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Volcanic and sedimentary facies, processes, and tectonics of intra-arc basins: Jurassic continental arc of California and Cretaceous oceanic arc of Baja California.

机译:弧内盆地的火山和沉积相,过程和构造:加利福尼亚的侏罗纪大陆弧和下加利福尼亚州的白垩纪海洋弧。

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摘要

Intra-arc basins are in general poorly defined and poorly understood. The tectonstratigraphic evolution of intra-arc basins in two arc sequences are analyzed: (1) the Jurassic continental arc of SW North America preserved in the Dome Rock sequence, Palen Mountains, California, and (2) the Cretaceous island arc terrane preserved in the Alisitos Formation, Baja California, Mexico. The Dome Rock sequence records the local initiation, development, and cessation of continental arc magmatism. Strata recording volcanic cessation are thinner than correlative rocks recording the same transition in Arizona. This may reflect more rapid arc dissection in California due to more strike-slip faulting relative to rifting.; The Alisitos Formation is part of a fringing island arc terrane. A stratovolcano and flanking fault- and volcano-bounded intra-arc basins preserved in a 50 km arc segment exhibit two evolutionary phases: (1) dominantly silicic- and intermediate pyroclastic rocks, followed by (2) dominantly basaltic effusive and hydroclastic deposits. Abundant associated dikes record an extensional episode. The coeval volcano- and fault-bounded basins have contrasting records resulting from: (1) destruction of pyroclastic flows entering the fault-bounded basin, due to steep, fault-scarp topography. (2) fault-facilitated magma ascent. (3) fault-facilitated voluminous mass wasting. (4) no rudist bioherm development or coarse bioclastic deposits in the fault-bounded volcano flank.; Abundant subaqueous pyroclastic flow deposits in the marine basins comprise four distinct types recognized on the basis of: (1) modification of the grain population, and (2) heat retention. Type I record high emplacement temperature and originate from hot, gas-fluidized pyroclastic flows. Type II are non-sorted, massive, and show record moderate heat retention. Type III record limited heat retention, and significant mixing with water. Type IV record no heat retention, but strong mixing with water. Types II-IV can originate: (1) from subaerial or submarine eruptions or (2) by remobilized hot or cold pyroclastic deposits. Granulometry discriminates nonmodified and modified deposits, supporting the textural classification. Distribution of the deposits reflects eruption dynamics, and mixing with the water column which can be controlled by sea floor roughness.
机译:一般来说,弧内盆地定义不清,了解甚少。分析了两个弧序列内弧内盆地的构造地层演化:(1)加利福尼亚州帕伦山穹顶岩序列中保存的北美西南侏罗纪大陆弧,以及(2)加利福尼亚州西南部保存的白垩纪岛弧地层。墨西哥下加利福尼亚州的Alisitos地层。圆顶岩层序记录了大陆弧岩浆作用的局部发生,发展和停止。记录火山停止的地层比记录亚利桑那州相同过渡的相关岩层薄。这可能是由于相对于裂谷更多的走滑断层,在加利福尼亚州弧的解剖更加迅速。 Alisitos组是边缘岛弧地层的一部分。保留在50 km弧段中的平流火山以及侧向断层和火山界的弧内盆地表现出两个演化阶段:(1)以硅质和中间热碎屑岩为主,其次是(2)以玄武质喷出性和水碎屑性沉积为主。大量相关联的堤防记录了一次延伸事件。中世纪的火山岩断层盆地与断层盆地具有相反的记录,其结果是:(1)由于陡峭的断层-陡峭的地形,破坏了进入断层边界盆地的火山碎屑流。 (2)断层促成岩浆上升。 (3)断层造成的大量质量浪费。 (4)在断层界定的火山侧面没有鲁斯生物礁或粗碎屑沉积物。海洋盆地中大量的水下火山碎屑流沉积物包括四种不同的类型,这些类型基于以下几个方面得到认可:(1)改变谷物种群,以及(2)保温。 I型记录了较高的进位温度,并源自热的,气化的火山碎屑流。 II型是未分类的,块状的,并显示出适度的保温性。 III型记录了有限的保温性,并且与水大量混合。 IV型记录没有保温性,但与水强烈混合。 II-IV型可以源自:(1)来自地下或海底喷发,或(2)来自热或冷的火山碎屑沉积物。粒度分析可区分未改性和改性的沉积物,从而支持质地分类。沉积物的分布反映了喷发动态,并与水柱混合,可以通过海底粗糙度来控制。

著录项

  • 作者单位

    University of California, Santa Barbara.;

  • 授予单位 University of California, Santa Barbara.;
  • 学科 Geology.
  • 学位 Ph.D.
  • 年度 1997
  • 页码 248 p.
  • 总页数 248
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;
  • 关键词

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