Abstract The back-arc southern Puna region (south of ~24°S) in the Central Volcanic Zone of the Andes contains hundreds of Miocene to Quaternary mafic monogenetic volcanoes roughly distributed in several volcanic fields. Analysis of the geomorphology, morphometry, spatial distribution and age of 36 mafic monogenetic centers in the Peinado and Incahuasi fields, at the southwestern margin of the Puna plateau, gives insights on the links that mafic monogenetic volcanism can have with main and secondary structures, and the effects of degradation on scoria cone shape. Degree of preservation, morphometry and six new unspiked K-Ar ages indicate two distinct age groups, old centers > 2 Ma and young centers ≤ 1 Ma. The older mafic centers consist of degraded scoria cones and lava flows with an estimated cumulative bulk volume of 2.2 km3. The younger mafic centers display a variety of well-preserved landforms (scoria cones, lava flows, maars, tuff rings, domes) and have an estimated cumulative volume of 6.2 km3. Their distribution in a main NNE-SSW and secondary ENE-WSW trends suggests a control by the regional NNE-SSW striking Peinado and San Francisco fault systems in a dextral strike-slip configuration. Scoria cone and lava flow morphometries are similar in both fields, but a marked difference indicating hydrovolcanic activity is the presence of tuff rings, maars and tephra fallout deposits only in the Peinado field. Morphometric analysis of dated pristine and degraded scoria cones of the southern Puna region shows that parameters related to crater depth and inner crater steepness decrease consistently with age, suggesting that crater infilling is the degradation-related process that is most sensitive to age at scoria cones. In the southern Puna, high values of crater depth/crater width, crater depth/cone height and mean inner crater slope are indicative of a young ( 1 Ma) age, as young cones can have initially low values.

中文翻译：

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安第斯山脉最南端中央火山带 Peinado 和 Incahuasi 油田基性火山的地貌、形态测量、空间分布和年龄

摘要 安第斯山脉中央火山带弧后南部普纳地区（~24°S 以南）包含数百座中新世至第四纪基性单生火山，大致分布在几个火山区中。对普纳高原西南边缘 Peinado 和 Incahuasi 油田 36 个基性单晶中心的地貌、形态测量、空间分布和年龄的分析，揭示了基性单晶火山活动与主要和次要结构之间的联系，以及降解对熔渣锥形状的影响。保存程度、形态测量和六个新的未加标 K-Ar 年龄表明两个不同的年龄组，老中心 > 2 Ma 和年轻中心 ≤ 1 Ma。较旧的镁铁质中心由退化的火山渣锥和熔岩流组成，估计累积体积为 2.2 立方千米。较年轻的镁铁质中心显示出各种保存完好的地貌（火山渣锥、熔岩流、火山口、凝灰岩环、圆顶），估计累积体积为 6.2 平方公里。它们在主要的 NNE-SSW 和次要的 ENE-WSW 趋势中的分布表明，区域性 NNE-SSW 以右旋走滑构造撞击 Peinado 和旧金山断层系统。两个油田的火山渣锥和熔岩流形态测量相似，但表明水火山活动的显着差异是仅在 Peinado 油田存在凝灰岩环、玛尔和火山灰沉积物。对普纳南部地区年代久远的原始和退化的火山渣锥体的形态测量分析表明，与陨石坑深度和内部陨石坑陡度相关的参数随着年龄的增长而持续下降，表明火山口填充是与降解相关的过程，对火山渣锥的年龄最敏感。在普纳南部，火山口深度/火山口宽度、火山口深度/锥体高度和平均内部火山口坡度的高值表明年轻 (1 Ma) 年龄，因为年轻的锥体最初可能具有低值。