Most descriptions of obsidian-bearing rhyolitic lava flows and domes are largely based on relatively simple cases of tectonic plate subduction in North America, but Armenian geologists proposed since the 1960s that these models are less suitable for describing rhyolitic volcanism in their research area. Obsidian-producing volcanoes that lie in the Armenian Highlands, they argued, are more complex in form and stratification. Hatis volcano in central Armenia is one such example. As we document, Hatis is highly unusual, perhaps unique, in that its obsidian changes in composition with elevation. Prior studies of Hatis obsidian recognized the existence of two different chemical types. Here, though, we report a series of four obsidian chemical types and their spatial distributions across the slopes. Our findings were enabled by the use of portable XRF during our field surveys of Hatis. Additionally, we recognized each of these four chemical types of Hatis obsidian at the Lower Palaeolithic site of Nor Geghi 1, where thousands of obsidian artifacts reflect Pleistocene hominin behaviors from Marine Isotope Stage (MIS) 11 (~424–374 ka) to 9 (~337–300 ka). Thus, all four types of Hatis obsidian are archaeologically significant despite the fact that their outcrops span more than 500 m (from <1600 to greater than 2100 m asl) in elevation on the volcanic slopes, thereby enabling future studies on links between altitude and hominin toolstone acquisition behaviors over hundreds of millennia.

大多数对含黑曜石流纹岩熔岩流和圆顶的描述主要基于北美构造板块俯冲的相对简单案例，但亚美尼亚地质学家自 1960 年代以来提出，这些模型不太适合描述其研究领域的流纹岩火山作用。他们认为，位于亚美尼亚高地的产黑曜石火山在形式和分层上更为复杂。亚美尼亚中部的哈蒂斯火山就是这样一个例子。正如我们记录的那样，Hatis 是非常不寻常的，也许是独一无二的，因为它的黑曜石成分随着海拔的升高而变化。先前对 Hatis 黑曜石的研究认识到存在两种不同的化学类型。不过，在这里，我们报告了一系列四种黑曜石化学类型及其在斜坡上的空间分布。我们的发现是通过在我们对 Hatis 的现场调查期间使用便携式 XRF 实现的。此外，我们在 Nor Geghi 1 的旧石器时代下遗址识别了这四种化学类型的 Hatis 黑曜石，其中数以千计的黑曜石文物反映了从海洋同位素阶段 (MIS) 11 (~424–374 ka) 到 9 ( ~337–300 ka）。因此，尽管它们的露头在火山斜坡上的海拔高度超过 500 m（从 <1600 到大于 2100 m asl），但所有四种类型的哈提斯黑曜石都具有考古意义，从而能够在未来研究海拔高度与古人类之间的联系数百年来的工具石获取行为。数以千计的黑曜石文物反映了从海洋同位素阶段 (MIS) 11 (~424–374 ka) 到 9 (~337–300 ka) 的更新世人类行为。因此，尽管它们的露头在火山斜坡上的海拔高度超过 500 m（从 <1600 到大于 2100 m asl），但所有四种类型的哈提斯黑曜石都具有考古意义，从而能够在未来研究海拔高度与古人类之间的联系数百年来的工具石获取行为。数以千计的黑曜石文物反映了从海洋同位素阶段 (MIS) 11 (~424–374 ka) 到 9 (~337–300 ka) 的更新世人类行为。因此，尽管它们的露头在火山斜坡上的海拔高度超过 500 m（从 <1600 到大于 2100 m asl），但所有四种类型的哈提斯黑曜石都具有考古意义，从而能够在未来研究海拔高度与古人类之间的联系数百年来的工具石获取行为。