Siliceous sinter is formed by biogenic and abiogenic opal deposition around hot springs and geysers. Using Structure-from-Motion photogrammetry we generated three-dimensional models of Giant and Castle Geysers from the Upper Geyser Basin of Yellowstone National Park. We use these models to calculate an approximate mass of sinter for each (~2 and ~ 5 kton, respectively) and estimate a range of plausible long-term deposition rates for Castle Geyser (470 to 940 kg·yr⁻¹). We estimate ~2% of the silica discharged from Castle Geyser is deposited as sinter in the cone and proximal terraces. We collected 15 sinter samples following the stratigraphy of each geyser from the older terrace to the younger cone and examined them using a variety of analytical methods. We find that young opaline sinter with high water content (<12 wt% from loss on ignition) contains higher concentrations of major and trace elements, notably As, Sb, Rb, Ga and Cs, relative to older dehydrated sinter. Rare earth element (REE) concentrations in sinter are 2–3 orders of magnitude higher than in the thermal water from which they are deposited. Sinter deposits are enriched in light REE, Gd and Yb when normalized to concentrations in thermal water and enriched in Eu, Tm, and Yb when normalized to the underlying rhyolite. Sinter samples with the highest REE concentrations are also enriched in organic material, implying either microbial uptake of REE, or that organic molecules are efficient ligands that form metal complexes.

硅质烧结矿由温泉和间歇泉周围的生物和非生物蛋白石沉积形成。使用来自运动的结构摄影测量，我们生成了黄石国家公园上间歇泉盆地的巨型间歇泉和城堡间歇泉的三维模型。我们使用这些模型来计算每个烧结矿的近似质量（分别为~2 和~5 kton）并估计 Castle Geyser 的一系列合理的长期沉积速率（470 至 940 kg·yr ^-1）。我们估计大约 2% 的从 Castle Geyser 排出的二氧化硅沉积为锥体和近端阶地中的烧结体。我们根据每个间歇泉从旧阶地到新锥体的地层收集了 15 个烧结样品，并使用各种分析方法对其进行了检查。我们发现，与较老的脱水烧结矿相比，具有高含水量的年轻蛋白石烧结矿（烧失量小于 12 wt%）含有更高浓度的主要和微量元素，特别是 As、Sb、Rb、Ga 和 Cs。烧结矿中的稀土元素 (REE) 浓度比沉积它们的热水中的浓度高 2-3 个数量级。当标准化为热水中的浓度时，烧结矿床富含轻稀土元素、Gd 和 Yb，而当标准化为下伏流纹岩时，则富含 Eu、Tm 和 Yb。