (F) Jiangong mine section (G, H) Wangjiazhuang section.…”

“…The western part of the Bogda Orogenic Belt exhibits slightly positive relief, which cannot block the sediments from the Tianshan Orogenic Belt (Fang et al, 2019). Sediments were transported from the North Tianshan to the Fukang fault belt (catchment 3), which is evidenced by northward paleocurrents and fluvio-lacustrine environments (Fang et al, 2019;Guan et al, 2021).…”

“…FIGURE 5 | Sedimentary characteristics of the Kalazha Formation in the northern piedmont of the Tianshan Orogenic Belt (a-f, l, m) and Bogda Orogenic Belt (g-k, n, o) in the Southern Junggar Basin (A, B) Manasi section(Guan et al, 2020). The man (170 cm) for scale; (C) Sikeshu River section; (D) Quergou section(Guan et al, 2021). The man (175 cm) for scale; (E) Dongwoz section; (F) Jiangong mine section (G, H) Wangjiazhuang section.…”