We provide a test for recent arguments that the West Antarctic Ice Sheet (WAIS) is underlain by an extensive outcrop of volcanic rock (mainly basalt) by examining the non-clay and clay mineral composition of sediments collected in front of and under the Ross Ice Shelf. If the proposed large volume were present, then we posit that glacial erosion and transport would deliver sediments to the Ross Sea enriched in minerals diagnostic of alkaline basalt, namely olivine, pyroxene, and plagioclase, and no quartz. Using quantitative X-ray diffraction analysis, we determine the weight percent of minerals in West Antarctic alkaline basalt, dolerite, gneiss, and granite bedrock, and compare these with a suite of 49 surface and near-surface sediment samples from a 1400 km west to east transect across the Ross Sea. Fifty percent of the samples had quartz percentage values >25% and had very small wt percentages of diagnostic basalt minerals. A sediment unmixing algorithm, with basalt, dolerite, gneiss and granite bedrock, end members, showed that the sediment contained virtually no basalt, was dominated by granite compositions, but did show some samples with an admixture of material derived from the Ferrar dolerite, which crops out extensively in the Transantarctic Mountains. Indicators of possible late Cenozoic volcanic bedrock – pyroxene, forsterite, and smectite weight percentages – decrease from west to east across the Ross Sea opposite to the trend of the quartz weight percent. Our study provides no support for the presence of extensive basalt outcrop under the WAIS, hence indicates that any changes in ice stream stability will not be influenced by basal heat regime.

我们通过检查在罗斯冰之前和之下收集的沉积物的非粘土和粘土矿物成分，为最近关于南极西部冰盖 (WAIS) 下伏有大量火山岩（主要是玄武岩）的论点提供了检验架子。如果提议的大体积存在，那么我们假设冰川侵蚀和运输会将沉积物输送到罗斯海，其中富含碱性玄武岩的矿物诊断，即橄榄石、辉石和斜长石，而没有石英。使用定量 X 射线衍射分析，我们确定了南极西部碱性玄武岩、辉绿岩、片麻岩和花岗岩基岩中矿物质的重量百分比，并将这些与来自西部 1400 公里的 49 个地表和近地表沉积物样品进行比较。东横断罗斯海。50% 的样品的石英百分比值 >25%，诊断玄武岩矿物的重量百分比非常小。具有玄武岩、辉绿岩、片麻岩和花岗岩基岩，端部成员的沉积物分离算法表明，沉积物几乎不含玄武岩，主要是花岗岩成分，但确实显示了一些样品与源自费拉辉绿岩的材料的混合物，后者在横贯南极山脉广泛种植。可能的晚新生代火山基岩的指标——辉石、镁橄榄石和蒙脱石的重量百分比——穿过罗斯海从西向东下降，与石英重量百分比的趋势相反。我们的研究不支持在 WAIS 下存在大量玄武岩露头，