scholarly journals Pre-Mississippian Stratigraphic Architecture of the Porcupine Shear Zone, Yukon and Alaska, and Significance in the Evolution of Northern Laurentia

Lithosphere ◽  
2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Karol Faehnrich ◽  
William C. McClelland ◽  
Maurice Colpron ◽  
Charlotte L. Nutt ◽  
Rebecca S. Miller ◽  
...  
Keyword(s):  
Shear Zone ◽  
Detrital Zircon ◽  
Geological Mapping ◽  
The Arctic ◽  
North Slope ◽  
Northern Margin ◽  
New Name ◽  
The North ◽  
Stratigraphic Architecture ◽  
Mississippian Rocks

Abstract The origin and displacement history of terranes emplaced along the northern margin of North America remain contentious. One of these terranes is the North Slope subterrane of the Arctic Alaska-Chukotka microplate, which is separated from the northwestern margin of Laurentia (Yukon block) by the Porcupine Shear Zone of Alaska and Yukon. Here, we present new field observations, geological mapping, detrital zircon U-Pb geochronology, and sedimentary/igneous geochemistry to elucidate the stratigraphic architecture of deformed pre-Mississippian rocks exposed within the Porcupine Shear Zone, which we distinguish herein as the newly defined Ch’oodeenjìk succession. The oldest rocks in the Ch’oodeenjìk succession consist of siliciclastic strata of the Lahchah and Sunaghun formations (new names), which yield detrital zircon U-Pb age populations of ca. 1050-1250, 1350-1450, 1600-1650, and 2500-2800 Ma (n =800). This succession is overlain by chert-bearing dolostone and limestone of the Caribou Bar formation (new name) that contains vase-shaped microfossils and yields carbonate carbon (δ13Ccarb) and strontium (87Sr/86Sr) isotopic data that range from ca. -3‰ to +3‰ and 0.70636 to 0.70714, respectively. These data suggest that Lahchah, Sunaghun, and Caribou Bar formations are late Tonian in age. These Neoproterozoic rocks are intruded by Late Devonian (Frasnian-Famennian) felsic plutons and mafic dikes, one of which yielded a sensitive high-resolution ion microprobe-reverse geometry (SHRIMP-RG) U-Pb age of 380 ± 4 Ma. Neoproterozoic strata of the Ch’oodeenjìk succession are also unconformably overlain by Upper Devonian-Carboniferous (?) siliciclastic rocks of the Darcy Creek formation (new name), which yields detrital zircon populations of ca. 365–385, 420-470 and 625-835 Ma, in addition to Proterozoic age populations similar to the underlying Tonian strata. Together, these new stratigraphic, geochronological, geochemical, and micropaleontological data indicate that pre-Mississippian rocks exposed within the Porcupine Shear Zone most likely represent a peri-Laurentian crustal fragment that differs from the adjacent Yukon block and North Slope subterrane; thus, the Porcupine Shear Zone represents a fundamental tectonic boundary separating autochthonous Laurentia from various accreted peri-Laurentian crustal fragments.

A detrital zircon test of large-scale terrane displacement along the Arctic margin of North America

Geology ◽  
2021 ◽  
Author(s):  
Timothy M. Gibson ◽  
Karol Faehnrich ◽  
James F. Busch ◽  
William C. McClelland ◽  
Mark D. Schmitz ◽  
...  
Keyword(s):  
North America ◽  
Detrital Zircon ◽  
Large Scale ◽  
Small Sample ◽  
The Arctic ◽  
North Slope ◽  
The North ◽  
Arctic Alaska ◽  
Laurentian Margin ◽  
Small Sample Sizes

Detrital zircon U-Pb geochronology is one of the most common methods used to constrain the provenance of ancient sedimentary systems. Yet, its efficacy for precisely constraining paleogeographic reconstructions is often complicated by geological, analytical, and statistical uncertainties. To test the utility of this technique for reconstructing complex, margin-parallel terrane displacements, we compiled new and previously published U-Pb detrital zircon data (n = 7924; 70 samples) from Neoproterozoic–Cambrian marine sandstone-bearing units across the Porcupine shear zone of northern Yukon and Alaska, which separates the North Slope subterrane of Arctic Alaska from northwestern Laurentia (Yukon block). Contrasting tectonic models for the North Slope subterrane indicate it originated either near its current position as an autochthonous continuation of the Yukon block or from a position adjacent to the northeastern Laurentian margin prior to >1000 km of Paleozoic–Mesozoic translation. Our statistical results demonstrate that zircon U-Pb age distributions from the North Slope subterrane are consistently distinct from the Yukon block, thereby supporting a model of continent-scale strike-slip displacement along the Arctic margin of North America. Further examination of this dataset highlights important pitfalls associated with common methodological approaches using small sample sizes and reveals challenges in relying solely on detrital zircon age spectra for testing models of terranes displaced along the same continental margin from which they originated. Nevertheless, large-n detrital zircon datasets interpreted within a robust geologic framework can be effective for evaluating translation across complex tectonic boundaries.

