Provenance, Age and Biomechanics of SuperContinental Weathering

有一些内在的性质统一在 他们在冈瓦纳大陆的分散位置 深层暴露 这个超大陆的地壳水平是一个重要的前兆 大陆风化作用对于 大陆风化过程本身。 这些人 属性包括：岩石学和矿物学特征 它独特的热历史 水和产热元素的消耗、隆起、侵蚀 和最终的稳定性， 当受到强烈的风化作用时的构造静止。 这 陆壳深部横贯大陆带， 麻粒岩-紫苏花岗岩-斜长岩体平行于冈瓦纳纪 古生代和早中生代板块汇聚造山带 影响南美洲、非洲、印度、澳大利亚和南极洲 暗示冈瓦纳超大陆规模的风化作用 适当的地壳分析单位，而不是单个 大陆块 查看红土的必要性 超大陆尺度的风化作用进一步加剧， 事实上，红土的经典“残余”起源 铝土矿与最近发现的 由三水铝石、赤铁矿和针铁矿组成的外来粉尘也 含有一种抗碎屑矿物成分， 其他地方的基底岩石（锆石、钛铁矿、金红石和独居石） 控制铝土矿的近表面金属富集， 红土 通过考虑地壳运动 大陆风化作用以及表层再循环， 耐化学性矿物的重新分布， 深部岩石学和矿物学的直接结果 地壳，我们制定了一个可测试的模型，深地壳 风化系统 计划实施一个由三部分组成的综合项目 解决（1）化学稳定碎屑的来源 矿物，特别是锆石污染的上部 红土风化的年龄和持续时间 结合古风化面对比， 澳大利亚、西非和巴西，以及（3） 地表下的搬运和碎屑进入 膨胀生物力学混合过程中的红土风化层 根生长周期的风成尘。 第一部分利用U-Pb离子 用SHRIMP微探针测定锆石年龄， 移动的矿物来源及其迁移深度 红土和铝土风化剖面。 第二部分涉及 黄钾铁矾及锰、铁的~（40）Ar/~（39）Ar激光定年 氧化物 第三部分是使用土壤的实验室实验 模拟根系生长周期的力学细胞。 的 跨学科的研究有助于进一步 发展一个急需的长期大陆记录， 补充海洋地层学 全球进程的记录。

There are a number of intrinsic properties of cratons unified in their pre-dispersal position in Gondwana. Exposure of deep crustal levels of this supercontinent is an essential precursor to continental weathering being vital to the on set and nature of the continental weathering process itself. These cratonal attributes include: the petrological and imeralogical character of the bedrock parent material, its unique thermal history, depletion in water and heat-producing elements, uplift, erosion and ultimate stability necessary for attainment of a state of tectonic quiescence when subjected to intense weathering. This transcontinental belt of deep continental crust exposed as graulite-charnockite-anorthosite bodies parallels the Gondwanide Orogen of Paleozoic and Early Mesozoic plate convergence affecting South America, Africa, India, Australia and Antarctica implicating Gondwana supercontinental scale weathering as the appropriate crustal unit of analysis rather than individual continental land masses. The necessity of viewing lateritic weathering on a supercontinental scale is further accentuated by the fact that the classical "residual" origin of lateritic bauxites is inconsistent with a recent discovery that wind-blown foreign dust consisting of gibbsite, hematite and goethite also bearing a component of resistant detrital minerals derived from basement rocks elsewhere (zircon, ilmenite, rutile and monazite) dominates near surface metal enrichment of bauxites and laterites. By considering the crustal processes preceding continental weathering as well as the surficial recycling and redistribution of chemically-resistant minerals accessed as a direct consequence of the petrology and mineralogy of the deep crust, we have formulated a testable model of deep crustal weathering systems. An integrated three-part project is planned addressing (1) the provenance of chemically-stable detrital minerals, especially zircon contaminating the upper portions of laterites, (2) age and duration of lateritic weathering in combination with correlations of paleo-weathering surfaces in Australia, West Africa and Brazil, and (3) mechanisms of subsurface transport and incorporation of detritus into the lateritic regolith during dilational biomechanical mixing of eolian dust by root growth cycles. Part I utilizes U-Pb ion microprobe dating of zircon using the SHRIMP to define the sources of mobile minerals and the depths of their translocation into laterite and bauxite weathering profiles. Part II involves 40Ar/39Ar laser dating of jarosite as well as manganese and iron oxides. Part III is laboratory experimentation using a soil mechanics cell capable of simulation root growth cycles. The proposed interdisciplinary research can contribute to further development of a much-needed long-term continental record of surficial environments to complement the marine stratigraphic record of global processes.