TY - JOUR
T1 - Temperate glaciation on a Snowball Earth
T2 - Glaciological and palaeogeographic insights from the Cryogenian Yuermeinak Formation of NW China
AU - Vandyk, Thomas Matthew
AU - Wu, Guanghui
AU - Davies, Bethan
AU - Xiao, Yang
AU - Li, Meng
AU - Shields-Zhou, Graham
AU - le Heron, Daniel
PY - 2019/9/1
Y1 - 2019/9/1
N2 - Extreme glaciation is the hallmark of the Cryogenian Period and understanding the behaviour and configuration of its constituent ice bodies is essential for environmental reconstructions. Thermal regime is one of the most important controls of glacial behaviour and subglacially striated surfaces are one of the very few means of determining an ancient temperate thermal regime. Unfortunately, due to a preservational bias of basinal over subglacial facies and the fragility of mm-scale striae, these surfaces are rarely preserved. In this context we present sedimentological and detrital zircon detail of a fortuitously preserved Cryogenian (Marinoan) outcrop on the Tarim Craton, NW China. The Yuermeinak Formation preserves not only a subglacially striated surface and palaeotopography but also a thin locally developed subglacial facies, indicating grounded ice. The remaining formation reveals glacial retreat and deposition of predominantly supraglacially-sourced debris within a dynamic, open-water, ice-proximal proglacial environment. This debris comprises dropstone-bearing shales punctuated by turbidites to debrites. Integrating our findings with published hypotheses for the tectonic and palaeogeographic development of the Tarim craton, we are able to present a first attempt at reconstruction of the palaeogeographic context of the Marinoan glaciation on the northern Tarim margin.
AB - Extreme glaciation is the hallmark of the Cryogenian Period and understanding the behaviour and configuration of its constituent ice bodies is essential for environmental reconstructions. Thermal regime is one of the most important controls of glacial behaviour and subglacially striated surfaces are one of the very few means of determining an ancient temperate thermal regime. Unfortunately, due to a preservational bias of basinal over subglacial facies and the fragility of mm-scale striae, these surfaces are rarely preserved. In this context we present sedimentological and detrital zircon detail of a fortuitously preserved Cryogenian (Marinoan) outcrop on the Tarim Craton, NW China. The Yuermeinak Formation preserves not only a subglacially striated surface and palaeotopography but also a thin locally developed subglacial facies, indicating grounded ice. The remaining formation reveals glacial retreat and deposition of predominantly supraglacially-sourced debris within a dynamic, open-water, ice-proximal proglacial environment. This debris comprises dropstone-bearing shales punctuated by turbidites to debrites. Integrating our findings with published hypotheses for the tectonic and palaeogeographic development of the Tarim craton, we are able to present a first attempt at reconstruction of the palaeogeographic context of the Marinoan glaciation on the northern Tarim margin.
U2 - 10.1016/j.precamres.2019.105362
DO - 10.1016/j.precamres.2019.105362
M3 - Article
SN - 0301-9268
VL - 331
SP - 1
EP - 42
JO - Precambrian Research
JF - Precambrian Research
M1 - 105362
ER -