Carboniferous and Permian Stratigraphy and Paleontology, Northern Yukon Territory, Canada
Carboniferous and Permian Stratigraphy and Paleontology, Northern Yukon Territory, Canada
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发表时间：
1971-03
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通讯作者：
E. Bamber;J. B. Waterhouse
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作者：
E. Bamber;J. B. Waterhouse
摘要 育空地区北部的石炭纪和二叠纪岩石由海相碳酸盐和页岩组成，并含有少量粗粒陆源碎屑。该序列的年龄范围从维西安（Meramecian）到卡赞尼亚（Guadalupian），并暴露在三个主要地区：北部的奥格尔维山脉 - 南部的皮尔河地区；西北部的英国-巴恩山脉地区；以及东北部的理查森山脉北部。几个区域不整合面下方明显的截断已经消除了这三个地区之间的大部分上古生界序列。在奥格尔维山脉北部 - 皮尔河地区厚厚且高度变化的序列中，识别出以下六个岩性单元（从底部到顶部）： 单元 1（含碳酸盐结核的页岩）；单元 1（含碳酸盐结核的页岩）；哈特河地层（新名称，含有燧石和页岩的细粒碳酸盐）；第2单元（碳酸盐和陆源碎屑）； Ettrain 地层（新名称，细粒至粗粒碳酸盐）； Jungle Creek Formation（新名称，陆源碎屑岩和碳酸盐岩）；和 Tahkandit 地层（细粒碳酸盐和燧石）。二叠系底部和中生代底部不整合面下的主要相变和截断导致了这些单元复杂的分布模式和地层关系。英国-巴恩山脉地区存在与阿拉斯加东北部相似的厚层上古生界层序，该地区的维西恩至莫斯科页岩以及卡亚克组和利斯本群的碳酸盐岩被区域不整合面与下面的涅鲁克普克组和上覆的未分异二叠纪岩石分开。从砂岩到页岩再到碳酸盐岩的渐变横向和纵向变化是 Kayak 地层的特征。利斯本群的上覆碳酸盐岩向东北方向表现出晶粒尺寸普遍减小和白云石比例增加。该地区整个上古生代地层的截断发生在亚三叠纪不整合面下方的北极沿海平原。理查森山脉北部厚厚的上古生代地层不像育空地区北部的其他地方那么完整，并且以陆源碎屑岩为主。在古老的阿克拉维克拱门以北，石炭纪（巴什基尔晚期或莫斯科）碳酸盐岩局部出现在下伏中泥盆统碳酸盐岩和上覆广泛分布的二叠纪砂岩、页岩和石灰岩之间。在拱形轴线附近和以南，二叠系位于上泥盆统和更古老的岩石上，并在次侏罗纪不整合面下方被截断，朝向鹰平原东北部。碳酸盐岩和碎屑岩相的构造表明，育空地区北部的石炭纪岩石在浅海条件下堆积在一条连续的西北走向的带中，该带延伸到理查森山脉现址以西的整个地区。维西恩页岩和细粒浅海碳酸盐的广泛沉积之后，碳酸盐岩浅滩发育，开始于维西恩晚期的不列颠 - 巴恩山脉地区，随后向南传播到北部的奥格尔维端_第 29 页----------------------------------------山脉 - 皮尔河地区，并在晚那穆里安（巴什基里安）至 ?Gshelian（？密苏里）时期占据主导地位。维西安时期，陆源碎屑和煤炭的堆积发生在该地区东北边缘的部分大陆条件下，并且可能一直持续到莫斯科时期（宾夕法尼亚州中部）。在石炭纪晚期和二叠纪早期，东北走向的阿克拉维克祖拱隆起横跨育空北部中部的过程中，发生了广泛的海退。对于英国-巴恩山脉地区来说，二叠纪沉积历史在很大程度上是未知的。在育空地区北部的其他地方，二叠纪早期发生了海侵，沉积作用在东北走向的相带中恢复，与石炭系的相带大致成直角。古老的阿克拉维克拱门控制了沉积作用，并在阿塞利安和萨克马里安（沃尔夫坎）时期为陆源碎屑提供了源区。在阿廷斯基期到卡赞期（伦纳德期到瓜达卢普期）时期，海侵向阿克拉维克拱中心的轴线方向推进，结果到了喀山期，拱门被海洋陆源碎屑岩和碳酸盐覆盖。育空地区没有关于二叠纪沉积的进一步记录。育空地区北部上古生界内的生物地层相关性主要基于腕足动物和有孔虫的分布，以及来自菊石、孢子和珊瑚的补充数据。腕足动物分布在 34 个分布广泛的区域和亚区域，其年龄范围从晚维西安期（切斯特期）到卡赞期期（瓜达卢普期）。描述了十七个新的腕足动物属和种，并说明了每个区域的典型形态。与这些腕足动物相关的有孔虫在该地区的石炭纪形成了许多区域，并且也出现在二叠纪的几个层面。育空地区动物群演替可分为 12 个主要生物地层单元，与北美西部和北极地区、斯匹茨卑尔根群岛、乌拉尔山脉和西伯利亚其他地区发现的动物群演替非常相似。此外，育空地区的动物群与新西兰和澳大利亚的动物群有细微但显着的相似之处。腕足动物群的变化表明，育空地区在石炭纪和二叠纪经历了与南半球类似的古气候波动。来自腕足动物群的证据表明，育空地区的古地理位置比古地磁数据显示的更接近二叠纪北极。
ABSTRACT Carboniferous and Permian rocks of the northern Yukon consist of marine carbonates and shales, with minor amounts of coarse-grained terrigenous clastics. The succession ranges in age from Visean (Meramecian) to Kazanian (Guadalupian), and is exposed in three main areas: the northern Ogilvie Mountains -- Peel River area in the south; the British - Barn Mountains area in the north-west; and the northern Richardson Mountains in the northeast. Pronounced truncation beneath several regional unconformities has removed much of the upper Paleozoic succession between these three areas. Within the thick, highly variable sequence of the northern Ogilvie Mountains - Peel River area, the following six lithologic units are recognized (base to top): Unit 1 (shale with carbonate nodules); Hart River Formation (new name, fine-grained carbonates with chert and shale); Unit 2 (carbonates and terrigenous clastics); Ettrain Formation (new name, fine- to coarse-grained carbonates); Jungle Creek Formation (new name, terrigenous clastic rocks and carbonates); and Tahkandit Formation (fine-grained carbonates and chert). Major facies changes and truncation beneath unconformities at the base of the Permian and at the base of the Mesozoic have given rise to complex distribution patterns and stratigraphic relationships for these units. A thick upper Paleozoic sequence similar to that in northeastern Alaska is present in the British - Barn Mountains area, where the Visean to Moscovian shales and carbonates of the Kayak Formation and Lisburne Group are separated by regional unconformities from the underlying Neruokpuk Formation and overlying undifferentiated Permian rocks. Gradational lateral and vertical changes from sandstone through shale to carbonate rocks characterize the Kayak Formation. The overlying carbonates of the Lisburne