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首页> 外文学位 >Tectonic evolution of northern Ellesmere Island: Insights from the Pearya Terrane, Ellesmerian clastic wedge and Sverdrup Basin.
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Tectonic evolution of northern Ellesmere Island: Insights from the Pearya Terrane, Ellesmerian clastic wedge and Sverdrup Basin.

机译：北部Ellesmere岛的构造演化：来自Pearya Terrane，Ellesmerian碎屑楔和Sverdrup盆地的见解。

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摘要

The tectonic evolution of northern Ellesmere Island is dominated by the accretion of the Pearya Terrane and the progressive reworking of materials from the Pearya Terrane and the northern Caledonides. Geochronology from a suite of seven Succession I orthogneiss samples defines a range of earliest Neoproterozoic ages from 962 ± 6 Ma to 974 ± 8 Ma. Geochemistry of both zircon and whole rock samples reveal a complex magmatic history tapping multiple sources. The rocks include both I and S type granitoids, with silica contents ranging from 62% to 73%. Trace element geochemistry reveals LILE enrichment decoupled from low to depleted HFSE values, suggestive of an origin above a subduction zone. Isotope geochemistry supports input from juvenile and evolved materials, with ϵNd(i) values between -1 and -4.6, and a similar range for ϵHf from zircon. The northern elements of the Caledonian Orogen preserve a record of magmatism in the c. 985 Ma to 920 Ma range. These ages are also observed in orthogneiss units of the south central Brooks Range and Farewell terrane, Alaska. The Pearya Terrane orthogneiss units and those currently dispersed in Alaska are interpreted to have originated near or on the eastern margin of Greenland and record post-Rodinia assembly subduction outboard of the supercontinent.;Succession II (Trettin, 1987) of the Pearya Terrane represents variably metamorphosed metasedimentary rocks of Proterozoic to early Paleozoic age. These units are structurally juxtaposed with Succession I orthogneiss and Paleozoic sedimentary units of the Pearya Terrane. Detrital zircon age spectra from seven samples of Neoproterozoic meta-sedimentary rocks reveal three groups defined by observed dominant age peaks and youngest observed age populations. Group I includes three quartzite samples and contains numerous c. 1100 Ma to 1800 Ma peaks, with the youngest population at c. 1050 Ma. Two samples of immature meta-sandstone form Group II, defined by a dominant c. 970 Ma age peak. Two samples from the diamictite unit below the Deutchers Glacier thrusts form Group III, with a similar pattern of c. 1000 Ma to 1800 Ma age peaks to Group I; however, this group includes a small population of c. 600 Ma to 700 Ma grains as well. The ubiquitous Mesoproterozoic ages reflect a Grenvillian-Sveconorwegian provenance. These data are consistent with detrital zircon datasets from other North Atlantic-Arctic Caledonide terranes, reinforcing stratigraphic links between the Pearya Terrane and the northern Caledonides. The utility of the Pearya Terrane dataset is multiplied by probable links to Circum-Arctic and Cordilleran terranes, many of which contain similar populations of Mesoproterozic-aged detrital zircon.;U/Pb ages and Hf isotopic data from