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，特别是马尔火山作用，对低地沉积的影响。调查将在亚利桑那州东北部的霍皮巴特斯火山区进行，并将重点关注中-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层间，改造火山灰，未改造火山灰代表喷出物边缘的玛珥火山，玛珥火山口填充序列。第二个目标是比较从Bidahochi组的沉积学研究中推断出的地表环境的“湿度”（静止湖、干盐湖、临时溪流）与从玛珥火山火山口边缘的沉积特征和火山碎屑形态研究中得出的“湿度”的独立估计。玛珥气田是一个复杂的沉积环境。玛珥火山本身既是沉积物的来源（火山灰喷发），也是沉积物的下沉（火山口可以捕获贯穿的溪流）。如果不了解沉积盆地内的沉积和火山作用过程，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场所。暴露是优秀的和连续的悬崖接壤的孤峰，和侵蚀暴露了系统的各个层面，从略高于喷发的古表面到许多火山口沉积物的基础。

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.