Neogene glacial geology of the Prince Charles Mountains

From the abstracts of some of the referenced papers:In the Amery Oasis of the northern Prince Charles Mountains, the glaciomarine Bardin Bluffs Formation of the Pagodroma Group was deposited between the Late Pliocene (less than 3.1 Ma) and Early Pleistocene (greater than 1 Ma). The formation provides evidence of (i) a reduced East Antarctic ice sheet compared to that of the present day and (ii) a subsequent Plio-Pleistocene ice sheet expansion. The formation consists of two member. The older, basal Member 1 is about 12.5 m thick and consists of relatively ice-distal silty, sandy and sparsely fossiliferous fjordal strata. Member 1 reflects largely ice-free marine sedimentation about 250 km inland from the current Amery Ice Shelf edge. The member is restricted to the area about the north-eastern end of Pagodroma Gorge where it infills a chemically weathered erosion surface, cut in the form of a valley on the Permo-Triassic Amery Group. Weathering occurred during aerial exposure of the Amery Oasis in a warmer climate than that of today. The younger Member 2 exceeds 40 m in thickness and is made up of coarse ice proximal glaciomarine diamicts. It overlies disconformably Member 1 at Pagodroma Gorge. Elsewhere, Member 2 rests directly upon a smoothed and striated erosion surface, cut on the Amery Group, which was part of a fjord floor. This erosional surface and the facies contrast between the two members, indicates an East Antarctic Ice Sheet expansion and Lambert Glacier grounding-line advance.The Menzies Range in the southern Prince Charles Mountains, Antarctica, records at least four intervals of Cenozoic terrestrial glacigene sedimentation, and two periods of glacial erosion. The oldest Cenozoic strata, here named the Pardoe Formation, are greater than 240 m thick, and consist of variable diamicts with subordinate sandstones and minor laminated lacustrine siltstones. The Pardoe Formation overlies a rugged erosion surface cut into Precambrian basement. Two subsequent Cenozoic sequences are here named informally the Trail diamicts and the younger Amphitheatre diamicts. The latter infilled the lower regions of an extremely rugged erosion surface, many components of which still dominate the present topography. The palaeodrainage of this erosion surface is markedly discordant with that of the older erosion surface underlying the Pardoe Formation. These three depositional events and the two associated erosion surfaces record warmer climates and increased snow accumulation under conditions of temperate wet-based glaciation. During the excavation of the sub-Amphitheatre diamict erosion surface, the East Antarctic ice sheet was either absent, further inland or the height of its surface relative to the Menzies