scholarly journals Surface and subsurface reworking by storms on a Cambrian carbonate platform: evidence from limestone breccias and conglomerates

Geologos ◽  
2014 ◽  
Vol 20 (1) ◽  
pp. 13-23 ◽  
Author(s):  
Jitao Chen
Keyword(s):  
Carbonate Platform ◽  
Small Scale ◽  
Soft Sediment ◽  
Wave Loading ◽  
Carbonate Platforms ◽  
Late Cambrian ◽  
Storm Waves ◽  
Storm Wave ◽  
Waves And Currents ◽  
Sediment Deformation

Abstract Some limestone breccias and conglomerates from the Furongian (Late Cambrian) Chaomidian Formation (Shandong Province, China) were investigated in order to understand the depositional and deformational processes induced by storms. The sediments under study occur in a hummocky cross-stratified peloidal grainstone layer. The limestone conglomerates consist of well-rounded clasts that are mostly flat-lying or imbricated, and have erosional bases. They formed by surface reworking (erosion and rip-up) of thin-bedded grainstones by storm waves and currents. The limestone breccias consist of subangular to subrounded clasts of grainstone, which are often associated with small-scale grainstone clastic dykes. The breccias and dykes resulted from subsurface soft-sediment deformation (i.e., differential liquefaction and fluidization of heterogeneously cemented carbonate grains), most likely triggered by storm-wave loading. The limestone breccias and conglomerates bear important implications for understanding the reworking mechanisms of storms on ancient carbonate platforms

Non-tectonic deformations of Pleistocene sediments in the eastern Paris basin, France

2007 ◽  
Vol 178 (5) ◽  
pp. 367-381 ◽  
Author(s):  
Stéphane Baize ◽  
Michel Coulon ◽  
Christian Hibsch ◽  
Marc Cushing ◽  
Francis Lemeille ◽  
...  
Keyword(s):  
Stress Field ◽  
Regional Scale ◽  
Mass Movement ◽  
Small Scale ◽  
Soft Sediment ◽  
Paris Basin ◽  
Deformation Structures ◽  
Sediment Deformation ◽  
Soft Sediment Deformation

Abstract Deformations observed within Quaternary alluvium in the Champagne region (Paris Basin) comprise faults, folds and soft-sediment deformation structures. Their occurrence is linked to the subjacent weathered chalk. Previously interpreted as neotectonic features, the deformations are reinterpreted as karst subsidence features or/and soil displacements due to periglacial processes. Dissolution of chalk has produced superficial subsidence, explaining the geometry of some faults and their large offsets within surface deposits. The freezing-thawing cycles in the porous superficial layers have also favoured gravity instability and deformations, and this can explain local small-scale deformations but also mass movement (sliding). The seismotectonic hypothesis is rejected, because of the absence of regional faults able to generate such large co-seismic offsets. The fault directions and the apparent vertical offsets are not homogeneous at regional scale and they are often inconsistent with the Quaternary stress field. Moreover, the rooting of faults into the basement is not documented and therefore, the neotectonic origin is very doubtful.

scholarly journals Small-Scale Soft-Sediment Deformation Structures in the Cross-Bedded Coconino Sandstone (Permian; Arizona, United States); Possible Evidence for Seismic Influence

2021 ◽  
Vol 9 ◽  
Author(s):  
Leonard Brand ◽  
Sarah Maithel
Keyword(s):  
Grand Canyon ◽  
Clay Content ◽  
High Water ◽  
High Water Content ◽  
Small Scale ◽  
Soft Sediment ◽  
Deformation Structures ◽  
Sediment Deformation ◽  
Soft Sediment Deformation ◽  
The Cross

The Permian Coconino Sandstone of northern Arizona contains numerous small-scale, soft-sediment deformation structures (SSDSs). These novel structures may be indicators of paleoenvironment or sedimentary processes. These SSD are generally shallow and occur on the surfaces of cross-beds, in contrast to convoluted bedding up to tens of meters thick commonly observed in some other eolian sandstones. These differences in structures imply differences in the processes that formed the Coconino Sandstone, or differences in the underlying depositional conditions. These SSDSs occur in outcrops at the Grand Canyon, and farther south in quarries near the towns of Seligman and Ash Fork. Size, orientation, structure, sedimentary context, clay content, and porosity of the structures are described. The SSDSs occur as small folds and ridges on the paleo lee side of otherwise undisturbed cross-beds. Some are associated with small rotated sandstone blocks within the cross-beds. The structures are exposed on bedding plane surfaces and in cross-section on vertical quarry walls. A few SSDSs up to a meter thick also occur in the Coconino Sandstone, but the others are only up to a few cm thick, 2–10 cm wide, and 20 cm to 10 m long. Evidence is presented that liquidization (as fluidization or liquefaction) may have been involved in producing these features, implying a high water content in scattered locations at time of deformation, but this process also requires some stressor to trigger the deformation. Seismic events may provide a triggering mechanism. The Coconino Sandstone SSDSs represent unusual or previously overlooked small-scale features related to individual foreset surfaces.

scholarly journals Seismic and non-seismic soft-sediment deformation structures in the Proterozoic Bhander Limestone, central India

Geologos ◽  
2014 ◽  
Vol 20 (2) ◽  
pp. 89-103 ◽  
Author(s):  
Subir Sarkar ◽  
Adrita Choudhuri ◽  
Santanu Banerjee ◽  
A.J. (Tom) Van Loon ◽  
Pradip K Bose
Keyword(s):  
Central India ◽  
Small Scale ◽  
Soft Sediment ◽  
Facies Association ◽  
Deformation Structures ◽  
Basin Subsidence ◽  
Sediment Deformation ◽  
Soft Sediment Deformation ◽  
Hypersaline Lagoon ◽  
Bhander Limestone

Abstract Numerous soft-sediment deformation structures occur within the Proterozoic Bhander Limestone of an intracratonic sag basin in a 750 m long section along the Thomas River, near Maihar, central India. Part of these deformation structures have most probably a non-seismic origin, but other structures are interpreted as resulting from earthquake-induced shocks. These seismic structures are concentrated in a 60 cm thick interval, which is interpreted as three stacked seismi-tes. These three seismites are traceable over the entire length of the section. They divide the sedimentary succession in a lower part (including the seismites) deposited in a hypersaline lagoon, and an upper open-marine (shelf) part. Most of the soft-sediment deformations outside the seismite interval occur in a lagoonal intraclastic and muddy facies association. The SSDS within the seismite interval show a lateral continuity. They record simultaneous fluidisation and liquefaction. The bases of each of the three composing seismite bands are defined by small-scale shear folds, probably recording an earthquake and aftershocks. The presence of the three seismite bands at the boundary between the lagoonal and the overlying open-marine oolitic facies association suggests that the seismic event also triggered basin subsidence.

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