The post-collisional Syunik and Vardenis volcanic highlands, located in the southern Lesser Caucasus mountains (part of the Arabia-Eurasia collision zone) are host to over 200 monogenetic volcanoes, as well as 2 large Quaternary polygenetic volcanoes in the Syunik highland. The latter are overlain by lavas from the monogenetic volcanoes, suggesting there was a transition in the style of volcanic activity from large-volume central vent eruptions to dispersed small-volume eruptions. 12 new high quality ⁴⁰Ar/³⁹Ar ages are presented here, with 11 ages calculated by step-heating experiments on groundmass separates, and the final age obtained from total fusions of a population of sanidines. All the ages were younger than 1.5 Ma, except for one ignimbrite deposit whose sanidines gave an age of 6 Ma. While the bulk of the exposed products of post-collisional volcanism relate to Pleistocene activity, it is clear there has been active volcanism in the region since at least the late Miocene. All ages for monogenetic volcanoes in the Syunik highland are younger than 1 Ma, but to the north in Vardenis there is geochronological evidence of monogenetic volcanism at 1.4 and 1.3 Ma. An age of 1.3 Ma is determined for a lava flow from one of the polygenetic volcanoes- Tskhouk, and when combined with other ages helps constrain the timing of the polygenetic to monogenetic transition to around 1 Ma. The new ages illustrate a degree of spatio-temporal coupling in the formation of new vents, which could be related to pull-apart basins focussing ascending magmas. This coupling means that future eruptions are particularly likely to occur close to the sites of the most recent Holocene activity. The polygenetic to monogenetic transition is argued to be the result of a decreasing magma supply based on: (i) volume estimates for Holocene eruptions and for all monogenetic volcanoes and their lava flows in Syunik; and (ii) the volcanic stratigraphy of the Lesser Caucasus region which shows late Pliocene- early Pleistocene continental flood basalts being succeeded by a few large andesite-dacite volcanoes and then the most recent deposits consisting of small-volume scoria cones. The Syunik highland has the highest density of monogenetic centres in the Lesser Caucasus, which is taken to indicate this region has the highest magma flux, and was therefore the last location to transition to monogenetic volcanism, which is why the transition is most clearly seen there. There is no evidence from Sr-Nd-B isotope measurements for the exhaustion of fusible slab components in the mantle source, showing that an inherited slab signature can survive for millions of years after the end of subduction. Although volcanism in the Lesser Caucasus is currently waning, a future pulse of activity is possible.

碰撞后的Syunik和Vardenis火山高地位于小高加索山脉南部（阿拉伯-欧亚大陆碰撞带的一部分），是Syunik高地上200多个单基因火山以及2个大型第四纪多基因火山的宿主。后者被单相火山的熔岩覆盖，这表明火山活动的方式已经从大体积的中央喷口喷发向分散的小体积喷发过渡。12种新的高质量⁴⁰ Ar / ³⁹此处列出了Ar年龄，其中11个年龄是通过对地面物质分离物进行分步加热实验计算得出的，最终年龄是由一群山梨苷的完全融合获得的。所有年龄都小于1.5 Ma，唯一的例外是其中的一种火成岩沉积物的Sanidine年龄为6 Ma。虽然碰撞后火山活动的大部分裸露产物与更新世活动有关，但很明显，至少自中新世晚期以来，该地区一直存在活跃的火山活动。Syunik高地的单基因火山的所有年龄都小于1 Ma，但是在Vardenis的北部，有地质年代学证据表明1.4和1.3 Ma的单基因火山。确定了多生代火山之一Tskhouk的熔岩流年龄为1.3 Ma。当与其他年龄相结合时，有助于将多基因向单基因过渡的时间限制在1 Ma左右。新纪元说明了新火山口形成中的时空耦合程度，这可能与集中于上升岩浆的拉脱盆地有关。这种耦合意味着将来的喷发特别可能发生在最近的全新世活动的附近。据认为，多基因型向单基因型的过渡是岩浆供应减少的结果，其依据是：（i）全新的喷发量以及在Syunik的所有单基因火山及其熔岩流的体积估计；（ii）小高加索地区的火山地层，显示上新世晚期至更新世早期大陆性玄武岩先后由几座大型安山岩-针铁矿火山，然后是由小体积的鳞状锥构成的最新沉积。Syunik高地在小高加索地区具有最高的单基因中心密度，这表明该区域具有最高的岩浆通量，因此是向单基因火山过渡的最后一个地点，这就是为什么在那里最清楚地看到这种过渡的原因。 。Sr-Nd-B同位素测量没有证据表明地幔源中的易熔板块耗尽，表明继承的板块签名在俯冲结束后可以存活数百万年。尽管小高加索地区的火山活动目前正在减弱，