scholarly journals Soft sediments deformation structures: Implication for draining of Paleo-Kathmandu Lake

2015 ◽  
Vol 49 (1) ◽  
pp. 41-48
Author(s):  
Mukunda Raj Paudel
Keyword(s):  
Late Pleistocene ◽  
Gravitational Instability ◽  
Experimental Studies ◽  
Tectonic Activity ◽  
Soft Sediment ◽  
Delta Front ◽  
Soft Sediments ◽  
Deformation Structures ◽  
Sediment Deformation ◽  
Soft Sediment Deformation

Kathmandu basin is one of the Quaternary intermontane basins in the central Nepal Himalaya. It is bounded by several faults on both southern and northern margins. The basin is filled with Plio-Pliestocene terrestrial sediments and their characteristics indicate four types of unconsolidated successions within the basin. These are before lake succession, during lake succession, draining stage lake succession and fluvial succession. Late Pleistocene aged Sunakothi Formation crops out along the southern part of the basin. It is a typical fluviolacustrine delta succession that extended from 1390 m in the southern margin to nearly 1300 m toward center of the basin. It is composed by poorly consolidated sand, gravelly sand, silt and mud beds. Various soft-sediment deformation structures occur in the formation, especially in fine- to medium –grained sands, silts and mud: load structures, flame structures, clastic dikes (sand dike), disturbed layers, convolute beds, slumps and synsedimentary faulting. The deformation mechanism and driving force for the soft-sediment deformation are related, essentially, to gravitational instability, dewatering, liquefaction and brittle deformation. Field data and the wide lateral extent of the structures as well as regional geological data show that most of the deformation is related to seismicity and the structures are interpreted as seismites. In addition, there have also been experimental studies undertaken by various authors within the different sedimentary basin. Soft-sediments deformation structure in Kathmandu basin are mainly considered to be part of the initial diagenetic changes of the sediments and include: Slump structure which occurred on the slope like delta-front area, dewatering structures which occurred by the processes of upward escape of water commonly due to loading, load structures which occurred due to density contrasts between sand and underlying wet mud. The existence of seismites in the Sunakothi Formation is evidence of continuing tectonic activity in the study area during the late Pleistocene and is a main factor for draining of the Paleo- Kathmandu lake water.

scholarly journals Soft-Sediment Deformation Structures Interpreted as Seismites in the Kolankaya Formation, Denizli Basin (SW Turkey)

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Savaş Topal ◽  
Mehmet Özkul
Keyword(s):  
Gravitational Instability ◽  
Tectonic Activity ◽  
Normal Faults ◽  
Soft Sediment ◽  
Brittle Deformation ◽  
Deformation Structures ◽  
Sw Turkey ◽  
Lateral Extent ◽  
Sediment Deformation ◽  
Soft Sediment Deformation

The NW-trending Denizli basin of the SW Turkey is one of the neotectonic grabens in the Aegean extensional province. It is bounded by normal faults on both southern and northern margins. The basin is filled by Neogene and Quaternary terrestrial deposits. Late Miocene- Late Pliocene aged Kolankaya formation crops out along the NW trending Karakova uplift in the Denizli basin. It is a typical fluviolacustrine succession that thickens and coarsens upward, comprising poorly consolidated sand, gravelly sand, siltstone and marl. Various soft-sediment deformation structures occur in the formation, especially in fine- to medium grained sands, silts and marls: load structures, flame structures, clastic dikes (sand and gravely-sand dike), disturbed layers, laminated convolute beds, slumps and synsedimentary faulting. The deformation mechanism and driving force for the soft-sediment deformation are related essentially to gravitational instability, dewatering, liquefaction-liquidization, and brittle deformation. Field data and the wide lateral extent of the structures as well as regional geological data show that most of the deformation is related to seismicity and the structures are interpreted as seismites. The existence of seismites in the Kolankaya Formation is evidence for continuing tectonic activity in the study area during the Neogene and is consistent with the occurrence of the paleoearthquakes of magnitude >5.

scholarly journals Processes and evolution of the Pleistocene coastal sedimentary succession of Es Codolar (Southern Eivissa, Balearic Islands, Western Mediterranean): insights from soft sediment deformation structures.

2021 ◽  
Author(s):  
Laura del Valle Villalonga ◽  
Francesc Pomar ◽  
Joan J Fornós ◽  
Bernadí Gelabert ◽  
Alida Timar-Gabor
Keyword(s):  
Late Pleistocene ◽  
Western Mediterranean ◽  
Alluvial Fan ◽  
Soft Sediment ◽  
Sea Level Changes ◽  
Deformation Structures ◽  
Depositional Processes ◽  
Stratigraphic Architecture ◽  
Sediment Deformation ◽  
Soft Sediment Deformation

Abstract We analyze the evolution of the undeformed Middle to Late Pleistocene deposits of Es Codolar (Southern Eivissa, Western Mediterranean). The outcrop records a succession characterized by the alternation of aeolian, colluvial and alluvial fan deposits and palaeosols that result in a complex stratigraphic architecture. In this area, aeolian beds, colluvial deposits and palaeosols are exposed along sea-cliffs for almost 500 m, allowing detailed descriptions both of the general sedimentological and geomorphological features of the Middle to Late Pleistocene deposits. Several different types of soft-sediment deformation structures are described (Load-casts structures, injection structures, water-scape structures, rizoconcretions), which will help us in the understanding of the climatic evolution and the syn and post-depositional processes. In this way, main processes triggering the formation of these structures seem to be sea level changes together with a wetter environment during warmer climatic episodes.

scholarly journals Late Pleistocene-Holocene earthquake-induced slumps and soft-sediment deformation structures in the Acequion River valley, Central Precordillera, Argentina

Geologos ◽  
2014 ◽  
Vol 20 (2) ◽  
pp. 147-156 ◽  
Author(s):  
Laura P Perucca ◽  
Enrique Godoy ◽  
Ana Pantano
Keyword(s):  
Late Pleistocene ◽  
Large Scale ◽  
Spatial Relationship ◽  
River Valley ◽  
Fault System ◽  
Soft Sediment ◽  
Deformation Structures ◽  
Central Western Argentina ◽  
Sediment Deformation ◽  
Soft Sediment Deformation

Abstract Evidence of earthquake-induced liquefaction features in the Acequión river valley, central western Argentina, is analysed. Well-preserved soft-sediment deformation structures are present in Late Pleistocene deposits; they include two large slumps and several sand dikes, convolutions, pseudonodules, faults, dish structures and diapirs in the basal part of a shallow-lacustrine succession in the El Acequión River area. The water-saturated state of these sediments favoured deformation. All structures were studied in a natural trench created as a result of erosion by a tributary of the Acequión River, called El Mono Creek. They form part of a large-scale slump system. Two slumps occur in the western portion of the trench and must have moved towards the ENE (70°), where the depocentre of the Boca del Acequión area is situated. Considering the spatial relationship with Quaternary faults, the slumps are interpreted as being due to a seismic event. The thickest dikes in the El Mono Creek trench occur in the eastern portion of the trench, indicating that the responsible earthquake was located to the east of the study area, probably at the Cerro Salinas fault system zone. The slumps, sand dikes and other soft-sediment deformation features are interpreted as having been triggered by earthquakes, thus providing a preliminary palaeoseismic record of the Cerro Salinas fault system and extending the record of moderate-to high-magnitude earthquakes in central western Argentina to the Late Pleistocene.

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