Exploration history and place names of northern East Greenland

1969 ◽  
Vol 21 ◽  
pp. 1-368 ◽  
Author(s):  
Anthony K. Higgins
Keyword(s):  
20Th Century ◽  
19Th Century ◽  
Geological Mapping ◽  
Geological Survey ◽  
The Arctic ◽  
Place Names ◽  
East Greenland ◽  
New Name ◽  
Systematic Compilation

The first recorded landing by Europeans on the coast of northern East Greenland (north of 69°N) was that of William Scoresby Jr., a British whaler, in 1822. This volume includes a chronological summary of the pioneer 19th century exploration voyages made by British, Danish, Norwegian, Swedish, French and German expeditions – all of whom reported that the region had previously been occupied by the Inuit or Eskimo; also included are brief outlines of the increasing number of government and privately sponsored expeditions throughout the 20th century, whose objectives included cartography, geology, zoology, botany, trapping and the ascent of the highest mountain summits. In 1934 the Place Name Committee for Greenland was established, the tasks of which included a review of all place names hitherto recorded on published maps of Greenland, their formal adoption in danicised form, and the approval or rejection of new name proposals. In northern East Greenland, by far the largest numbers of new place names were those proposed by scientists associated with Lauge Koch's geological expeditions that lasted from 1926 until 1958. This volume records the location and origin of more than 3000 officially approved place names as well as about 2650 unapproved names. The author's interest in the exploration history and place names of northern East Greenland started in 1968, when the Geological Survey of Greenland initiated a major five-year geological mapping programme in the Scoresby Sund region. Systematic compilation of names began about 1970, initially with the names given by William Scoresby Jr., and subsequently broadened in scope to include the names proposed by all expeditions to northern East Greenland. The author has participated in 16 summer mapping expeditions with the Survey to northern East Greenland. Publication of this volume represents the culmination of a lifetime working in the Arctic.

scholarly journals The influence of local oil exploration and regional wildfires on summer 2015 aerosol over the North Slope of Alaska

2018 ◽  
Vol 18 (2) ◽  
pp. 555-570 ◽  
Author(s):  
Jessie M. Creamean ◽  
Maximilian Maahn ◽  
Gijs de Boer ◽  
Allison McComiskey ◽  
Arthur J. Sedlacek ◽  
...  
Keyword(s):  
Cloud Microphysics ◽  
Department Of Energy ◽  
The Arctic ◽  
North Slope ◽  
The North ◽  
The Us ◽  
Range Transport ◽  
North Slope Of Alaska ◽  
Atmospheric Radiation Measurement ◽  
Arctic Atmosphere

Abstract. The Arctic is warming at an alarming rate, yet the processes that contribute to the enhanced warming are not well understood. Arctic aerosols have been targeted in studies for decades due to their consequential impacts on the energy budget, both directly and indirectly through their ability to modulate cloud microphysics. Even with the breadth of knowledge afforded from these previous studies, aerosols and their effects remain poorly quantified, especially in the rapidly changing Arctic. Additionally, many previous studies involved use of ground-based measurements, and due to the frequent stratified nature of the Arctic atmosphere, brings into question the representativeness of these datasets aloft. Here, we report on airborne observations from the US Department of Energy Atmospheric Radiation Measurement (ARM) program's Fifth Airborne Carbon Measurements (ACME-V) field campaign along the North Slope of Alaska during the summer of 2015. Contrary to previous evidence that the Alaskan Arctic summertime air is relatively pristine, we show how local oil extraction activities, 2015's central Alaskan wildfires, and, to a lesser extent, long-range transport introduce aerosols and trace gases higher in concentration than previously reported in Arctic haze measurements to the North Slope. Although these sources were either episodic or localized, they serve as abundant aerosol sources that have the potential to impact a larger spatial scale after emission.

