Uplift and exhumation in Haida Gwaii driven by terrane translation and transpression along the southern Queen Charlotte fault, Canada

Geology ◽  
2020 ◽  
Vol 48 (9) ◽  
pp. 908-912
Author(s):  
Philip Schoettle-Greene ◽  
Alison R. Duvall ◽  
Ann Blythe ◽  
Eric Morley ◽  
William Matthews ◽  
...  
Keyword(s):  
North America ◽  
North American ◽  
North American Plate ◽  
Cascadia Subduction Zone ◽  
Haida Gwaii ◽  
Crustal Shortening ◽  
Basin Inversion ◽  
Subduction Initiation ◽  
The North ◽  
The Pacific

Abstract The mountainous archipelago of Haida Gwaii abuts the transpressive Pacific–North American plate margin north of the Cascadia subduction zone (northwestern North America). Topography on Haida Gwaii has been attributed to either dynamic uplift supported by subduction initiation or crustal shortening driven by shear adjacent the plate-bounding Queen Charlotte fault. In order to resolve how intraplate strain is accommodated, we obtained thermochronometry data from 20 bedrock samples on Haida Gwaii, including zircon (U-Th)/He, apatite (U-Th-Sm)/He, and apatite fission-track dates. With dates ranging from 5 to 60 Ma, we interpret exhumation rates increasing in proximity to the Queen Charlotte fault and leading to a maximum of 6 km of exhumation since 20 Ma. The onset of exhumation significantly predates the purported initiation of subduction, precluding a direct relationship between subduction initiation and the development of topography in the archipelago. Instead, exhumation onset correlates with passage of the Yakutat terrane, suggesting that North America was deformed and Haida Gwaii uplifted during terrane translation. Steady or slightly decreasing exhumation rate since the Miocene is at odds with estimated increases to intraplate convergence over this time, ruling out crustal shortening in Haida Gwaii as the only response to transpression between North America and the Pacific. From this, we conclude that plate convergence is accommodated through basin inversion and internal shortening in the North American and Pacific plates as well as potential underthrusting of the Pacific plate beneath North America.

scholarly journals Intraseasonal and Interannual Variability in North American Storm Tracks and Its Relationship to Equatorial Pacific Variability

2013 ◽  
Vol 141 (10) ◽  
pp. 3610-3625 ◽  
Author(s):  
Kevin M. Grise ◽  
Seok-Woo Son ◽  
John R. Gyakum
Keyword(s):  
North America ◽  
Interannual Variability ◽  
North American ◽  
Southern Oscillation ◽  
Extratropical Cyclones ◽  
The North ◽  
The Pacific ◽  
Cyclone Tracks ◽  
Lagrangian Tracking ◽  
The North Atlantic Oscillation

Abstract Extratropical cyclones play a principal role in wintertime precipitation and severe weather over North America. On average, the greatest number of cyclones track 1) from the lee of the Rocky Mountains eastward across the Great Lakes and 2) over the Gulf Stream along the eastern coastline of North America. However, the cyclone tracks are highly variable within individual winters and between winter seasons. In this study, the authors apply a Lagrangian tracking algorithm to examine variability in extratropical cyclone tracks over North America during winter. A series of methodological criteria is used to isolate cyclone development and decay regions and to account for the elevated topography over western North America. The results confirm the signatures of four climate phenomena in the intraseasonal and interannual variability in North American cyclone tracks: the North Atlantic Oscillation (NAO), the El Niño–Southern Oscillation (ENSO), the Pacific–North American pattern (PNA), and the Madden–Julian oscillation (MJO). Similar signatures are found using Eulerian bandpass-filtered eddy variances. Variability in the number of extratropical cyclones at most locations in North America is linked to fluctuations in Rossby wave trains extending from the central tropical Pacific Ocean. Only over the far northeastern United States and northeastern Canada is cyclone variability strongly linked to the NAO. The results suggest that Pacific sector variability (ENSO, PNA, and MJO) is a key contributor to intraseasonal and interannual variability in the frequency of extratropical cyclones at most locations across North America.

scholarly journals Possibility of recovery of slip deficit rate between the North American plate and the Pacific plate off Sanriku, northeast Japan

