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首页> 外文学位 >Investigation of arc processes: Relationships among deformation, magmatism, mountain building, and the role of crustal anisotropy in the evolution of the Peninsular Ranges Batholith, Baja California (Mexico).
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Investigation of arc processes: Relationships among deformation, magmatism, mountain building, and the role of crustal anisotropy in the evolution of the Peninsular Ranges Batholith, Baja California (Mexico).

机译：电弧过程的研究：变形，岩浆作用，山体构造以及地壳各向异性在下加利福尼亚州巴基索斯半岛山脉演化中的作用。

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摘要

Detailed structural and geochronological studies of a spectacularly exposed region of Baja California have revealed the structural evolution and links between orogenic processes at mid- to upper crustal levels of the Mesozoic Cordilleran magmatic arc system. The Jura-Cretaceous Peninsular Ranges batholith (PRB) of southern and Baja California contains one of the most remarkable examples of a crustal transition between oceanic- and continental-floored arcs in the world. Within this transition is an enigmatic belt of contractional deformation that stretches at least 800 km along the batholith and corresponds with a dramatic eastward increase in exposed crustal depths. In the Sierra San Pedro Martir of northern Baja California a spectacular ∼20 km-wide, contractional, doubly vergent fan structure occurs across the PRB basement transition. This structure formed over a period of >40 m.y. during intrusion of the batholith and consists of mylonitic, inward-dipping marginal thrust sheets that gradually change to a steeply-dipping zone of mylonite gneiss in the center. More than 15 km of differential exhumation occurred across the western side of the fan structure in Late Cretaceous time.; The mechanical effects of inherited crustal heterogeneity, including the basement transition zone in the batholith and a crustal buttress to the east, played a major role in the evolution of the fan structure. Intrusion of an extensive, sheeted plutonic complex in the center of the fan created rheological contrasts within the arc that led to partitioning of deformation for a limited period of time. Variation in crustal structure across the PRB also determined the extent and dynamics of uplift and denudation during mid- to Late Cretaceous evolution of the batholith, possibly including an Andean-style orogenic plateau across its eastern half. A portion of the western side of the batholith in this region appears to have collided with the North American margin in late Early Cretaceous time, but the effects of this event on the margin were masked by subsequent orogenesis that affected much of the southern Cordillera.
机译：对下加利福尼亚州一个引人注目的裸露区域进行的详细结构和年代学研究表明，中生代山脉山脉岩浆弧系统的构造演化和中，上地壳造山过程之间的联系。加利福尼亚南部和下加利福尼亚州的侏罗-白垩纪半岛山脉基岩（PRB）包含了世界上大洋和大洋洪水弧之间地壳过渡的最杰出例子之一。在这一过渡过程中，一条神秘的收缩变形带沿着岩基至少延伸了800公里，并且与暴露的地壳深度向东急剧增加相对应。在下加利福尼亚州北部的Sierra San Pedro Martir山脉，整个PRB地下室过渡处出现了一个壮观的〜20 km宽的，收缩的，双重的扇形结构。这种结构在> 40 m.y.的时期内形成。在岩基岩侵入过程中，由向内浸入的绵绵质边缘冲断片组成，逐渐向中心处的绵达麻岩片麻岩的陡倾带变化。白垩纪晚期，扇形构造的西侧发生了超过15 km的差异发掘。继承的地壳非均质性的机械效应，包括岩基的基底过渡带和东部的地壳支撑，在扇形结构的演化中起着重要作用。在风扇中央侵入大量片状的深部复合体，在弧内产生流变对比，从而在有限的时间内导致变形分配。整个PRB的地壳结构变化也决定了白蜡岩中晚期至白垩纪演化过程中隆升和剥蚀的程度和动力学，可能包括其东半部的安第斯式造山带高原。在该地区，部分岩基岩的西侧似乎与早白垩世时期的北美边缘发生了碰撞，但随后的造山运动掩盖了该山脉南部的大部分地区，从而掩盖了该事件对边缘的影响。

著录项

  • 作者

    Schmidt, Keegan Lee.;

  • 作者单位

    University of Southern California.;

  • 授予单位 University of Southern California.;
  • 学科 Geology.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 310 p.
  • 总页数 310
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;
  • 关键词

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