Characterization of sand lenses embedded in tills

Famennian glaciation in the eastern side of Parnaíba Basin, Brazil: evidence of advance and retreat of glacier in Cabeças Formation

“…The detachment surface is preferentially developed in the contact between diamicton and sigmoidal sandy lobes. This contact zone, due to rheology differences, was favorable for the propagation of the movement induced by glaciers, generating a detachment surface similar to those described by van der Wateren (1986), Hindmarsh (1987), Fernlund (1988), and Kessler et al (2012). Tangential surfaces of detachment combined with tillites with sandstone pods indicate the subglacial shearing responsible by erosion and disruption of the substrate (FA1) at glacier advance periods (Boulton & Hindmarsh 1987, Kessler et al 2012.…”

“…The glacier migration caused disruption of the sand supply and further assimilation of the delta beds into the diamicton (FA2); and abrasion of crystalline and sedimentary rocks on the glacier substrate. The glacial structures generated during this stage were interpreted as compatible with those formed under the brittle-ductile regimen related to glacial advance periods (McCarroll & Rijsdijk 2003, Kessler et al 2012). ■ The third depositional phase is represented by the final stage of glacier advance, thus the ice mass was reduced and the diamicton deformation took place under glaciotectonism static conditions (Jhaer & Kruger 2001, Fig.…”

“…Partially preserved sedimentary structures in the sandstone pods are evidence of erosion and assimilation of pre-existing sedimentary deposits in the substrate (FA1) into the base of the glacier in above water melting temperature (warm permafrost). The ice in sediments porosity increases the cohesion and increases the material strength to the deformation (Waller et al 2009, Kessler et al 2012. Despite the FA2 being similar to subaqueous gravity driven flow deposits (Shanmugam 2000, Canuto et al 2010, it was interpreted as a product of subglacial erosion because it is limited by sub-horizontal detachment surface.…”

Depositional environment of the glacigenic deposits from the Holy Cross Mountains (Poland) – interpretation based on macro- and microstructure analyses

“…How ever, it can not be excluded that the very com pact lower lay ers were formed in a submarginal en vi ron ment, un der the pres sure of ice masses during their small ad vance. In such con di tions the de pos its formed as sand pock ets are stretched and at ten u ated, and trans formed into sand sheets and string ers (Kessler et al, 2012).…”

A Bayesian belief network approach for assessing uncertainty in conceptual site models at contaminated sites

“…Clay tills are common in northern Europe and parts of North America [Christiansen et al, 2008;Parker et al, 2008] and can lead to a complex system of preferential flow paths (e.g. fractures or sand lenses) in a low permeability matrix [Damgaard et al, 2013a;Damgaard et al, 2013b;Gerber et al, 2001;Hendry et al, 2004;Kessler et al, 2012;Kessler et al, 2013]. Capturing a correct conceptual understanding of such sites is crucial in risk assessment and management where predictions of contaminant breakthrough, leaching time and remedial options are required.…”