Diamictite and Beyond: Understanding Sedimentary Proxies of Glaciation and Their Paleoclimatic Implications

Sedimentary proxies attest to the activity of glaciers and ice sheets in ancient and modern landscapes. These typically include diamict(ite) (a descriptive name for non-sorted terrigenous sediment), but also striated surfaces and clasts, lonestones, deformation structures and large-scale landforms, which inform paleoclimatic models through estimations of ice extent, thermal regime, paleo-ice flow directions, and glacial cyclicity. These proxies have been used, for instance, as support for dramatic climatic events such as Snowball Earth. However, the use of sedimentary proxies of glaciation involves uncertainty because similar geological products can be non-glacial, be generated in different glacial sub-environments or be formed by cold-climate phenomena other than glacial ice. The potential misinterpretation of glacial imprints in the rock record may lead to over/underestimation of ice cover and, by consequence, inaccurate paleoclimatic reconstructions.

This Research Topic intends to gather sedimentologists and geomorphologists around the goal of critically evaluating sedimentary proxies commonly used to recognize, quantify, and model past glaciations throughout Earth's history. This goal covers both deep time (pre-Pleistocene) successions, in which the glacial signature is fragmentary, not straightforward and, thus, subject to controversy, and Quaternary to modern glacial environments, which serve as analogues for older glacial environments and from which glacial facies models are derived.

Authors are encouraged to contribute with study cases and reviews that critically explore diamict(ite) and other classic proxies for glaciation and cold climates, aiming to build a solid and updated sedimentological approach to interrogating the past and present cryosphere. Suggested themes include (but are not limited to) the following:

• Diamict(ite) successions and the distinction between subglacial, ice-marginal, glaciogenic mass-flow, and non-glaciogenic diamictite;
• Glacial surfaces, landforms and paleovalleys;
• Clast striation, faceting, shaping, and breakage;
• Meltwater-fed depositional systems, facies, and processes;
• Emplacement of lonestones by glacial and non-glacial processes;
• Erosion and deformation by floating ice versus subglacial phenomena;
• Cryoturbation and freeze/thaw-related phenomena in the sedimentary record;
• Glaciotectonism, its products and their distinction from slump-related deformation;
• Ichnology and paleoecology of glacial environments;
• Micromorphology of glacial sediments and surfaces;
• Glacial sequences and the stratigraphic signature and chronology of glacial cycles;
• Reconstruction of paleo-ice flow, paleo-ice margins, and glacial paleogeography; and
• New methods and techniques applied to glacial deposits and landforms.

This Research Topic has been realized in collaboration with Dr. Kirsten Kennedy, Postdoc Researcher at University of Toronto.”