New perspectives on the Luoquan Glaciation (Ediacaran‐Cambrian) of North China

Abstract

The Luoquan Formation provides a record of the Ediacaran-Cambrian glaciation in the North China Craton. The sedimentary record is well expressed in the Henan Province along the central China orogen, and includes a rich archive of striated pavements, diamictites, and dropstone-bearing laminites. A reappraisal of the sedimentological evolution of the Luoquan Formation notes the following features. First, striated pavements with crosscutting striations do not necessarily record multiple phases of glacial (re)advance, but more likely originate through the development of sticky spots in a palaeo-ice stream setting. The development of obstacles, basal adfreezing, or porosity variations in the subglacial substrate resulted in curvilinear and bifurcating striae, which can superficially be mistaken for crosscutting striae in isolated sections. Second, "massive" diamictites as previously described are in fact commonly weakly stratified, and there is a continuum from dropstone-bearing rhythmically bedded shales and siltstones, through stratified diamictites to massive diamictites. This continuum is believed indicative of deposition by rain out from debris rich ice for those diamictites with less pronounced stratification, in contrast to the mass flow hypothesis previously suggested. Third, the presence of large-scale, recumbent folds with associated thrusts is described at the type section. The suite of large-scale deformation structures, measuring >30 m in amplitude, is sealed by undeformed diamictites. The deformation structures are interpreted to reflect soft-sediment deformation produced through ice bulldozing. Integrating these observations, it is proposed that the Luoquan Formation was deposited in a large proglacial lake setting, with a range of ice contact to ice distal environments recognized. K E Y W O R D Scambrian, China, Ediacaran, glacial, glaciation

An Upper Ediacaran Glacial Period in Cadomia: the Granville tillite (Armorican Massif) – sedimentology, geochronology and provenance

“…Most are not very well constrained because of their age and/or that their glacigenic nature is currently under discussion (see compilations of Arnaud et al 2011;Youbi et al 2020). The two most likely ones are located on the North China craton (Le Heron et al 2018) and in Tasmania (Calver et al 2004). Another glacial deposit (Moelv diamictite) with a suggested Ediacaran age also crops out in Baltica (Bingen et al 2005), but at present available age data are not sufficient to constrain an age younger than the Gaskiers glaciation.…”

Geochronological constraints of the Huoshan Formation in the Lüliang area: Implication on the Great Unconformity in the central North China Craton

“…The carbon isotope excursion of the carbonates suggested the Dongpo Formation can be correlated with the Nanhua carbonates in South China (L. Zhang et al, 2008). However, recent studies reported the Asteridium-Heliosphaeridium-Comasphaeridium fossil assemblages, which first appeared in the Cambrian, both in the Luoquan and Dongpo formations (Le Heron et al, 2018;P. C. Wang, 2015;B.…”

“…In addition, the Great Unconformity between the Precambrian basement and Cambrian sedimentary cover, particularly in Laurentia with extensive documentation, was closely related with the dramatic change of the surface and deep geodynamic process during the Proterozoic to the Phanerozoic (Allen & Campbell, 2008;Meert & Lieberman, 2008;Olierook et al, 2019;Squire, Campbell, Allen, & Wilson, 2006). In the North China Craton (NCC), this unconformity was represented by the depositional hiatus between the Precambrian metamorphic basement and the Cambrian successions in most regions (T. C. He et al, 2016;Le Heron, Vandyk, Wu, & Li, 2018;M. Li, Vandyk, et al, 2020;Tang, Pang, Yuan, Wan, & Xiao, 2015;B.…”

“…Zheng,& Liu, 2019). However, although the consensus reached that Luoquan Formation is of Ediacaran age, the dispute in relation to the time of the Dongpo Formation is still ongoing(Le Heron et al, 2018;P. C. …”

Glendonite-Like Carbonate Aggregates from the Lower Ordovician Koporye Formation (Russian Part of the Baltic Klint): Detailed Mineralogical and Geochemical Data and Paleogeographic Implications

“…Although Cambrian-Early Ordovician climate is generally considered as a greenhouse [17,18], plenty of evidence for climate oscillations and even the presence of glaciations in the Early Cambrian and Late Cambrian have been identified in recent decades [19]. This includes the presence of tillites and abundant dropstones, as well as specific sedimentary structures (ice-push lineations and structures implying frozen sediment) in the Early Cambrian [10,20,21], and evidence for freezing conditions even in the relatively low-latitudes in the Late Cambrian [22].…”