Stratigraphic imprint of the Late Palaeozoic Ice Age in eastern Australia: a record of alternating glacial and nonglacial climate regime

Stratigraphic and sedimentological data from New South Wales and Queensland, eastern Australia, indicate that the Late Palaeozoic Ice Age comprised at least eight discrete glacial intervals (each 1–8 Ma in duration, here termed ‘glaciations’), separated by nonglacial intervals of comparable duration. These events spanned an interval from mid-Carboniferous (<em>c</em>. 327 Ma) to the early Late Permian (<em>c</em>. 260 Ma), and illustrate a pattern of increasing climatic austerity and increasingly widespread glacial ice from initial onset until an acme in the late Early Permian, followed by an opposite trend towards the final demise of glaciation in the Late Permian. The alternating glacial–nonglacial motif suggests that the Late Palaeozoic Ice Age was considerably more dynamic than previously thought. These patterns are remarkably consistent with recent interpretations of palaeofloral change, eustatic sea-level fluctuations and CO₂–climate–glaciation relationships for this interval of time. The detailed record of alternating glacial and nonglacial climate mode disclosed herein may facilitate more closely resolved evaluations of stratigraphic records elsewhere, notably in far-field, ice-distal, northern hemisphere successions.

澳大利亚东部新南威尔士州与昆士兰州的地层学与沉积学数据表明，晚古生代冰期（Late Palaeozoic Ice Age）至少包含8个独立冰期时段（单次持续1~8百万年（Ma），本文将其统称为“冰期（glaciations）”），各冰期之间由时长相当的非冰期时段分隔。这些冰期事件的发生时段为中石炭世（约3.27亿年前）至晚二叠世早期（约2.60亿年前），呈现出从冰期初始启动，至早二叠世晚期达到鼎盛期，气候严酷程度逐步加剧、冰川覆盖范围持续扩张的演化模式；随后则呈现完全相反的趋势，直至晚二叠世冰川作用最终消亡。这种冰期与非冰期交替出现的演化特征表明，晚古生代冰期的活动性远较此前认知更为显著。上述演化模式与该时段内古植物群落更替、全球海平面波动以及二氧化碳-气候-冰川作用关系的最新研究结论高度吻合。本文所披露的这套详细的冰期-非冰期气候模式交替记录，将有助于更精准地解译其他地区的地层记录，尤其是北半球远场、冰缘区的地层序列。