The Ferrar Magmatic Mush Column System, Dry Valleys, Antarctica

该奖项由极地方案办公室南极地质和地球物理方案提供，支持通过研究南极菲拉尔群的岩床来研究岩浆结晶过程。地球的基本结构是通过涉及岩浆或熔岩结晶的过程而形成的。数十亿年来，这些过程的运作产生了各种各样的岩石类型，而这些岩石类型又形成了地球的基本表面特征，即大陆和海洋盆地。然而，这些物理和化学过程的细节在很大程度上仍未被发现。尽管今天的火山作用通过喷发的各种熔岩说明了这种整体的分化过程，但尚不清楚这种戏剧性的最终结果如何与导致这一结果的长期和详细的深度过程有关。曾经埋藏很深，现在由于侵蚀而暴露出来的岩浆固化体(称为深成岩)也提供了证据，但大多数情况下，这些深成体在岩浆-火山系统中的背景并不清楚。本研究的目的是通过研究南极洲一组独特地显示这些岩浆作用的岩浆岩，为解决这一根本问题做出重大贡献。它们揭示了深成作用与火山作用的关系，可能是理解行星岩浆的重要关键。新兴的全球范例，即下面连接到深层岩浆源，上面连接到火山中心的一叠岩浆片或岩床，南极洲干燥山谷的费勒岩浆系统(Ferrar-DV)就是一个例子。世界上主要的岩浆系统(即，在洋脊、基拉韦厄、芒特。Etna、Stillwater和Rum等)也倾向于展示这种风格的系统，但只有Ferrar-DV清楚地揭示了深层、泥浆主导的系统和近地表之间的关键物理和化学联系。喷发前的底床系统。例如，在最深的层面上，一个广泛的充满泥浆的超镁铁质岩床形成了一个小(400米)的层状侵入体，具有许多类似成分的最大层状侵入体的共同特征，如杜菲克和斯蒂尔沃特。向上移动，主要形成泥浆的大的斜方辉石(OPX)晶体和较小的斜长石逐渐丧失，导致分化的拉斑玄武岩岩床。以前广泛的同时代和化学上连续的熔岩(柯克帕特里克玄武岩)完成了这个非常完整、异常暴露和广泛(约10,000立方千米)的岩浆系统。以前在约3,000平方公里范围内追踪OPX泥舌的工作揭示了一堆以冷杉树干和树干方式相互连接的岩床的雷头状填充模式。OPX舌头记录了一个间歇性的基座就位序列，加上个别基座本身的脉动填充。费拉尔-DV系统的表观侵位节奏与深成和火山系统相似。此外，尽管分层在富含OPX的语言中普遍存在，并仅限于这种语言，但在一个地点(讲台)，分层在许多尺度(毫米到米)上形成得特别好，表现出冲刷和填充、涟漪和其他形式的分类。台上相对较小的岩浆体和较高的地壳水平允许快速淬火，独特地保存了大型岩浆系统中通常因退火而丢失的结构。该项目旨在确定费拉尔-DV岩浆系统的全部物理和化学性质。主要目标是全面描绘其垂直和水平范围；了解其建立的动力学；了解Dais层状侵入体的形成机制；绘制整个干燥山谷的Ferrar岩石图；以及制作OPX舌状和进给器系统的三维模型。总体而言，该项目将试图阐明深成岩系和火山系统之间罕见的过渡，这很可能对北半球的行星岩浆活动具有根本意义。

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports research on magma crystallization processes through studies of sills of the Ferrar Group in Antarctica.Earth's basic structure came about through processes involving the crystallization of magma or molten rock. The operation of these processes over billions of years has produced a wide diversity of rock types that have in turn given rise to the basic surface features of Earth, namely, continents and ocean basins. Yet the very details of these physical and chemical processes remain largely undiscovered. Although present day volcanism exemplifies this overall process of differentiation through the variety of lava erupted, it is not clear how this dramatic end result relates to the prolonged and detailed processes at depth responsible for this result. Solidified bodies of magma (called plutons), once deeply buried and now exposed through erosion, also furnish evidence, but most often the context of these plutons within the magmatic-volcanic system is not clear. The aim of the present research is to make a significant contribution to solving this fundamental problem by studying a group of magmatic rocks in Antarctica that uniquely display these magmatic processes. They expose the relationship of plutonism to volcanism and may be an important key to understanding planetary magmatism.The emerging global paradigm of a stack of magmatic sheets or sills connected below to a deep-seated magmatic source and above to a volcanic center is exemplified by the Ferrar magmatic system of the Dry Valleys, Antarctica (Ferrar-DV). The world's major magmatic systems (i.e., at ocean ridges, Kilauea, Mt. Etna, Stillwater, and Rum, among many others) tend also to exhibit this style of system, but only the Ferrar-DV clearly reveals the critical physical and chemical connections between the deep, mush-dominated system and the near-surface. pre-eruptive sill system. At the deepest level, for example, an extensive mush-filled, ultramafic sill forms a small (400 m) layered intrusion with many features common to the largest layered intrusions of similar composition such as Dufek and Stillwater. Moving up-section, the progressive loss of large crystals of orthopyroxene (opx), which largely form the mush, and smaller plagioclase leads to differentiated tholeiitic sills. Formerly extensive coeval and chemically contiguous lavas (Kirkpatrick Basalt) complete this remarkably complete, exceptionally exposed, and extensive (~10,000 cubic-km) magmatic system.Previous work in tracing the opx mush tongue over an area of ~3,000 sq.-km has revealed the thunderhead-like filling pattern of a stack of sills interconnected in the fashion of the limbs and trunk of a fir tree. The opx tongue records an episodic sequence of sill emplacement coupled with pulsative filling of the individual sills themselves. The apparent emplacement rhythm of the Ferrar-DV system is akin to both plutonic and volcanic systems. Moreover, although layering is pervasive within, and confined to, the opx-rich tongue, at one locale (the Dais) the layers are particularly well formed on many scales (mm to m) and show scour and fill, ripples and other forms of sorting. The relatively small size and high crustal level of the magma body at the Dais allowed rapid quenching, uniquely preserving textures commonly lost to annealing in large magma systems.This project seeks to ascertain the full physical and chemical nature of the Ferrar-DV magmatic system. The major goals are to delineate fully its vertical and horizontal extent; to understand the dynamics of its establishment; to understand the mechanics of formation of the Dais layered intrusion; to produce a map of Ferrar rocks throughout the Dry Valleys; and to produce a 3-D model of the opx tongue and feeder system. Overall, the project will attempt to elucidate a rarely seen transition between plutonic and volcanic systems, which may well have implications fundamental to planetary magmatism in the b