Speleothems form layered archives of the climate and local cave conditions during their formation. The origin of layering in cave pearls, however, is not well-understood. Cave pearls grown in two adjacent mine sites between 2006 and 2014 elucidate the complexity of speleothem growth and recrystallization. Site A cave pearls grew under an active drip, while Site B cave pearls grew in small rimstone-dam pools that filled with reverse-graded fitted pearls between about 2009 and 2014. Despite the variation in pool setting, all samples are layered in grey and/or brown laminations and dendrites. The order and number of these layers varies widely, even between pearls growing millimetres apart in the same pool. However, stable isotope values reflect homogenized local precipitation. The variability between adjacent samples supports control by very local factors within each pool, likely related to CO₂ degassing at the water–air interface and water flow within the confined space of each pool. Recrystallization of calcite to calcite occurs resulting in triangular microspar patches and much less obvious bladed calcite. Laminations of brown or grey 1 to 5 µm calcite crystals recrystallize to bladed calcite up 100 µm long, all the while retaining a memory of the original layers in the form of ‘ghost’ layers, as revealed by gentle acid etching. Pearls at the top of rimstone-dam pools grew faster than those just a few millimetres deeper, resulting in reverse grading. This model is applicable to reverse grading in marine and lacustrine pisolites. This study suggests that cave pearls in active flow regimes (drips or currents) are similar and largely abiogenic, in contrast to other locations with less flow, where more biological input is common. Recrystallization of calcite to calcite proceeds not only to equant spar (classic Ostwald ripening), but also to bladed calcite. Thus, bladed calcite in speleothems needs to be carefully evaluated for recrystallization even when aragonite is absent.

中文翻译：

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洞穴珍珠池的兴衰：一个珍珠矿场的高度可变的生长、再结晶和消亡

Speleothems 在形成过程中形成了气候和当地洞穴条件的分层档案。然而，洞穴珍珠中分层的起源尚不清楚。2006 年至 2014 年间在两个相邻矿场生长的洞穴珍珠阐明了洞穴珍珠生长和再结晶的复杂性。大约在 2009 年至 2014 年间，A 站点的洞穴珍珠在活跃的滴水下生长，而 B 站点的洞穴珍珠则生长在充满反向分级适合珍珠的小型边缘石坝池中。尽管池设置有所不同，但所有样品都以灰色和灰色分层。 /或棕色叠片和枝晶。这些层的顺序和数量差异很大，即使在同一池中相距数毫米的珍珠之间也是如此。然而，稳定的同位素值反映了均匀的局部降水。₂在水-空气界面脱气，水在每个水池的密闭空间内流动。方解石重结晶为方解石，导致三角形微晶石斑块和不太明显的带刃方解石。棕色或灰色 1 至 5 µm 方解石晶体的叠层重结晶为长达 100 µm 的带刃方解石，同时通过温和的酸蚀刻显示出“幽灵”层形式的原始层的记忆。边缘石坝池顶部的珍珠比深度仅几毫米的珍珠生长得更快，导致反向分级。该模型适用于海相和湖相海相岩的反向分级。这项研究表明，活跃流动状态（滴水或水流）中的洞穴珍珠与其他流动较少的地方（通常有更多的生物输入）相似，并且主要是非生物来源的。方解石重结晶为方解石的过程不仅会导致等长晶石（经典的 Ostwald 熟化），还会导致带叶片的方解石。因此，即使没有文石，也需要仔细评估洞穴中的带刃方解石的再结晶。