Abstract The Late Paleozoic Ice Age (LPIA) was the penultimate major glaciation of the Phanerozoic. Published compilations indicate it occurred in two main phases, one centered in the Late Carboniferous (~315 Ma) and the other in the Early Permian (~295 Ma), before waning over the rest of the Early Permian and into the Middle Permian (~290 Ma to 275 Ma), and culminating with the final demise of Alpine-style ice sheets in eastern Australia in the Late Permian (~260 to 255 Ma). Recent global climate modeling has drawn attention to silicate weathering CO2 consumption of an initially high Greater Variscan edifice residing within a static Pangea A configuration as the leading cause of reduction of atmospheric CO2 concentrations below glaciation thresholds. Here we show that the best available and least-biased paleomagnetic reference poles place the collision between Laurasia and Gondwana that produced the Greater Variscan orogen in a more dynamic position within a Pangea B configuration that had about 30% more continental area in the prime equatorial humid belt for weathering and which drifted northward into the tropical arid belt as it transformed to Pangea A by the Late Permian. The presence of widespread equatorial coal basins with Euramerica flora in the footprint of the Greater Variscan orogen during the Late Carboniferous is more compatible with a heterogeneous horst-and-graben morphology, characterized by uplifted crystalline massifs acting as loci of intense silicate weathering CO2 consumption and supplying sediment for proximal basins as venues of organic carbon burial, than a contiguous high mountain plateau, as assumed in recent climate modeling of the LPIA and its demise. The culminating phase of the LPIA occurred at about 275 Ma with the transformation from Pangea B to Pangea A and the attendant reduction of continental area in the equatorial humid belt, as well as with continued northward drift that placed what remained of the Greater Variscan orogen into the Zechstein arid belt in the Late Permian, by which time the geologic landscape was largely blanketed with siliciclastics. The resulting warming from reduced silicate weathering and thus increasing pCO2 was interrupted at 260 Ma with a cooling trend that coincided with emplacement of the Emeishan large igneous province on the equatorial South China Craton as well as the drift of the Cimmerian continental blocks through the equatorial humid belt due to opening of the Neo-Tethys. A return to ice age conditions from the increase in silicate weathering uptake of CO2 was avoided by drift of the Emeishan large igneous province out of the equatorial belt, that in conjunction with massive outgassing from emplacement of the Siberian Traps in high latitudes at the end of the Permian (252 Ma), helped steer the climate system to sustained non-glacial conditions.

中文翻译：

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Pangea B和晚古生代冰河时代

摘要 晚古生代冰河时代（LPIA）是显生宙倒数第二次大冰期。已发表的汇编表明它发生在两个主要阶段，一个集中在晚石炭世（~315 Ma），另一个在早二叠世（~295 Ma），然后在早二叠世的其余部分减弱并进入中二叠世（~ 290 Ma 至 275 Ma），并以晚二叠世（~260 至 255 Ma）澳大利亚东部阿尔卑斯式冰盖的最终消亡而告终。最近的全球气候模型引起了人们对硅酸盐风化 CO2 消耗量的关注，该建筑最初位于静态 Pangea A 配置内的大瓦里斯坎（Greater Variscan）建筑物中的 CO2 消耗是大气 CO2 浓度降低至冰川阈值以下的主要原因。在这里，我们展示了最佳可用且偏差最小的古地磁参考极将产生大瓦里斯坎造山带的劳亚大陆和冈瓦纳大陆之间的碰撞置于盘古 B 构造中更具动态的位置，该构造在主要赤道湿润地区拥有约 30% 的大陆面积。风化带，在二叠纪晚期转变为 Pangea A 时向北漂移进入热带干旱带。在晚石炭世大瓦里斯坎造山带的足迹中广泛存在的赤道煤盆地与欧美洲植物群更符合异质地堑地堑形态，其特征是隆起的结晶地块作为强烈的硅酸盐风化二氧化碳消耗和为近端盆地提供沉积物作为有机碳埋藏场所，LPIA 及其消亡的最近气候模型所假设的连续高山高原。LPIA 的最终阶段发生在大约 275 Ma，从 Pangea B 到 Pangea A 的转变以及随之而来的赤道湿润带大陆面积的减少，以及持续的向北漂移，将大瓦里斯坎造山带的剩余部分置于晚二叠世的 Zechstein 干旱带，那时地质景观大部分被硅质碎屑覆盖。由减少的硅酸盐风化和因此增加的 pCO2 导致的变暖在 260 Ma 被中断，冷却趋势与赤道华南克拉通上峨眉山大火成岩省的就位以及辛梅里亚大陆块通过赤道潮湿的漂移相吻合。由于新特提斯的开放。峨眉山大火成岩省从赤道带漂移，加上 2010 年末高纬度西伯利亚圈闭的大量放气，避免了因硅酸盐风化吸收 CO2 增加而回到冰河时代。二叠纪（252 Ma）帮助引导气候系统进入持续的非冰川条件。