Mantled Gneiss Domes in the Albion Range, Southern Idaho
Mantled Gneiss Domes in the Albion Range, Southern Idaho
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爱达荷州南部阿尔比恩山脉的披覆片麻岩圆顶
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发表时间：
1968
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影响因子：
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通讯作者：
R. Armstrong
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作者：
R. Armstrong
阿尔比恩山脉位于爱达荷州南部，安特勒造山带以东，塞维尔造山带以西，暴露出一条由四个地幔片麻岩穹丘组成的东北走向链。绿色溪杂岩（前寒武纪[2.5 b.y.]片麻岩和变质沉积物），形成了圆顶的核心，不整合地覆盖着古生代鸽溪群，由约22，000英尺厚的稀疏含矿变质沉积物组成。基底石英岩和上覆的片岩、大理石和薄石英岩的时代可能是寒武纪。块状石英岩及其上覆的片岩和石灰岩的时代可能是寒武纪或奥陶纪。在变质沉积剖面的中部为厚度超过7000英尺的奥陶纪石英岩，其上覆有块状纯白云岩、钙质黑色片岩和奥陶纪至密西西比纪（？）年龄泥盆纪地层薄或缺失。在变质沉积岩段的顶部是宾夕法尼亚期Oqualeh（？）阵晚古生代砂岩、灰岩、硅质岩和三叠系（？）页岩出现在覆盖变质沉积物的断层接触面中。新生代沉积岩和火山岩不整合地覆盖在变形的老岩石之上。变质程度（绿片岩相和角闪岩相）在该地区向西北和向下逐渐增加。十字石和蓝晶石出现在寒武纪岩石的北方的范围;堇青石，红柱石，和硅线石出现在前寒武纪岩石的范围的南半部，但这些可能是由于第三纪接触变质。中生代变质作用期间的变形产生了两个组构系统;局部的前寒武纪变质组构幸存下来的年轻变质作用。早期的层理面理和东北走向、西北走向的褶皱和线理早于穹丘的上升。在拱起过程中和拱起之后，产生了西北走向的褶皱和走向东北和西南的线理;在山脉西半部的大部分地区，这些结构破坏了所有较老的结构。渐新世（30百万年）运动后的二长花岗岩群--阿尔莫冥王星--和相关的花岗岩脉被侵位。在岩体就位后，山脉的抬升速度加快到平均每年0.5毫米，将片麻岩圆顶从至少10公里的深度带到地表。阿尔比恩山脉是沿着科迪勒拉山脉微地槽西部的一个岩石带的一部分，在中生代中期受到高级区域变质作用的影响。这些变质岩是科迪勒拉山脉基础设施的一部分，可以追溯到从加州到不列颠哥伦比亚省南部以及更远的地方。
The Albion Range, in southern Idaho east of the Antler orogenic belt and west of the Sevier orogenic belt, exposes a northeast-trending chain of four mantled gneiss domes. The Green Creek Complex (Precambrian [2.5 b.y.] gneiss and metasediments), which forms the cores of the domes, is unconformably overlain by the Paleozoic Dove Creek Group, consisting of sparsely fossiliferous metasediments approximately 22,000 feet thick. The basal quartzite and overlying schists, marbles, and thin quartzites are of probable Cambrian age. A massive quartzite and overlying schist and limestone may be Cambrian or Ordovician in age. Ordovician quartzite more than 7000 feet thick forms the middle part of the metasedimentary section, and this is overlain by massive pure dolomite, calcareous black schist, and quartzite of Ordovician through Mississippian(?) age. Devonian strata are thin or absent. At the top of the metasedimentary section are limestone, schist, and quartzite of the Pennsylvanian Oquirrh(?) Formation. Younger Paleozoic sandstone, limestone, and chert, and Triassic(?) shale occur in fault contact overlying the metasediments. Cenozoic sedimentary and volcanic rocks unconformably overlie the deformed older rocks. Metamorphic grade (greenschist and amphibolite facies) increases northwestward and downward in the area. Staurolite and kyanite occur in Cambrian rocks in the northern half of the range; cordierite, andalusite, and sillimanite occur in Precambrian rocks in the southern half of the range, but these may be due to Tertiary contact metamorphism. Deformation during Mesozoic metamorphism produced two fabric systems; locally a Precambrian metamorphic fabric survived the younger metamorphism. Early bedding foliation and northeast-trending, northwest-vergent folds and lineations predated rise of the domes. Northwest-trending folds and lineations with northeast and southwest vergence were produced during and after doming; over much of the western half of the range these structures destroyed all older fabrics. During the Oligocene (30 m.y.) a postkinematic adamellite stock—the Almo Pluton—and related granitic dikes were emplaced. Following emplacement of the pluton, uplift of the range accelerated to an average rate of .5 mm per year, bringing the gneiss domes to the surface from a depth of at least 10 km. The Albion Range is part of a belt of rocks along the western part of the Cordilleran miogeosyncline which was affected by high-grade regional metamorphism during the middle of the Mesozoic. The metamorphic rocks are part of the Cordilleran infrastructure, which can be traced from California into southern British Columbia and beyond.