Caves in tropical regions form a key resource for those reconstructing human evolution and dispersals. However, the complex sedimentary records they contain remain under-interpreted because of the poorly constrained effects of humid tropical climates upon archaeological site formation processes. Guano-driven phosphatic diagenesis impacts archaeological preservation in caves, but atypical features observed in guano layers in prominent Southeast Asian archaeological sites suggested that hot and humid conditions had promoted the formation of distinctive sedimentary environments with unknown effects on assemblage taphonomy. Few reference data exist that are relevant to geomorphic processes in tropical caves and this laboratory-based modern analogue study was designed to conclusively relate analytical observations to sedimentary palaeoenvironments and explore their effects on assemblage taphonomy. Stratigraphic models were kept under simulated tropical conditions, each containing an identical range of faunal remains, organic materials and mineralss, which was buried in wet bat guano. These were excavated, one per month over 24 months, while nine further stratigraphic models were used to control for environmental variables. Sedimentary environments were investigated using sedimentological characterisations of excavated sediments, while post-depositional alterations to buried materials were investigated through optical and scanning electron microscopic analysis of thin-section samples combined with chemical characterisations of excavated samples through Fourier-transform infrared spectroscopy (FTIR). Experimental conditions prevented the sediment acidification that is typically associated with guano-driven diagenesis, but buried materials were severely, and distinctively, diagenetically altered. Organic decomposition in guano, bamboo and charcoal was associated with the activities of sulphate-reducing bacteria, but diagenetic alterations affecting charcoal remain poorly resolved due to variation in the experimental assemblage. Bone was discoloured and affected by dissolution, recrystallisation and alteration to secondary minerals, including gypsum, while carbonates reprecipitated as calcium phosphates and non-stochiometric mineral species. Diagenesis of clay minerals was observed, but related diagenetic trajectories remain poorly resolved. These alterations provide micromorphological and mineralogical indicators of sedimentary palaeoenvironments in the earliest stages of burial and this experiment provides a framework within which to understand the taphonomy of archaeological materials in tropical caves.

热带地区的洞穴是重建人类进化和传播的重要资源。然而，由于潮湿的热带气候对考古遗址形成过程的制约作用很弱，因此它们所包含的复杂沉积记录仍未得到很好的解释。鸟粪驱动的磷酸盐成岩作用影响洞穴的考古保存，但是在东南亚著名考古遗址的鸟粪层中观察到的非典型特征表明，炎热和潮湿的条件促进了独特的沉积环境的形成，而对组合拓扑学的影响未知。很少有参考数据与热带洞穴中的地貌过程有关，而这种基于实验室的现代模拟研究旨在将分析性观测结果与沉积古环境最终联系起来，并探讨它们对组合形态学的影响。地层模型保持在模拟的热带条件下，每个模型都包含相同范围的动物遗骸，有机材料和矿物质，它们被埋在湿蝙蝠鸟粪中。这些被挖掘出来，在24个月中每月一次，而另外九个地层模型被用来控制环境变量。使用挖掘出的沉积物的沉积学特征研究了沉积环境，同时通过光学和扫描电子显微镜对薄片样品进行显微分析，并结合通过傅立叶变换红外光谱（FTIR）对挖掘出的样品进行化学表征，研究了对沉积材料的沉积后蚀变。实验条件阻止了通常与鸟粪驱动的成岩作用有关的沉积物酸化，但掩埋的材料却发生了严重的，明显的，非正电的改变。鸟粪，竹子和木炭中的有机分解与硫酸盐还原菌的活性有关，但是由于实验组合的变化，影响木炭的成岩作用改变仍然难以解决。骨变色并受溶解，重结晶和对次生矿物（包括石膏）的改变的影响，而碳酸盐会重新沉淀为磷酸钙和非化学计量的矿物质。观察到粘土矿物的成岩作用，但相关的成岩轨迹仍然难以解决。这些变化为埋葬的早期阶段的沉积古环境提供了微观形态和矿物学指示，该实验为了解热带洞穴中考古材料的分类提供了一个框架。