Artisanal and small-scale gold mining (ASGM) flourishes along many tropical rivers, and it still requires proper documentation in many countries, as well as interpretation in terms of rational resource exploitation and wildlife preservation. In this study we used remote sensing techniques to analyze two representative examples of ASGM: one along the Marupa River in Brazil (Tapajós Domain) and another one along the Kahayan River in Indonesia (Central Kalimantan). The documented spatial extent of ASGM is ~9175 km2 along the Marupa River and ~30,427 km2 along the Kahayan River. It was established these activities change rapidly (2-3 years) in space. Although active and inactive sites occur in both areas, a great number of inactive sites distinguish the Marupa River. It is very crucial that ASGM along the Marupa and Kahayan rivers link strongly to watercourse meanders, but also changes river valley morphology. This is an interesting evidence of coupled fluvial-anthropic morphodynamics of meandering river valleys. Geological phenomena represented in the study areas include gold resource exploitation (economic phenomenon), landforms and their dynamics (geomorphological phenomenon), and mercury environmental pollution (geochemical phenomenon). Due to remarkable spatial extent and evident interconnection, these phenomena seem to be unique and, thus, constituting geological heritage. Identification of the latter means that ASGM sites add value to the local environment. A paradox is that illegal and mercury-releasing ASGM needs termination, but such an action will result in the loss of the noted geological heritage value. Solution to this paradox requires careful development of plans for local management. However, it is clear that the presence of the noted heritage requires turning more attention to ASGM and their natural (river valley) context.

中文翻译：

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手工和小型金矿开采，蜿蜒的热带河流和地质遗迹：来自巴西和印度尼西亚的证据。

手工和小规模采金业（ASGM）在许多热带河流中蓬勃发展，在许多国家中仍需要适当的文件记录，并在合理的资源开发和野生动植物保护方面进行解释。在这项研究中，我们使用遥感技术分析了两例具有代表性的手工和小规模采金实例：一个是巴西马鲁帕河沿岸（塔帕约斯领地），另一个是印度尼西亚卡哈延河沿岸（加里曼丹中部）。已记录的ASGM的空间范围在马鲁巴河沿岸为〜9175 km2，在卡哈延河沿岸为〜30427 km2。可以确定，这些活动在太空中变化迅速（2-3年）。尽管这两个地区都有活跃和不活跃的地点，但马鲁巴河还是有很多不活跃的地点。沿着Marupa和Kahayan河流的ASGM与河道蜿蜒紧密相连，但同时也改变了河谷的形态，这一点至关重要。这是蜿蜒流域河流人类耦合形态动力学耦合的有趣证据。研究领域所代表的地质现象包括金矿资源开发（经济现象），地貌及其动力学（地貌现象）和汞环境污染（地球化学现象）。由于显着的空间范围和明显的相互联系，这些现象似乎是独特的，因此构成了地质遗产。后者的识别意味着ASGM网站为当地环境增加了价值。矛盾的是，非法和释放汞的手工和小规模采金需要终止，但是这种行为会导致所记录的地质遗产价值丧失。要解决此矛盾，就需要认真制定地方管理计划。但是，很明显，存在着重要的遗产需要将更多的注意力转向手工和小规模采金及其自然（河流谷地）环境。