Group show a general decrease in grain size and an increase in the proportion of dolomite toward the northeast. Truncation of the entire upper Paleozoic succession of the area takes place toward the Arctic Coastal Plain beneath the sub-Triassic unconformity. The thick upper Paleozoic succession of the northern Richardson Mountains is less complete than elsewhere in the northern Yukon, and is dominated by terrigenous clastic rocks. North of the ancestral Aklavik Arch, Carboniferous (late Bashkirian or Moscovian) carbonates occur locally between underlying Middle Devonian carbonates and overlying, widespread Permian sandstone, shale, and limestone. Near the axis of the arch, and to the south, the Permian rests on Upper Devonian and older rocks, and is truncated beneath the sub Jurassic unconformity toward the northeastern Eagle Plain. The configuration of carbonate and clastic facies suggests that the Carboniferous rocks of the northern Yukon accumulated under shallow-marine conditions in a continuous northwest-trending belt extending throughout the area west of the present site of the Richardson Mountains. Widespread deposition of Visean shale and fine-grained, shallow-marine carbonates was followed by carbonate-shoal development, which began in the British - Barn Mountains area during the Late Visean, subsequently spread southward to the northern Ogilvie End_Page 29------------------------- Mountains - Peel River area, and became dominant during Late Namurian (Bashkirian) to ?Gshelian (?Missourian) time. Accumulation of terrigenous clastics and coal occurred under partly continental conditions along the north-eastern margin of the area during Visean time, and may have continued into the Moscovian (Middle Pennsylvanian). Extensive regression occurred in latest Carboniferous and earliest Permian time during uplift of the northeast-trending ancestral Aklavik Arch across the central part of the northern Yukon. Permian depositional history is largely unknown for the British - Barn Mountains area. Elsewhere in the northern Yukon, marine transgression occurred in the early Permian, and sedimentation resumed in northeast-trending facies belts, approximately at right angles to those of the Carboniferous. The ancestral Aklavik Arch controlled sedimentation and provided a source area for terrigenous clastics during Asselian and Sakmarian (Wolfcampian) time. In Artinskian to Kazanian (Leonardian to Guadalupian) time, marine transgression proceeded toward the axis of the ancentral Aklavik Arch, with the result that by Kazanian time the arch was covered by marine terrigenous clastics and carbonates. No further record of Permian sedimentation is known from the Yukon. Biostratigraphic correlations within the upper Paleozoic of the northern Yukon are based mainly on the distribution of brachiopods and foraminifers, with supplementary data from ammonoids, spores, and corals. Brachiopods occur in 34 widespread zones and subzones ranging in age from Late Visean (Chesteran) to Kazanian (Guadalupian). Seventeen new brachiopod genera and species are described, and typical forms from each zone are illustrated. Foraminifera associated with these brachiopods form numerous zones in the Carboniferous of the area and also occur at several levels in the Permian. The Yukon faunal succession is divisible into 12 major biostratigraphic units, and closely resembles faunal successions found elsewhere in western and arctic North America, Spitzbergen, the Ural Mountains, and Siberia. In addition, the Yukon faunas show minor but significant similarities to the faunas of New Zealand and Australia. Variations in brachiopod faunas indicate that the Yukon underwent paleoclimatic fluctuations in the Carboniferous and Permian similar to those that occurred in the southern hemisphere. Evidence derived from brachiopod faunas suggests that the Yukon occupied a paleogeographic position considerably closer to the Permian north geographic pole than is indicated by paleomagnetic data.