High-resolution U-Pb dating of the Croles Hill Diamictite, Tasmania: Near-synchroneity of widely separated mid-Ediacaran glacial deposits

IF 2.7 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research Pub Date : 2026-01-01 Epub Date: 2025-11-14 DOI:10.1016/j.precamres.2025.107958

C.R. Calver , G.V. Cumming , G.P. Halverson , J.L. Crowley , N.J. Roberts , M. Schmitz

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引用次数: 0

Abstract

Ediacaran glacial deposits are widespread, but their distribution in space and time is still poorly understood, hindering global correlation and a better understanding of their association with environmental and biological change. Of these deposits, the Gaskiers Formation and nearby Trinity Diamictite in eastern Newfoundland are the best constrained radiometrically at ca. 579––581 Ma, although recent evidence suggests glaciation initiated several million years earlier. Here we report two new U-Pb (zircon) CA-ID-TIMS dates on rhyodacite units immediately below, and within the Croles Hill Diamictite in northwest Tasmania previously interpreted as glacial in origin: 579.20 ± 0.09 Ma and 578.86 ± 0.23 Ma respectively. These ages make the Croles Hill Diamictite slightly younger than the Gaskiers Formation (>579.88 ± 0.44 Ma) but permit correlation with the Trinity Diamictite. Deposition of all three diamictites took place in a narrow (<2.7 m.y.) temporal window. Features consistent with a glacial origin for the Croles Hill Diamictite include rare, laminated mudstones with dropstones, a single, consistent stratigraphic position within the Togari Group, and compositional diversity of clasts.

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塔斯马尼亚克罗尔斯山二晶岩的高分辨率U-Pb测年：广泛分离的中埃迪卡拉纪冰川沉积物的近同步性

埃迪卡拉纪冰川沉积物分布广泛，但对其时空分布的了解仍然很少，这阻碍了全球对比以及更好地理解它们与环境和生物变化的关系。在这些沉积物中，在纽芬兰东部的Gaskiers组和附近的Trinity二晶岩在约579 - 581 Ma的辐射测量中得到了最好的限制，尽管最近的证据表明冰川作用开始于数百万年前。在这里，我们报告了两个新的U-Pb（锆石）CA-ID-TIMS测年结果，它们分别位于塔斯马尼亚西北部的Croles Hill二晶岩单元下方和之前被解释为冰川起源的流纹石单元内：579.20±0.09 Ma和578.86±0.23 Ma。这些年龄使得Croles Hill辉长岩比Gaskiers组（>579.88±0.44 Ma）略年轻，但可以与Trinity辉长岩进行对比。所有三种晶岩的沉积都发生在一个狭窄的（2.7微米）时间窗口内。Croles Hill双晶岩的特征与冰川起源相一致，包括罕见的层状泥岩和滴石，Togari群内单一，一致的地层位置，以及碎屑成分的多样性。

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来源期刊

Precambrian Research 地学-地球科学综合

CiteScore

7.20

自引率

28.90%

发文量

325

审稿时长

12 months

期刊介绍： Precambrian Research publishes studies on all aspects of the early stages of the composition, structure and evolution of the Earth and its planetary neighbours. With a focus on process-oriented and comparative studies, it covers, but is not restricted to, subjects such as: (1) Chemical, biological, biochemical and cosmochemical evolution; the origin of life; the evolution of the oceans and atmosphere; the early fossil record; palaeobiology; (2) Geochronology and isotope and elemental geochemistry; (3) Precambrian mineral deposits; (4) Geophysical aspects of the early Earth and Precambrian terrains; (5) Nature, formation and evolution of the Precambrian lithosphere and mantle including magmatic, depositional, metamorphic and tectonic processes. In addition, the editors particularly welcome integrated process-oriented studies that involve a combination of the above fields and comparative studies that demonstrate the effect of Precambrian evolution on Phanerozoic earth system processes. Regional and localised studies of Precambrian phenomena are considered appropriate only when the detail and quality allow illustration of a wider process, or when significant gaps in basic knowledge of a particular area can be filled.