Eolian Dispersal Patterns of Zircon and its Subsurface Geochemistry in Continental Weathering Systems

大陆风化系统中锆石的风成扩散模式及其地下地球化学

• 批准号: 9220049
• 负责人: George Brimhall
• 金额: $ 21.08万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-02-15 至 1996-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9220049&HistoricalAwards=false
• 关键词: Eolian; Dispersal; Patterns; Zircon; its

Having confirmed the eclectic nature and presence of eolian additions in a classical lateritic regolith in Australia, we request renewal of this funding for continued study off continental weathering systems. We seek to make more new applications of unique microbeam capabilities of the SHRIMP (sensitive high-resolution ion microprobe) to surface process studies centering on the provenance, surficial transport and in situ weathering behavior of zircon, a chemically resistant and datable pathfinder mineral of unparalleled utility. We wish to define ancient eolian dispersal patterns and mineralogical gradients of dust-size weathering product and insoluble detrital accessory minerals across the tectonically-stable Yilgarn craton of Western Australia. Our study will focus on sampling a sequence of uneroded laterites in an easterly transect leading away from the principal source region which we infer to have contributed foreign zircon to the Jarrahdale bauxite near Perth Australia by paleo-eolian processes. In the 700 Ma Leeuwin Block of the Pinjarra Orogen source region, we wish to study the accessory mineral suite (zircon, rutile, monazite and ilmenite) in bedrock granite, granulite and anorthosite exposures and date the zircons. Also, by dating eolian zircons in contemporary dust samples collected from rain gauge arrays, we can ascertain if source regions have shifted significantly. Finally, we wish to study the mineralogical and isotopic processes of in situ weathering of parent material zircon and to pursue direct SHRIMP dating of authigenic anatase. We wish to test their use in characterizing and timing the advance of the weathering front and biomechanical admixing rate of detritus into the subsurface thereby augmenting the array of geochronological methods available for surficial process studies.

在确认了折衷的性质和存在的 在典型的红土风化层中的风成附加物 澳大利亚，我们要求延长这一资金， 研究大陆风化系统。 我们力求使 独特的微束功能的更多新应用 SHRIMP（灵敏高分辨率离子微探针）， 以物源为中心的地表过程研究， 表层土运移和原位风化行为 锆石，一种化学抗性和可测年代的开拓者 具有无与伦比的用途的矿物。 我们希望定义古代 风成分散模式和矿物学梯度 粉尘级风化产物和不溶性碎屑 在构造稳定的Yilgarn的副矿物 西澳大利亚的克拉通。 我们的研究将集中在 在东风中采集一系列未被侵蚀的红土 远离主要源区的样带， 我们推断， 澳大利亚珀斯附近的贾拉代尔铝土矿 流程. 在平贾拉的700 Ma Leeuwin街区 造山带源区，我们希望研究副矿物 基岩中的锆石、金红石、独居石和钛铁矿 花岗岩、麻粒岩和斜长岩暴露， 锆石 此外，通过对当代风成锆石的年代测定， 从雨量计阵列收集的灰尘样本，我们可以 确定源区是否发生了重大变化。 最后，我们希望研究矿物学和同位素 母质锆石原地风化过程 对自生铀进行直接SHRIMP测年。 我们希望测试它们在表征和计时 风化前缘的进展与生物力学混合 碎屑进入地下的速度，从而增加了 一系列地质年代学方法可用于地表测量 过程研究。