Facies analysis and palaeoecology of the Jurassic Spiti Shale Formation in the Spiti area, Northern India

Fürsich, Franz T.; Alberti, Matthias; Pandey, Dhirendra K.; Chaskar, Ketan; Bhosale, Suraj

doi:10.1016/j.jop.2021.09.001

Cited by 11 publications

(3 citation statements)

References 24 publications

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“…The dominance of black shale with occasional calc-arenite beds in F.A-II suggests greater depth than the F.A-I, where the planar laminated shale deposited from suspension falls out in a calm and quiet environment. The earlier studies on palaeoredox suggested that the depositional site was dysoxic-anoxic (Fursich et al 2021; Albert et al 2021). The absence of coarse-grained sediment in an anoxic zone infers depositional site below the wave and storm base.…”

Section: Discussionmentioning

confidence: 99%

“…The Himalayan sedimentary succession deposited along the north-eastern boundary of India in the southern hemisphere of Tethys holds crucial information on Eocambrian to Eocene (Fig. 2a; Bhargava and Singh, 2019; Fursich et al 2021; Albert et al 2021; Sun et al 2021). The Jurassic succession is mainly preserved at the inner part of the higher Himalayas, often representing the scenario during Gondwana’s disintegration.…”

Section: Geological Settingmentioning

confidence: 99%

“…The depositional sequence represents a transition from limestone to anoxic black shale (Bhargava and Singh, 2019; Fursich et al 2021; Albert et al 2021). Several studies focus on the change in palaeoclimate and ocean chemistry (Bhargava and Singh, 2019; Fursich et al 2021; Singh et al 2021), while the cause of facies transition is yet to be explored. The present study records a number of beds with soft-sediment deformations on top of the FOF.…”

Section: Introductionmentioning

confidence: 99%

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Linking the impact of seismicity on palaeogeographic evolution and sedimentary architecture: A case study from Middle Jurassic succession of Spiti Himalaya

Mandal,

Singh,

Banerjee

et al. 2023

Geol. Mag.

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The traces left by earthquakes in the unlithified sediments, recorded as soft-sediment deformation structures (SSDS), are well reconstructed as palaeo-seismic signals, while the origin of SSDS, seismic vs. Aseismic, is challenging. The present study discusses the origin of SSDS and its implications on palaeoceanography and sediment architecture. In the Middle Jurassic succession of Spiti Himalayan region in India, the topmost part of the Ferruginous Oolitic Formation (FOF) consists of four layers of SSDS and is underlain by the lower member of the Spiti Formation (SF). The sedimentary facies analysis documents the palaeogeographic shift from the middle shelf (carbonate-shale repository: FOF) to the outer shelf (black shale: lower member of SF). The SSDS layers, exhibiting load casts, ball and pillow structures, indicate gravitational instability, while syn-sedimentary faults and insitu breccia are the results of brittle deformation. The dominance of storms in depositional sites often argues for a possible triggering agent for SSDS. Therefore, it was necessary to distinguish between seismic vs. aseismic triggering agents. The lateral continuity, vertical repetition, confinement of SSDS at the top part of FOF and sharp change of facies assemblage indicate seismicity-induced syn-sediment deformation, i.e. seismite. The transition from middle shelf to outer shelf at the onset of seismite indicates that seismic impact possibly caused the rapid subsidence, resulting in the palaeogeographic shift. The rapid transgression is recorded as carbonate-shale repository to anoxic black shale. This study highlights the importance of sedimentological analysis to distinguish the seismite and its implications on palaeogeographic evolution and sedimentary architecture.

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Section: Discussionmentioning

confidence: 99%