The Great Unconformity at the Precambrian-Cambrian boundary marks a global erosion surface, and a time gap which in places exceeded a billion years. The weathered sub-Cambrian rocks include abundant granites and pegmatites. These rocks and others were mineralized in several regions. The basal Cambrian sediments show that rare commodities including gold and rare earth elements (REEs) were concentrated from sub-Cambrian sources by both chemical and physical processes. The clay-rich unconformity in Europe demonstrates the weathering of Palaeoproterozoic pegmatites (∼1.2 billion years older) and liberation of strontium and REEs to reprecipitate as authigenic phosphate minerals. This is consistent with a global strontium isotope excursion at the Precambrian-Cambrian boundary. The global extent of sub-Cambrian granites and pegmatites indicates a possible exploration play for REEs. More generally, the abundance of ores exposed on the surface globally, and examples of early Cambrian enrichment, indicate that the surface has high potential for exploration of rare elements.

中文翻译：

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前寒武纪-寒武纪边界稀土元素的循环

前寒武纪-寒武纪边界的大不整合面标志着全球侵蚀面，以及一些地方超过十亿年的时间差距。风化的亚寒武纪岩石包括丰富的花岗岩和伟晶岩。这些岩石和其他岩石在几个地区被矿化。寒武纪基底沉积物表明，包括金和稀土元素（REE）在内的稀有商品是通过化学和物理过程从亚寒武纪来源浓缩的。欧洲富含粘土的不整合面展示了古元古代伟晶岩（约 12 亿年前）的风化以及锶和稀土元素的释放，以自生磷酸盐矿物的形式重新沉淀。这与前寒武纪-寒武纪边界的全球锶同位素偏移一致。全球范围内的亚寒武统花岗岩和伟晶岩表明了稀土元素可能的勘探前景。更一般地说，全球地表暴露的丰富矿石以及早寒武纪富集的例子表明，地表具有勘探稀有元素的巨大潜力。