Range as considerably lower than at present. The fourth and youngest depositional episode, recorded by a veneer of boulder gravel distributed along the northern flank of the Menzies Range, is from dry-based glacier ice, and assumed to be less than 2.6 Myr.This work was also completed for ASAC project 1065 (ASAC_1065).Some explanatory notes for the excel files are:BARDIN = Bardin BluffsGLOSS. = Glossopteris GullyBAIN= Bainmedart CovePCM = Prince Charles MountainsAM = Amery (as in Amery Oasis)Sample numbers are from different positions within exposed sequences (illustrated in figures in the paper). Top and Bottom represent the 'top' and 'bottom' position in some sequences. These are also illustrated in the figures.Positions are illustrated in the manuscript Whitehead, et al (2004).Dm = diamict sample, Mud = Mud.Raw slides = standard strewn microscope slidesConcentrated slides = heavy liquid separation to concentrate the fossilsThe fields in this dataset are:LocationNameNumberLithologyBardin BluffsBattye GlacierFisher BenchMt JohnstonLength (micrometres)Width (micrometres)引自部分参考文献的摘要内容： 在查尔斯王子山脉北部的阿梅里绿洲（Amery Oasis），帕戈德罗玛群（Pagodroma Group）的冰海相（glaciomarine）巴丁断崖组（Bardin Bluffs Formation）沉积于晚上新世（距今<3.1 Ma）至早更新世（距今>1 Ma）之间。该地层提供了两项关键证据：其一，东南极冰盖（East Antarctic Ice Sheet）规模较现今有所缩减；其二，随后发生了上新世-更新世时期的冰盖扩张。 该地层包含两个岩性段。其中较古老的基底岩性段1（Member 1）厚度约12.5 m，由相对远冰的粉砂质、砂质且化石稀少的峡湾相地层构成。岩性段1主要反映了距现今阿梅里冰架前缘约250 km的内陆无冰海洋沉积环境。该岩性段仅分布于帕戈德罗玛峡谷（Pagodroma Gorge）东北端附近区域，充填于二叠-三叠系阿梅里群（Permo-Triassic Amery Group）中被侵蚀形成的河谷状化学风化侵蚀面之上。风化作用形成于阿梅里绿洲处于大气暴露时期，彼时气候较现今更为温暖。 较年轻的岩性段2（Member 2）厚度超过40 m，由近冰的粗粒冰海相杂砾岩（diamicts）构成。在帕戈德罗玛峡谷处，该岩性段以不整合关系覆于岩性段1之上。在其他区域，岩性段2直接覆于阿梅里群上经磨蚀并带有擦痕的侵蚀面之上，该侵蚀面曾为峡湾底床的一部分。该侵蚀面以及两段岩性之间的相序差异，表明东南极冰盖发生扩张，兰伯特冰川（Lambert Glacier）的冰架接地前缘发生推进。 南极洲查尔斯王子山脉南部的曼齐斯岭（Menzies Range）记录了至少四期新生代陆相冰成沉积事件，以及两期冰川侵蚀作用。其中最古老的新生代地层被命名为帕多伊组（Pardoe Formation），厚度超过240 m，由成分复杂的杂砾岩、次要砂岩及少量纹层状湖相粉砂岩组成。帕多伊组覆于切割前寒武纪基底形成的崎岖侵蚀面之上。后续的两期新生代沉积序列被本文非正式命名为特雷尔杂砾岩（Trail diamicts）与更年轻的安菲瑟特杂砾岩（Amphitheatre diamicts）。安菲瑟特杂砾岩充填于一处极度崎岖的侵蚀面的低洼区域，该侵蚀面的多数地貌特征仍塑造了现今的地形格局。该侵蚀面的古水系与帕多伊组之下的古老侵蚀面的古水系存在显著不一致性。这三期沉积事件与伴生的两处侵蚀面，记录了在温带湿基冰川作用背景下，气候更为温暖且积雪补给量增加的时期。在侵蚀面之下的安菲瑟特杂砾岩沉积时期，东南极冰盖要么完全消失，要么退缩至更靠内陆的区域，或是其冰面相对于曼齐斯岭的高度远低于现今水平。第四期也是最年轻的沉积事件表现为沿曼齐斯岭北翼分布的砾石盖层，其形成于干基冰川环境中，年代被认为距今小于2.6 Myr。 本研究同时隶属于ASAC项目1065（ASAC_1065）。 本数据集附带的Excel文件说明如下： BARDIN = 巴丁断崖（Bardin Bluffs） GLOSS. = 舌羊齿谷（Glossopteris Gully） BAIN= 贝恩梅达特湾（Bainmedart Cove） PCM = 查尔斯王子山脉（Prince Charles Mountains） AM = 阿梅里（如阿梅里绿洲） 样品编号对应裸露沉积序列中的不同采样位置（详见论文附图）。部分序列中的Top与Bottom分别代表序列的顶部与底部位置，相关位置也在论文附图中予以标注。 采样位置的标注详见Whitehead等（2004）的研究手稿。 Dm = 杂砾岩样品，Mud = 泥质样品。 Raw slides = 标准涂布显微镜载片 Concentrated slides = 经重液分选富集化石的载片 本数据集包含以下字段：采样位置（Location）、样品名称（Name）、样品编号（Number）、岩性（Lithology）、巴丁断崖（Bardin Bluffs）、巴蒂耶冰川（Battye Glacier）、费希尔阶地（Fisher Bench）、约翰斯顿山（Mount Johnston）、长度（微米）、宽度（微米）。