P-wave tomography of eastern North America: Evidence for mantle evolution from Archean to Phanerozoic, and modification during subsequent hot spot tectonism

2012 ◽  
Vol 117 (B12) ◽  
pp. n/a-n/a ◽  
Author(s):  
M. Villemaire ◽  
F. A. Darbyshire ◽  
I. D. Bastow
Keyword(s):  
North America ◽  
Hot Spot ◽  
P Wave ◽  
Eastern North America ◽  
Mantle Evolution ◽  
Wave Tomography

A comparison of Eastern North America and Coastal New England magma suites: implications for subcontinental mantle evolution and the broad-terrane hypothesis

2005 ◽  
Vol 42 (9) ◽  
pp. 1571-1587 ◽  
Author(s):  
Michael J Dorais ◽  
Matthew Harper ◽  
Susan Larson ◽  
Hendro Nugroho ◽  
Paul Richardson ◽  
...  
Keyword(s):  
North America ◽  
New England ◽  
Trace Element ◽  
Crustal Contamination ◽  
Flood Basalt ◽  
Incompatible Trace Element ◽  
Eastern North America ◽  
Mantle Evolution ◽  
Isotopic Compositions ◽  
Maritime Canada

New England and Maritime Canada host two major suites of Mesozoic diabase dykes. The oldest is the Coastal New England dykes that were emplaced between 225 and 230 Ma. These rocks are dominantly alkaline with trace element and isotopic compositions indicative of a high-238U/204Pb mantle (HIMU) source. The oldest of the ~200 Ma Mesozoic rift magmas is represented by the Talcott basalt of the Hartford basin and its feeder dykes. External to the basin is the compositionally equivalent Higganum dyke. The extension of the Higganum, the Onway dyke in New Hampshire, is identical in major and trace element and isotopic compositions indicating that the dyke system represented a feeder to flows of flood basalt proportions. The Talcott system rocks have some trace element similarities with arc basalts and have been interpreted as representing melts of a subduction zone modified mantle beneath the Laurentian- Gondwanan suture. Incompatible trace element ratios and Ba, Th, and U values are, however, unlike arc basalts and are more indicative of crustal contamination of the primary magma. The coastal New England magmas have oceanic island basalt signatures that are generally thought to represent plume-tail magmatism, which is antithetic to a plume-head origin for the younger eastern North America magmas. However, coastal New England rocks have the same trace element signatures as the alkaline rocks of the Loihi seamount, which represent the pre-shield stage to the voluminous tholeiitic magmatism in Hawaii.

Subsurface Shear Wave Velocity Characterization Using P-Wave Seismograms in Central and Eastern North America

2016 ◽  
Vol 32 (1) ◽  
pp. 143-169 ◽  
Author(s):  
Byungmin Kim ◽  
Youssef M. A. Hashash ◽  
Ellen M. Rathje ◽  
Jonathan P. Stewart ◽  
Sidao Ni ◽  
...  
Keyword(s):  
North America ◽  
Wave Velocity ◽  
P Wave ◽  
Motion Prediction ◽  
Eastern North America ◽  
Ground Motion Prediction ◽  
Profile Data ◽  
S Wave ◽  
Wave Velocities ◽  
Linear Relationships

The time-averaged shear ( S) wave velocity in the upper 30 meters of sediment ( V S30) is a widely used site parameter for ground motion prediction. When unavailable from measurements, as is often the case at accelerograph stations in Central and Eastern North America (CENA), V S30 is typically estimated from proxies. We propose an alternative for CENA based on a theoretical relationship between S-wave velocity and the ratio of radial to vertical components of the compressional ( P)-wave–dominated portion of the velocity time series. This method is applied to 31 CENA accelerograph sites having measured S-wave velocity profiles. Time-averaged S-wave velocities to depth z ( V SZ) from the proposed method agree well with those from measurements. We develop linear relationships between V SZ and V S30 using CENA S-wave velocity profile data. Values of V S30 established from the proposed method (including depth extrapolation) have lower dispersion relative to data ( σln V = 0.43) than do estimates from available CENA proxies.

scholarly journals Anticosti Island: a hot spot for Neospondylis upiformis (Coleoptera: Cerambycidae) in eastern Canada?

2018 ◽  
Vol 6 ◽  
pp. e25553
Author(s):  
Christian Hébert ◽  
Serge Laplante ◽  
Mario Fréchette ◽  
Luc Jobin
Keyword(s):  
North America ◽  
Hot Spot ◽  
Balsam Fir ◽  
Eastern North America ◽  
Insect Diversity ◽  
Longhorned Beetle ◽  
Eastern Canada ◽  
Old Growth ◽  
South Central ◽  
Anticosti Island

During an inventory of insect diversity on Anticosti Island in 1993, we caught unprecedented numbers of Neospondylisupiformis (Mannerheim), a longhorned beetle rarely observed in eastern North America. All specimens were caught using 12-funnel Lindgren traps baited with 95% ethanol and α-pinene. This longhorned beetle was captured again in 2007 on Anticosti with the same traps. Other than that, seven specimens of N.upiformis were caught elsewhere in Quebec between 1993 and 2015. Only 14 specimens were found in the 45 most important insect collections of the province, the most recent specimen dating back to 1964. At least 90% of the captures came from old-growth balsam fir stands of the south-central part of the island. Seasonal flight activity ranged from early June to late July, but adult captures peaked in early July. Results suggest that Anticosti Island might be a hot spot for N.upiformis in eastern North America, particularly in its south-central part where old-growth balsam fir forests still exist.

The Identification and Study of Indian Shell Middens in Eastern North America: 1643–1861

1986 ◽  
Vol 6 (3) ◽  
pp. 227-243 ◽  
Author(s):  
Andrew L. Christenson
Keyword(s):  
Nineteenth Century ◽  
Civil War ◽  
North America ◽  
East Coast ◽  
Eastern North America ◽  
Shell Midden ◽  
Shell Middens ◽  
Work Done

Although the interest in shell middens in North America is often traced to reports of the discoveries in Danish kjoekkenmoeddings in the mid-nineteenth century, extensive shell midden studies were already occurring on the East Coast by that time. This article reviews selected examples of this early work done by geologists and naturalists, which served as a foundation for shell midden studies by archaeologists after the Civil War.

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