2007 ◽  
Vol 34 (20) ◽  
Author(s):  
Shinzaburo Ozawa ◽  
Hisashi Suito ◽  
Takuya Nishimura ◽  
Mikio Tobita ◽  
Hiroshi Munekane
Keyword(s):  
North American ◽  
Pacific Plate ◽  
North American Plate ◽  
The North ◽  
Slip Deficit ◽  
The Pacific ◽  
Off Sanriku

scholarly journals A new species of Placiphorella (Polyplacophora: Mopaliidae) from the North American Pacific coast

The Festivus ◽  
2019 ◽  
Vol 51 (2) ◽  
pp. 103-107
Author(s):  
Roger Clark
Keyword(s):  
New Species ◽  
North America ◽  
North American ◽  
Deep Sea ◽  
Pacific Coast ◽  
The North ◽  
The Pacific ◽  
A New Species

A new deep-sea chiton of the genus Placiphorella Dall, 1879, Placiporella laurae n. sp. is described from the Pacific coast of North America. It is compared with its congener Placiphorella pacifica Berry, 1919, from which it differs primarily by having granular valves, lacking false beaks, a papillose girdle, and the characteristics of its girdle spicules

scholarly journals North American Winter Dipole: Observed and Simulated Changes in Circulations

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 793 ◽  
Author(s):  
Yu-Tang Chien ◽  
S.-Y. Simon Wang ◽  
Yoshimitsu Chikamoto ◽  
Steve L. Voelker ◽  
Jonathan D. D. Meyer ◽  
...  
Keyword(s):  
North America ◽  
North American ◽  
Large Scale ◽  
Climate Model ◽  
Model Simulations ◽  
The North ◽  
Weather Events ◽  
The Pacific ◽  
Climate Model Simulations ◽  
Northwestern North America

In recent years, a pair of large-scale circulation patterns consisting of an anomalous ridge over northwestern North America and trough over northeastern North America was found to accompany extreme winter weather events such as the 2013–2015 California drought and eastern U.S. cold outbreaks. Referred to as the North American winter dipole (NAWD), previous studies have found both a marked natural variability and a warming-induced amplification trend in the NAWD. In this study, we utilized multiple global reanalysis datasets and existing climate model simulations to examine the variability of the winter planetary wave patterns over North America and to better understand how it is likely to change in the future. We compared between pre- and post-1980 periods to identify changes to the circulation variations based on empirical analysis. It was found that the leading pattern of the winter planetary waves has changed, from the Pacific–North America (PNA) mode to a spatially shifted mode such as NAWD. Further, the potential influence of global warming on NAWD was examined using multiple climate model simulations.

scholarly journals Which MJO Events Affect North American Temperatures?

2013 ◽  
Vol 141 (11) ◽  
pp. 3840-3850 ◽  
Author(s):  
Carl J. Schreck ◽  
Jason M. Cordeira ◽  
David Margolin
Keyword(s):  
North America ◽  
North American ◽  
North Pacific ◽  
Wave Breaking ◽  
La Niña ◽  
Teleconnection Patterns ◽  
The North ◽  
La Nina ◽  
The Pacific ◽  
The North Pacific

Abstract Tropical convection from the Madden–Julian oscillation (MJO) excites and amplifies extratropical Rossby waves around the globe. This forcing is reflected in teleconnection patterns like the Pacific–North American (PNA) pattern, and it can ultimately result in temperature anomalies over North America. Previous studies have not explored whether the extratropical response might vary from one MJO event to another. This study proposes a new index, the multivariate PNA (MVP), to identify variations in the extratropical waveguide over the North Pacific and North America that might affect the response to the MJO. The MVP is the first combined EOF of 20–100-day OLR, 850-hPa streamfunction, and 200-hPa streamfunction over the North Pacific and North America. The North American temperature patterns that follow each phase of the MJO change with the sign of the MVP. For example, real-time multivariate MJO (RMM) phase 5 usually leads to warm anomalies over eastern North America. This relationship was only found when the MVP was negative, and it was not associated with El Niño or La Niña. RMM phase 8, on the other hand, usually leads to cold anomalies. Those anomalies only occur if the MVP is positive, which happens somewhat more frequently during La Niña years. Composite analyses based on combinations of the MJO and the MVP show that variability in the Pacific jet and its associated wave breaking play a key role in determining whether and how the MJO affects North American temperatures.

