Detrital zircon provenance of Permo-Carboniferous glacial diamictites across Gondwana
Detrital zircon provenance of Permo-Carboniferous glacial diamictites across Gondwana
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DOI：
10.1016/j.earscirev.2019.01.014
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发表时间：
2019-05
影响因子：
12.1
通讯作者：
J. Craddock;R. W. Ojakangas;D. Malone;A. Konstantinou;A. Mory;W. Bauer;R. Thomas;S. C. Affinati;K. Pauls;Udo Zimmerman;G. Botha;Anthony Rochas-Campos;P. R. Santos;E. Tohver;C. Riccomini;Joe R Martin;J. Redfern;M. Horstwood;G. Gehrels
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文献类型：
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作者：
J. Craddock;R. W. Ojakangas;D. Malone;A. Konstantinou;A. Mory;W. Bauer;R. Thomas;S. C. Affinati;K. Pauls;Udo Zimmerman;G. Botha;Anthony Rochas-Campos;P. R. Santos;E. Tohver;C. Riccomini;Joe R Martin;J. Redfern;M. Horstwood;G. Gehrels
冈瓦纳在晚古生代（338-265 Ma）相对于南极改变了其高纬度位置，冰川样式从局部高山冰川和冰原演变为遍布超大陆的约30个小冰原。本文报道了来自非洲（5个）、南极洲（5个）、澳大利亚（8个）、埃尔斯沃斯山脉（1个）、福克兰群岛（2个）、印度（1个）、马达加斯加（1个）、阿曼（3个）、赤道拉萨地体（2个）、赤道北钱棠地体（2个）和南美洲（10个）冈瓦纳辉长岩矿床的重矿物种群（n= 2217）和碎屑锆石年龄（n= 2920 U-Pb LA-ICPMS结果）。重矿物分离（SEM-WDS分析）发现了一个异常，只有在Dwyka群和Dwyka等效样品中才有榴石，这表明它是一个超镁质南极来源。碎屑锆石年龄分布的统计分析支持了来自许多小冰中心的沉积物局部输运的推断，其中有5个远场冰输运的例子（>1000 km； 4个冰流的例子>2000 km）和3个来自南极洲沿海冰原的例子。我们认为冰分布于冈瓦纳南部的5个不同时代的主要冰盖，冰从冈瓦纳中部流出。我们还证实了北美洲（风成和河流）和冈瓦纳（火山灰，碎屑-冰川）的二叠纪-石炭世碎屑锆石种群没有在赤道或海道上混合，并考虑了晚古生代雪球地球的可能性。
Gondwana changed its high latitude location during the late Paleozoic (338–265 Ma), relative to the South Pole, and the style of glaciation evolved from localized alpine glaciers and ice fields to ~30 small ice sheets across the supercontinent. We report the analysis of heavy mineral populations (n= 2217) and the ages of detrital zircons (n= 2920 U-Pb LA-ICPMS results) from Gondwana diamictite deposits from eight landmasses: Africa (5 samples), Antarctica (5), Australia (8), the Ellsworth Mountains terrane (1, Antarctica), the Falkland Islands (2, diamictite plus U-Pb SHRIMP ages on granite clasts), India (1), Madagascar (1), Oman (3), the equatorial Lhasa terrane (2), the equatorial North Qiantang terrane (2) and South America (10). Heavy mineral separations (SEM-WDS analysis) identified one anomaly, pyrope garnets present only in Dwyka Group and Dwyka-equivalent samples suggesting an ultramafic Antarctic source. Statistical analysis of detrital zircon age distributions support the inference of local transport of sediment from many small ice centers with five examples of far-field ice transport (>1000 km; four with ice flow >2000 km), and three from ice fields located along coastal Antarctica. We propose that ice was distributed from five main ice-caps of different ages in southern Gondwana with ice flow away from central Gondwana. We also confirm that the Permo-Carboniferous detrital zircon populations of Euramerica (eolian and fluvial) and Gondwana (ash, detrital-glacial) are not mixed across the equator or seaway and ponder the possibility of a late Paleozoic snowball Earth.