A novel methodological approach for thin-section description and its application to periglacially disturbed Pleistocene deposits from Danbury, Essex, UK

Abstract

Although micromorphological terminology has been evolving since 1960, there have been few attempts to create a systematic approach to the description of thin-sections which would serve as a guiding tool for inexperienced researchers, students, and all new to the field of micromorphology. In this paper we present a novel, decision tree based systematic approach for thin-section description. This new approach attempts to unify micromorphological descriptions of Quaternary deposits, regardless of the character of the deposit and the purpose of the analysis.In this research project, named ‘Hidden Ice Worlds’, the micromorphology of an 8 m thick sequence of periglacially disturbed deposits from the Royal Oak Pit, Danbury hill, Essex, UK is described. This sequence is situated on the eastern side of Danbury hill, at c. 50 m OD. Based on micromorphological analyses, a new hypothesis for the evolution of this sequence is presented. Multiple phases of physical reworking associated with freezing and thawing of the deposit, subsequent to Elsterian (Anglian) glaciation (480-420 ka BP) is proposed as the main process responsible for the evolution of the sequence. As periglacially derived deposits are usually removed from such elevated locations on hill' slopes, inversion of the topography is proposed as a necessary factor for the formation and preservation of the sequence described in this atypical location.

Middle Pleistocene ice‐marginal sedimentation at a constrained ice‐sheet margin, East Anglia, UK

“…Features such as ice-wedge casts, involutions or diapiric structures are indicative of cryoturbation relating to periglacial activity. The presence of original sedimentary structures preserved within the disturbed unit is evidence that the depositswere frozen at the time of deformation (Leszczynska et al 2011). It was also established that processes characteristic of stable environmental conditions, such as the initial stages of soil formation, occurred on a few occasions throughout the evolution of the deposit (Leszczynska et al 2011).…”

“…-The facies association of deformed diamict D3 from the Royal Oak pit was the subject of an extensive micromorphological investigation, described in detail by Leszczynska et al (2011). -The facies association of deformed diamict D3 from the Royal Oak pit was the subject of an extensive micromorphological investigation, described in detail by Leszczynska et al (2011).…”

“…-The facies association of deformed diamict D3 from the Royal Oak pit was the subject of an extensive micromorphological investigation, described in detail by Leszczynska et al (2011). It was also established that processes characteristic of stable environmental conditions, such as the initial stages of soil formation, occurred on a few occasions throughout the evolution of the deposit (Leszczynska et al 2011). It was also established that processes characteristic of stable environmental conditions, such as the initial stages of soil formation, occurred on a few occasions throughout the evolution of the deposit (Leszczynska et al 2011).…”

“…Deformed diamict facies association (D3: Ds, Fm, Fl). -The facies association of deformed diamict D3 from the Royal Oak pit was the subject of an extensive micromorphological investigation, described in detail by Leszczynska et al (2011). This facies association has been excessively disturbed by multiple freezing and thawing, together with wetting and drying cycles (Leszczynska facies association G1 facies association S1 facies association D3 m a.s.l.…”

Micromorphology of modern tills in southwestern Spitsbergen – insights into depositional and post-depositional processes

“…This statement is true for tills as well. The application of micromorphology in till research began to intensify in the 1980's (van der Meer 1987 and has continued to develop over the past three decades (e.g., van der Meer 1993van der Meer , 1996van der Meer , 1997van der Meer et al 2003;Menzies 2000;Carr 2001;Ruszczyńska-Szenajch et al 2003;Menzies et al 2006Menzies et al , 2010Evans et al 2006;Piotrowski et al 2006;Phillips 2006;Larsen et al 2006aLarsen et al , 2006bKilfeather et al 2009;Leszczynska et al 2011;van der Meer and Menzies 2011;. The inclusion of micromorphology in till research has contributed to a better understanding of till deposition conditions and the identification of a number of factors that influence the deposition mode: glacier velocity, water content, clay content, etc.…”