Facies Architecture and Depositional Processes Resulting from Intra-Basinal Maar Volcanism, Hopi Buttes, NortheasternArizona

这项研究的主要目标是确定盆地内火山作用，特别是玛尔火山作用对低地沉积的影响。调查将在亚利桑那州东北部的Hopi Buttes火山田进行，重点是中上新世Bidahochi组的沉积过程和由此产生的岩相结构。这包括河流和湖床沉积的互层，重新加工的盖夫拉，未重新改造的盖夫拉代表马尔火山喷发边缘，以及马尔火山口充填序列。第二个目标是将从比达霍奇组沉积学研究得出的地表环境(站立湖、干滩、短暂溪流)的“湿度”与通过研究马阿尔火山的沉积特征和火山喷发边缘的火山碎屑形态而得出的“湿度”的独立估计进行比较。MAAR油田是复杂的沉积环境。马尔火山本身既是沉淀源(喷发的火山灰)，也是沉淀池(陨石坑可以捕获流经的溪流)。如果不了解沉积盆地内的沉积过程和火山作用，就无法解释由此产生的相结构。霍皮巴特斯地区是研究的理想之地。在与峭壁接壤的悬崖上，暴露是极好的和持续的，侵蚀暴露了系统的不同层次，从喷发的古表面略上方到许多火山口沉积物的底部。

The primary goal of this research is to determine the effect of intrabasinal volcanism, specifically maar volcanism, upon lowland sedimentation. The investigation will be carried out in the Hopi Buttes volcanic field of northeastern Arizona, and will focus upon the depositional processes and resulting lithofacies architecture of the Mio-Pliocene Bidahochi Formation. This comprises fluvial and lake-bed deposits of interbedded, reworked tephra, un-reworked tephra representing the ejecta rims of maar volcanoes, and maar crater-filling sequences. A secondary objective is to compare the "wetness" of the surficial environment (standing lake, dry playa, ephemeral streams) inferred from the sedimentological study of the Bidahochi Formation with independent estimates of "wetness" derived from study of the depositional features and pyroclast morphology of the maar volcanoes' tephra rims. Maar fields are complex depositional environments. The maar volcanoes themselves are both sediment sources (erupted tephra) and sinks (the craters can capture through-flowing streams). The resulting facies architecture cannot be interpreted without understanding both the sedimentary and the volcanic processes operating within the depositional basin. The Hopi Buttes area is ideal for the study. Exposures are excellent and continuous in cliffs bordering the buttes, and erosion has exposed various levels of the system, from slightly above the paleo-surface of eruption to the bases of many crater deposits.