Abstract Pleistocene (bedded) travertines from Acquasanta Terme display ranges of Sr and (REE + Y) contents (462–1576 mg/kg and 250–13,789 ng/g, respectively), which are consistent with an evaporitic rock source. PAAS-normalized (REE + Y) patterns may support the origin of travertine-bearing fluids from marine rocks. Travertines exhibit a very narrow range of δ87Sr values (from −1.9 to −1.84 or 87Sr/86Sr ratios from 0.70782 ± 6 to 0.70786 ± 6), indicating an unchanged rock source throughout the travertine depositional time (from about >350 to 26 ka), likely represented by Burano evaporites (Upper Triassic), as suggested by previous authors. No Sr contribution from magmatic sources has been detected. Travertines also display a very narrow range of ϵNd values (from -9.1 to −7.8 or 143Nd/144Nd ratios from 0.51217 to 0.51224), indicating an unchanged source also for (REE + Y) through time, likely the same one providing Sr. Lastly, chemical and isotopic data of Acquasanta travertines have been compared with those of bedded travertines from Semproniano (Tuscany) of similar age. In particular, δ87Sr values clearly distinguish between the two groups, in agreement with their different rock sources. As a whole, these new geochemical and isotopic data on Acquasanta travertines have provided a deeper insight into the origin of their parent hydrothermal fluids, which, upwelling from significant depth, circulated through an area still affected by major seismic activity. In particular, the application of Nd isotopes has resulted useful, as, unlike Sr isotopes of fluid which tend to re-equilibrate rather quickly with rocks along upwelling pathways, Nd isotopes sluggishly do so, thus better reflecting the fluid source.

中文翻译：

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评估来自 Acquasanta Terme 地区（意大利中部马尔凯）中上更新世石灰华中 Sr 和 Nd 同位素和 (REE+Y) 的起源及其对新构造的影响

摘要 来自 Acquasanta Terme 的更新世（层状）石灰华显示 Sr 和（REE + Y）含量范围（分别为 462–1576 mg/kg 和 250–13,789 ng/g），这与蒸发岩源一致。PAAS 归一化 (REE + Y) 模式可能支持来自海相岩石的含钙华流体的起源。石灰华的 δ87Sr 值范围非常窄（从 -1.9 到 -1.84 或 87Sr/86Sr 比率从 0.70782 ± 6 到 0.70786 ± 6），表明在整个钙华沉积时间（从大约 >350 到 26 ka），岩石源没有变化，很可能以布拉诺蒸发岩（上三叠纪）为代表，正如以前的作者所建议的那样。没有检测到来自岩浆源的 Sr 贡献。石灰华还显示出非常窄的 ϵNd 值范围（从 -9.1 到 -7.8 或 143Nd/144Nd 比率从 0.51217 到 0.51224），表明 (REE + Y) 的来源也随时间保持不变，可能与提供 Sr 的来源相同。最后，将 Acquasanta 石灰华的化学和同位素数据与来自 Semproniano（托斯卡纳）的类似年龄的层状石灰华的化学和同位素数据进行了比较。特别是，δ87Sr 值清楚地区分了两组，与它们不同的岩石来源一致。总的来说，这些关于 Acquasanta 石灰华的新地球化学和同位素数据提供了对其母热液起源的更深入的了解，这些热液从很深的深度向上涌出，流经仍受重大地震活动影响的地区。特别是，Nd 同位素的应用产生了有用的结果，因为与流体的 Sr 同位素不同，它们往往会很快与上升流通道的岩石重新平衡，而 Nd 同位素则缓慢地这样做，