It is unresolved when eolian processes began to significantly affect global mean sand composition and texture through abrasion and enhanced sorting. Reports of Proterozoic eolian textures and sedimentary structures are common, in particular from 1.8 Ga on, but the Archean (4.0–2.5 Ga) geologic record possesses only seven reported eolian occurrences which generally do not manifest more than a few diagnostic features of eolian transport. We investigate in detail sandstone units within the Moodies Group (ca. 3.22 Ga) of the Barberton Greenstone Belt, South Africa, one of the oldest well-preserved terrestrial–marine sandy successions. Eight examined locations show terrestrial facies associations, high degrees of compositional and textural maturity, and large-scale foresets; however, none show convincing evidence of eolian transport but several can be excluded with confidence. In comparison to recent eolian strata, grains are generally slightly too coarse-grained, too angular, and mostly too poorly sorted. The common presence of shale laminations, granules, rare pebbles, and shale rip-up clasts demonstrates that the investigated strata were either of aqueous origin or had been formed by eolian processes but were subsequently aqueously reworked. This is vexing because the sandy-gravelly fluvial, coastal floodplain, and estuarine depositional environments of Moodies Group strata may have been hospitable to potentially powerful and long-lasting Archean eolian processes. Early Archean eolian strata may have had a limited depositional area, may have been extensively reworked, or formed under non-actualistic conditions. Thus, the significance of eolian processes on early Earth and their potential contribution to the high degree of textural and compositional maturity of Archean quartzarenites remains poorly constrained.

中文翻译：

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随波逐流了吗？在太古代风成记录的背景下重新评估古太古代穆迪群中可能的风成地层

当风成过程开始通过磨损和强化分选显着影响全球平均沙子成分和质地时，这一问题尚未得到解决。关于元古代风成岩结构和沉积结构的报道很常见，特别是从 1.8 Ga 开始，但太古宙（4.0-2.5 Ga）地质记录仅拥有 7 个报道的风成矿点，这些风成矿点通常仅表现出一些风成输送的诊断特征。我们详细研究了南非巴伯顿绿岩带穆迪群（约 3.22 Ga）内的砂岩单元，这是最古老的保存完好的陆地-海洋砂岩层序之一。八个检查地点显示出陆地相组合、高度的成分和结构成熟度以及大规模的森林覆盖；然而，没有一个显示出令人信服的风成运输证据，但有几个可以放心地排除。与近年的风成地层相比，颗粒通常粒度稍粗，棱角太大，而且大多分选太差。页岩层状、颗粒、稀有卵石和页岩剥离碎屑的常见存在表明，所研究的地层要么是水成因，要么是由风成过程形成但随后被水再加工的。这是令人烦恼的，因为穆迪群地层的砂砾石河流、沿海洪泛区和河口沉积环境可能有利于潜在强大且持久的太古代风成过程。早期太古代风成岩地层的沉积面积可能有限，可能经过广泛改造，或在非现实条件下形成。因此，风成过程对早期地球的重要性及其对太古代石英岩高度结构和成分成熟度的潜在贡献仍然很少受到限制。