Piracy in Colonial North America

2020 ◽  
Author(s):  
Mark G. Hanna
Keyword(s):  
North America ◽  
New England ◽  
North American ◽  
18Th Century ◽  
Historical Narrative ◽  
British North America ◽  
American Colonies ◽  
The North ◽  
The Pacific ◽  
British North American

Historians of colonial British North America have largely relegated piracy to the marginalia of the broad historical narrative from settlement to revolution. However, piracy and unregulated privateering played a pivotal role in the development of every English community along the eastern seaboard from the Carolinas to New England. Although many pirates originated in the British North American colonies and represented a diverse social spectrum, they were not supported and protected in these port communities by some underclass or proto-proletariat but by the highest echelons of colonial society, especially by colonial governors, merchants, and even ministers. Sea marauding in its multiple forms helped shape the economic, legal, political, religious, and cultural worlds of colonial America. The illicit market that brought longed-for bullion, slaves, and luxury goods integrated British North American communities with the Caribbean, West Africa, and the Pacific and Indian Oceans throughout the 17th century. Attempts to curb the support of sea marauding at the turn of the 18th century exposed sometimes violent divisions between local merchant interests and royal officials currying favor back in England, leading to debates over the protection of English liberties across the Atlantic. When the North American colonies finally closed their ports to English pirates during the years following the Treaty of Utrecht (1713), it sparked a brief yet dramatic turn of events where English marauders preyed upon the shipping belonging to their former “nests.” During the 18th century, colonial communities began to actively support a more regulated form of privateering against agreed upon enemies that would become a hallmark of patriot maritime warfare during the American Revolution.

Eriosomatine aphids (Hemiptera: Aphididae: Eriosomatinae) associated with moss and roots of conifer and willow in forests of the Pacific Northwest of North America

2012 ◽  
Vol 144 (4) ◽  
pp. 555-576 ◽  
Author(s):  
K.S. Pike ◽  
G. Graf ◽  
R.G. Foottit ◽  
H.E.L. Maw ◽  
C. von Dohlen ◽  
...  
Keyword(s):  
North America ◽  
Pacific Northwest ◽  
North American ◽  
Deoxyribonucleic Acid ◽  
Sequence Matching ◽  
The North ◽  
The Pacific ◽  
First Time

AbstractApterous adult morphs of eriosomatine aphids associated with moss (Bryophyta) and/or roots of conifer (Pinaceae) or willow (Salix Linnaeus (Salicaceae)) in forests of the North American Pacific Northwest including Alaska are described, illustrated, and keyed. In total, seven species (Clydesmithia canadensis Danielsson, Melaphis rhois (Fitch) (moss only feeder), Pachypappa rosettei (Maxson), Pachypappa sacculi (Gillette), Prociphilus americanus (Walker) (fir root only feeder), Prociphilus xylostei (De Geer), and Thecabius populimonilis (Riley)) are characterised from their secondary host habitats. Secondary host forms of C. canadensis and T. populimonilis are described for the first time. The morphotypes from the secondary hosts were confirmed through deoxyribonucleic acid sequence matching with those from the primary hosts.

scholarly journals Ammonites from the Upper Cretaceous of West Greenland

1965 ◽  
Vol 56 ◽  
pp. 1-192
Author(s):  
T Birkelund
Keyword(s):  
North America ◽  
North American ◽  
Upper Cretaceous ◽  
The Arctic ◽  
Arctic Seas ◽  
West Greenland ◽  
The North ◽  
Type Area ◽  
The Pacific ◽  
Lower Campanian

