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

本研究的主要目的是确定基底内火山作用，特别是马尔火山作用对低地沉积的影响。此次调查将在亚利桑那州东北部的霍皮巴特斯火山场进行，并将重点研究中新世-上新世Bidahochi组的沉积过程和岩相结构。这包括河流沉积和湖床沉积的互层、改造过的毡层、未改造过的毡层代表着maar火山的喷出物边缘，以及maar陨石坑填充序列。第二个目标是比较从比达霍奇组沉积学研究推断的地表环境的“湿度”（活湖、干playa、短暂的溪流）与从马尔火山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。Maar油田是复杂的沉积环境。maar火山本身既是沉积物的来源（喷发的火山）也是沉积物的汇（火山口可以捕获流经的溪流）。如果不了解沉积盆地内的沉积作用和火山作用，就无法解释沉积相结构。霍皮山丘地区是这项研究的理想地点。在山岗附近的悬崖上，暴露的情况非常好，而且是连续的，侵蚀已经暴露了该系统的不同层次，从火山喷发的古表面略高于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.