Increasing evidence suggests that supergene exotic copper deposits were emplaced during periods of geomorphic quiescence and pulses of humidity in arid environments. We tested this idea in the Centinela Mining District in the Atacama Desert (northern Chile). We collected 14 sand samples at depth (up to 110 m) in two open-pit mines (Central Tesoro and Mirador) exposing Miocene sediment, and located in the El Tesoro Basin, which hosts two exotic copper-rich orebodies. We inverted the ¹⁰Be and ²¹Ne concentrations by using a two-box model (IMIS, inversion of multi-isotopes in a sedimentary basin) composed of an eroding source of sediment and a depositional sedimentary basin, and by selecting denudation and sedimentation rate histories that can explain our data. The ages found demonstrate that the two exotic orebodies were deposited during a narrow period between 14 Ma (10 Ma younger than previously thought) and 9.5 Ma, when an ignimbrite covered the sedimentary sequence. The dated lower exotic copper orebody was deposited during or just before a sharp decrease in the sedimentation rates (from >100 to 0.5–5 m/Ma), which is consistent with published sedimentological and carbonate isotopic data in this district. This confirms the idea that exotic deposits form during a quiescence of the geomorphic activity. Nevertheless, our model suggests that the back-ground denudation rate providing sediment to these basins between ca. 14 Ma and ca. 9.5 Ma was surprisingly high (>250 m/Ma) for such an arid environment. These denudation rates can be explained by a relatively rapid local back-scarp retreat providing most of the sediment to these basins and possibly a wetter climate compared to the present. Then, during the period 10–7 Ma, the denudation rates decreased to >50 m/Ma. This decrease may correspond to a local progressive decrease in the slope of the surrounding hills, or to a progressive aridification, or a combination of both phenomena.

中文翻译：

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智利阿塔卡马宇宙成因核素（10Be 和 21Ne）的新近系盆地充填：对古气候和表生铜矿化的影响

越来越多的证据表明，在干旱环境中地貌静止和湿度脉冲期间，表生外来铜矿床就位。我们在阿塔卡马沙漠（智利北部）的 Centinela 矿区测试了这个想法。我们在两个暴露中新世沉积物的露天矿（Central Tesoro 和 Mirador）收集了 14 个深度（最深 110 m）的沙子样本，这些矿井位于 El Tesoro 盆地，该盆地拥有两个奇异的富铜矿体。我们颠倒了¹⁰ Be 和²¹通过使用由沉积物侵蚀源和沉积沉积盆地组成的双箱模型（IMIS，沉积盆地中的多同位素反演），并通过选择可以解释我们的数据的剥蚀和沉积速率历史来计算 Ne 浓度。发现的年龄表明，这两个奇异的矿体是在 14 Ma（比以前认为的年轻 10 Ma）和 9.5 Ma 之间的一个狭窄时期内沉积的，当时沉积岩覆盖了沉积层序。在沉积速率急剧下降（从 >100 到 0.5-5 m/Ma）期间或之前沉积了年代较低的奇异铜矿体，这与该地区已发表的沉积学和碳酸盐同位素数据一致。这证实了在地貌活动静止期间形成外来沉积物的想法。尽管如此，我们的模型表明，背景剥蚀速率为这些盆地之间提供了沉积物。14 马和约。对于这样一个干旱的环境，9.5 Ma 是惊人的高 (>250 m/Ma)。这些剥蚀率可以通过相对较快的局部后陡坡后退向这些盆地提供大部分沉积物以及可能比现在更潮湿的气候来解释。然后，在 10-7 Ma 期间，剥蚀率下降到 >50 m/Ma。这种下降可能对应于周围山坡坡度的局部逐渐减小，或对应于逐渐干旱化，或这两种现象的组合。这些剥蚀率可以通过相对较快的局部后陡坡后退向这些盆地提供大部分沉积物以及可能比现在更潮湿的气候来解释。然后，在 10-7 Ma 期间，剥蚀率下降到 >50 m/Ma。这种下降可能对应于周围山坡坡度的局部逐渐减小，或对应于逐渐干旱化，或这两种现象的组合。这些剥蚀率可以通过相对较快的局部后陡坡后退向这些盆地提供大部分沉积物以及可能比现在更潮湿的气候来解释。然后，在 10-7 Ma 期间，剥蚀率下降到 >50 m/Ma。这种下降可能对应于周围山坡坡度的局部逐渐减小，或对应于逐渐干旱化，或这两种现象的组合。