detrital zircon suites sampled from Ordovician to Carboniferous sedimentary rock of the Pearya Terrane and northern Ellesmere Island record define the background for terranes translating along the northeastern Laurentian margin in the Paleozoic. Ordovician to Silurian clastic sediments deposited on the Pearya Terrane record pre terrane accretion provenance dominated by recycling of the metaigneous and metasedimentary Proterozoic basement as well as an Ordovician arc source. The provenance of Late Devonian sediments deposited during the Ellesmerian Orogen is dominated by similar recycled materials, with new sources derived from Paleoproterozoic domains of the Canadian-Greenland shield and documented late Devonian granitoids emplaced the Canadian Arctic Islands and Arctic Alaska. The basal Sverdrup Basin records increasing proportions of Paleoprtoerozoic and Archean aged grains relative to Mesoproterozoic ages, suggestive of increased contributions from the Laurentian craton and no little detritus exotic to Laurentia. Detrital zircon age spectra from Devonian to Carboniferous sediments in the northern Cordilleran clastic wedge and western Canadian Arctic Islands contain abundant exotic zircon likely derived from the Caledonian and Timanian Orogens. This variance of sediment provenance indicates that the eastern Canadian Arctic Island were isolated from non-Laurentian or Caledonian detritus, and that sources of the exotic Timanian zircon reconstruct farther west along the margin.
机译：北部埃勒斯米尔岛的构造演化主要由Pearya Terrane的增生以及Pearya Terrane和北部Caledonides的材料的逐步改良所主导。来自一组七个继承I直生片样品的地质年代学定义了最早的新元古代年龄范围，从962±6 Ma到974±8 Ma。锆石和整个岩石样品的地球化学揭示了利用多种来源的复杂岩浆历史。岩石包括I型和S型花岗岩，二氧化硅含量在62％至73％之间。痕量元素地球化学表明，LILE富集从低至贫化的HFSE值解耦，暗示了俯冲带以上的成因。同位素地球化学支持少年和演化材料的输入，εNd（i）值介于-1和-4.6之间，锆石的εHf的范围相似。加里东造山带的北部元素保留了c岩浆的记录。 985 Ma至920 Ma范围。这些年龄在布鲁克斯山脉中南部和阿拉斯加的告别地带的直生片岩单元中也观察到。 Pearya Terrane Orthogneiss单位和目前分散在阿拉斯加的单位被解释为起源于格陵兰东部边缘附近或之上，并记录了超大陆外罗迪尼亚集会俯冲之后的情况。Pearya Terrane的继任II（Trettin，1987）代表不同变质的元古代至早古生代沉积沉积岩。这些单元在构造上与Pearya Terrane的继承I直生片岩和古生代沉积单元并列。来自七个新元古代中期沉积岩样品的碎屑锆石年龄谱揭示了三组，分别由观察到的主导年龄峰和观察到的最小年龄种群确定。第一组包括三个石英岩样品，并包含大量c。高峰期1100 Ma至1800 Ma，最小的种群为c。 1050马。未成熟的亚砂岩的两个样本形成第二组，由显性c定义。 970高峰年龄。来自Deutchers冰川冲断层下面的透硅铝石单元的两个样品形成了III组，具有相似的c模式。第一组的年龄在1000 Ma至1800 Ma之间。但是，此组中只有一小部分c。 600 Ma至700 Ma晶粒也是如此。中古生代时代无处不在，反映出格伦维利安-斯韦科诺维克血统。这些数据与其他北大西洋-北极喀里多尼德地层的碎屑锆石数据集一致，从而加强了皮亚拉（Pearya）地形与北喀里多尼德之间的地层联系。 Pearya Terrane数据集的实用性乘以到Circum-Arctic和Cordilleran地形的可能链接，其中许多包含中元古代年龄的碎屑锆石种群； U / Pb年龄和从奥陶纪至奥陶纪取样的碎屑锆石套件中的Hf同位素数据Pearya Terrane和北部Ellesmere Island记录的石炭纪沉积岩为古生代东北Laurentian边缘东北平移的地层定义了背景。沉积在Pearya Terrane上的奥陶纪至志留纪碎屑沉积物记录了地前增生物源，主要是通过重新沉积了火成岩和准沉积的元古代基底以及奥陶纪弧源。 Ellesmerian造山带中沉积的晚泥盆世沉积物的来源主要由相似的可回收材料组成，新的来源来自加拿大格陵兰盾构的古元古界，并且有记载的晚泥盆纪花岗岩分布在加拿大的北极岛和北极的阿拉斯加。底部的斯维尔德鲁普盆地记录了古生代和太古代的谷物相对于中古生代的比例增加，这表明劳伦斯克拉通的贡献增加了，而劳伦西亚则几乎没有碎屑。北部山脉山脉碎屑楔和加拿大西部北极群岛泥盆纪至石炭纪沉积物的碎屑锆石年龄谱含有丰富的稀有锆石，这些锆石很可能来自加里东和Timanian造山带。沉积物出处的这种差异表明，加拿大东部北极岛是与非劳伦系或喀里多尼亚系碎屑隔离的，奇异的Timanian锆石的来源沿边缘向西延伸。

著录项

  • 作者

    Malone, Shawn Joseph.;

  • 作者单位

    The University of Iowa.;

  • 授予单位 The University of Iowa.;
  • 学科 Geology.;Geochemistry.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 295 p.
  • 总页数 295
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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