Outreach and disseminations activities in North Slope of Alaska: how to build trust between local communities and arctic researchers

2020 ◽  
Author(s):  
Kaare Sikuaq Erickson ◽  
Donatella Zona ◽  
Marco Montemayor ◽  
Walter Oechel ◽  
Terenzio Zenone
Keyword(s):  
Common Ground ◽  
Local Community ◽  
Local Communities ◽  
The Arctic ◽  
North Slope ◽  
Science Fair ◽  
Methane Cycle ◽  
The North ◽  
North Slope Of Alaska ◽  
The University

<p>The Alaskan Ukpeaġvik Iñupiat Corporation (UIC) is promoting and financilally supporting, with the contribution of the US National Science Foundation (NSF) and local organizations, outreach and dissemination events, in the form of science fair for the local communities in North Slope of Alaska. The science fair is part of a larger effort by UIC Science to bring coordination and collaboration to science outreach and engagement efforts across Arctic Alaska. The purpose is to provide a positive space for Arctic researchers and Arctic residents to meet, eat with each other, spend time, and to inspire the youth of the Arctic by providing fun and educational activities that are based in science and traditional knowledge. The Science Fair 2019 hosted by the Barrow Arctic Research Center (BARC) included three days of youth and family-friendly activities related to “Inupiat Knowledge about Plants” led by the College Inupiat Studies Department, “Eco-chains Activity” hosted by the North Slope Borough Office of Emergency Management, “Big Little World: Bugs Plants, and Microscopes” hosted by the National Ecological Observatory Network, “Microplastics in the Arctic” hosted by the North Slope Borough Department of Wildlife Management, “BARC Scavenger Hunt” hosted by UIC Science, “Our Role in the Carbon and Methane Cycle” hosted by the University of Texas El Paso (UTEP) and San Diego State University, and “How Permafrost Works” hosted by the University of Alaska, Fairbanks, Geophysical Institute. Each day hundreds of students, from both the local community and the science community came together to take part in mutually beneficial engagement: students from Utqiaġvik were excited about science and now know of the realistic and fulfilling careers in research that takes place in their backyard. The Utqiaġvik community members and elders now have a better idea of the breadth of research that takes place in and near their home. The locals, especially the elders, are very concerned about the drastic changes in our environment: scientists share these concerns, and the discussions during the fair was a chance to recognize this common ground. Breaking the ice between Arctic researchers and residents can lead to endless opportunities for collaboration, sharing ideas, and even lifelong friendships.</p><p> </p><p> </p>

scholarly journals Planning Oil Spill Response Tactics for Offshore Production Islands

1999 ◽  
Vol 1999 (1) ◽  
pp. 1163-1166
Author(s):  
Michael Bronson ◽  
Thomas Chappie ◽  
Larry Dietrick ◽  
Ronald Hocking ◽  
James McHale
Keyword(s):  
Oil Spill ◽  
Oil Recovery ◽  
Oil Production ◽  
Open Water ◽  
Regulatory Approval ◽  
The Arctic ◽  
North Slope ◽  
The North ◽  
Offshore Production ◽  
Offshore Oil Production

ABSTRACT In anticipation of the Beaufort Sea's first two offshore production islands, Alaska's North Slope oil producers recently expanded their oil spill recovery tactical plans and equipment. To seek regulatory approval for offshore oil production, industry responders joined agency regulators and made plans to clean up as much as 225,000 barrels of oil from potential blowouts over 15 days. Response technicians are configuring new and existing skimmers, vessels, and barges on the North Slope to implement those planning standards. This paper outlines the oil spill tactical plans and equipment that Alaska's North Slope oil industry recently assembled in seeking regulatory approval for the first offshore production islands in the Arctic. The operators of North America's largest oil fields are beginning the first production from oil wells separated from roads and most spill response vessels. For example, the new Badami production pad lies on the Arctic coast more than 25 miles from the Prudhoe Bay facilities, across river courses and roadless tundra. Eight miles of ice-infested sea will separate the proposed Northstar and Liberty production islands from response vessel berths. The new fields regularly experience waves, cold, and ice invasions that constrain oil recovery efforts. Yet regulatory approval to begin oil production requires that the industry have plans and equipment to clean up all the oil that may enter open water, even from the largest spills, within 72 hours.

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