The response of sediment routing to climatic changes across icehouse-to-greenhouse turnovers is not well documented in Earth's pre-Cenozoic sedimentary record. Southwest Gondwana hosts one of the thickest and most laterally extensive records of Earth's penultimate icehouse, the late Paleozoic ice age. We present the first high-resolution U-Pb zircon chemical abrasion–isotope dilution–thermal ionization mass spectrometry (CA-ID-TIMS) analysis of late Paleozoic ice age deposits in the Kalahari Basin of southern Africa, which, coupled with existing CA-ID-TIMS zircon records from the Paraná and Karoo Basins, we used to refine the late Paleozoic ice age glacial history of SW Gondwana. Key findings from this work suggest that subglacial evidence in the Kalahari region is restricted to the Carboniferous (older than 300 Ma), with glacially influenced deposits culminating in this region by the earliest Permian (296 Ma). The U-Pb detrital zircon geochronologic records from the Paraná Basin of South America, which was located downstream of the Kalahari Basin in the latest Carboniferous and Permian, indicate that large-scale changes in sediment supplied to the Paraná were contemporaneous with shifts in the SW Gondwana ice record. Gondwanan deglaciation events were associated with the delivery of far-field, African-sourced sediments into the Paraná Basin. In contrast, Gondwanan glacial periods were associated with the restriction of African-sourced sediments into the basin. We interpret the influx of far-field sediments into the Paraná Basin as an expansion of the catchment area for the Paraná Basin during the deglaciation events, which occurred in the latest Carboniferous (300–299 Ma), early Permian (296 Ma), and late early Permian (<284 Ma). The coupled ice and detrital zircon records for this region of Gondwana present opportunities to investigate climate feedbacks associated with changes in freshwater and nutrient delivery to late Paleozoic ocean basins across the turnover from icehouse to greenhouse conditions.

中文翻译：

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晚石炭世和早二叠世期间高纬度冰和气候对冈瓦纳西南部沉积物供应的控制

在地球的新生代前沉积记录中，沉积物路线对从冰库到温室周转的气候变化的响应没有得到很好的记录。冈瓦纳西南部拥有地球倒数第二个冰库——晚古生代冰河时代最厚、横向最广泛的记录之一。我们首次对非洲南部喀拉哈里盆地晚古生代冰河时代沉积物进行高分辨率 U-Pb 锆石化学磨损-同位素稀释-热电离质谱 (CA-ID-TIMS) 分析，结合现有的 CA-来自巴拉那盆地和卡鲁盆地的 ID-TIMS 锆石记录，我们用来提炼西南冈瓦纳的晚古生代冰河时代冰川历史。这项工作的主要发现表明，喀拉哈里地区的冰下证据仅限于石炭纪（大于 300 Ma），受冰川影响的沉积物在最早的二叠纪（296 Ma）时在该地区达到顶峰。位于卡拉哈里盆地下游的晚石炭世和二叠纪南美洲巴拉那盆地的 U-Pb 碎屑锆石年代学记录表明，供应给巴拉那的沉积物的大规模变化与西南方向的变化同时发生冈瓦纳冰纪录。冈瓦纳冰川消融事件与来自非洲的远场沉积物输送到巴拉那盆地有关。相比之下，冈瓦纳冰川时期与非洲来源的沉积物进入盆地的限制有关。我们将远场沉积物流入巴拉那盆地解释为冰消事件期间巴拉那盆地集水区的扩大，发生于晚石炭世（300-299 Ma）、早二叠世（296 Ma）和晚早二叠世（<284 Ma）。冈瓦纳大陆这一地区的冰和碎屑锆石耦合记录提供了研究与淡水变化和营养物输送到晚古生代海洋盆地相关的气候反馈的机会，这些变化与从冰库到温室条件的转换有关。