Ammonites from Nûgssuaq and Svartenhuk, belonging to the genera Hypophylloceras, Saghalinites, Pseudophyllites, Baculites, Diplomoceras, Scaphites, Clioscaphites, Haresiceras and Borissjakoceras, are described. Baculites and Scaphites are richly represented, and the material provides a basis for evaluating the subgenera Hoploscaphites and Discoscaphites. The ontogeny and the phylogeny of most of the genera are discussed and juvenile stages of Saghalinites and Scaphites described. Eleven new species and three new subspecies are introduced. The stratigraphical, palaeogeographical and palaeoecological aspeets of the ammonite assemblages are considered, and a discussion of sexual dimorphism in Scaphites is given. The presence of 12 biozones from the Upper Turonian?, Coniacian, Santonian, Campanian and Maastrichtian is demonstrated. The stratigraphical correlation of European and North American Upper Cretaceous deposits is discussed and the West Greenland zones are correlated with North American and European ammonite zones. All the Upper Turonian ?-Santonian species have affinities with species endemic to the Western Interior of North America. One of the genera, Clioscaphites from the Santonian, occur only within that area. The Campanian scaphites and baculites are at first mostly like species from the Interior of North America, later, in the Upper Campanian, European affinities are more prominent. Haresiceras from the Lower Campanian is endemic to the Western Interior of North America. The Maastrichtian scaphites and baculites are closely related to endemic species from the Interior of North America, principally from the Fox Hills Formation of the type area. Hypophylloceras, Saghalinites and Pseudophyllites from the Campanian-Maastrichtian have Indo-Pacific relations and Diplomoceras may be related to European forms. The ammonites, together with the belemnites and inoceramids from the area, so far as they are identified, show that a sea-way to the north, through the Arctic Seas, conneeted this area with the Interior of North America from the Upper Turonian or Coniacian to the Maastrichtian. The area apparently was also connected with Europe by a sea-way during that part of the Upper Cretaceous. The occurrence of ammonites with Indo-Pacific affinities may further indicate the presence of a northern sea-way between the Pacific and the Arctic Seas during parts of the Campanian-Maastrichtian interval.Scaphites is given. The presence of 12 biozones from the Upper Turonian?, Coniacian, Santonian, Campanian and Maastrichtian is demonstrated. The stratigraphical correlation of European and North American Upper Cretaceous deposits is discussed and the West Greenland zones are correlated with North American and European ammonite zones. All the Upper Turonian ?-Santonian species have affinities with species endemic to the Western Interior of North America. One of the genera, Clioscaphites from the Santonian, occur only within that area. The Campanian scaphites and baculites are at first mostly like species from the Interior of North America, later, in the Upper Campanian, European affinities are more prominent. Haresiceras from the Lower Campanian is endemic to the Western Interior of North America. The Maastrichtian scaphites and baculites are closely related to endemic species from the Interior of North America, principally from the Fox Hills Formation of the type area. Hypophylloceras, Saghalinites and Pseudophyllites from the Campanian-Maastrichtian have Indo-Pacific relations and Diplomoceras may be related to European forms. The ammonites, together with the belemnites and inoceramids from the area, so far as they are identified, show that a sea-way to the north, through the Arctic Seas, conneeted this area with the Interior of North America from the Upper Turonian or Coniacian to the Maastrichtian. The area apparently was also connected with Europe by a sea-way during that part of the Upper Cretaceous. The occurrence of ammonites with Indo-Pacific affinities may further indicate the presence of a northern sea-way between the Pacific and the Arctic Seas during parts of the Campanian-Maastrichtian interval.

Reinterpretation of the North American apparent polar wander curve for the interval 800–1500 Ma

1980 ◽  
Vol 17 (9) ◽  
pp. 1229-1235 ◽  
Author(s):  
Glenn W. Berger ◽  
Derek York
Keyword(s):  
North America ◽  
North American ◽  
Baltic Shield ◽  
Drift Rate ◽  
El Paso ◽  
Continental Drift ◽  
Polar Wander ◽  
The North ◽  
The Pacific ◽  
The Baltic

We have reviewed the geochronology of rocks having paleopoles in the interval 800–1500 Ma from North America, Greenland, and the Baltic Shield. The present uncertainties in the acquisition times of the remanent magnitizations allow the construction of a simplified apparent polar wander curve for North America that incorporates Sveconorwegian paleopoles in a Grenville Loop, and that places poles from the El Paso, Stoer Group, and Aillik Bay rocks on the Logan Loop. Furthermore, the sense of motion through poles older than ~ 1.3 Ga is reversed to permit the shortest connection to poles older than 1.6 Ga. As well, the timing and shape of the Hadrynian Track are modified so that it begins in the Atlantic hemisphere at ~ 800 Ma and terminates in the Pacific at ~ 650 Ma, representing a minimum average continental drift rate of ~ 10 cm/year for this interval.

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