From Terranes to Terrains: Geologic Field Guides on the Construction and Destruction of the Pacific Northwest

2021 ◽  
Keyword(s):  
Pacific Northwest ◽  
Hot Spot ◽  
Flood Basalt ◽  
Field Trips ◽  
Ice Age ◽  
Basin And Range Province ◽  
Western Margin ◽  
Field Guides ◽  
The Pacific ◽  
The Rich

The eight field trips in this volume, associated with GSA Connects 2021 held in Portland, Oregon, USA, reflect the rich and varied geological legacy of the Pacific Northwest. The western margin of North America has had a complex subduction and transform history throughout the Phanerozoic, building a collage of terranes. The terrain has been modified by Cenozoic sedimentation, magmatism, and faulting related to Cascadia subduction, passage of the Yellowstone hot spot, and north and westward propagation of the Basin and Range province. The youngest flood basalt province on Earth also inundated the landscape, while the mighty Columbia watershed kept pace with arc construction and funneled epic ice-age floods from the craton to the coast. Additional erosive processes such as landslides continue to shape this dynamic geological wonderland.

scholarly journals Igneous Rock Associations 27. Chalcophile and Platinum Group Elements in the Columbia River Basalt Group: A Model for Flood Basalt Lavas

2020 ◽  
Vol 47 (4) ◽  
pp. 187-214
Author(s):  
Stephen P. Reidel ◽  
D. Brent Barnett
Keyword(s):  
Pacific Northwest ◽  
Columbia River ◽  
Flood Basalt ◽  
Platinum Group Elements ◽  
Large Igneous Province ◽  
Chalcophile Elements ◽  
Columbia River Basalt ◽  
The Pacific ◽  
Platinum Group ◽  
Columbia River Basalt Group

The Columbia River Basalt Group is the youngest and best preserved continental Large Igneous Province on Earth. The 210,000 km3 of basaltic lavas were erupted between 16.6 and 5 Ma in the Pacific Northwest, USA. The peak of the eruptions occurred over a 700,000-year period when nearly 99% of the basalts consisting of the Steens, Imnaha, Picture Gorge, Grande Ronde and Wanapum Basalts were emplaced. In this study we examined the Platinum Group Elements (PGEs) Pt and Pd, and the chalcophile elements Cu and Zn in the Columbia River Basalt Group. The presence of Pt, Pd and Cu in the compositionally primitive Lower Steens, Imnaha and Picture Gorge Basalts suggests that the Columbia River Basalt Group magma was a fertile source for these elements. The PGEs are contained mainly in sulphides in the earliest formations based on their correlation with immiscible sulphides, sulphide minerals and chalcophile elements. Grande Ronde, Wanapum and Saddle Mountains Basalts are depleted in PGEs and chalcophile elements compared to earlier formations. Sulphur was saturated in many flows and much of it probably came from assimilation of cratonic rock from a thinned lithosphere. We propose a model where the presence or absence of PGEs and chalcophile elements results primarily from the interaction between an advancing plume head and the crust/lithosphere that it encountered. The early lavas erupted from a plume that had little interaction with the crust/lithosphere and were fertile. However, as the plume head advanced northward, it assimilated crustal/lithospheric material and PGE and chalcophile elements were depleted from the magma. What little PGE and chalcophile elements remained in the compositionally evolved and depleted Grande Ronde Basalt flows mainly were controlled by substitution in basalt minerals and not available for inclusion in sulphides.  

scholarly journals Hunter-gatherer complexity on the west coast of North America

Antiquity ◽  
1991 ◽  
Vol 65 (249) ◽  
pp. 921-923
Author(s):  
Hergert D. G. Maschner ◽  
Brian M. Fagan
Keyword(s):  
North America ◽  
Pacific Northwest ◽  
Social Relations ◽  
West Coast ◽  
Bering Strait ◽  
The West ◽  
Franz Boas ◽  
European Contact ◽  
The Pacific ◽  
The Rich

The west coast of North America encompasses some of the richest and most diverse maritime environments on earth. Even in their presentday impoverished state, they support major commercial fisheries, large whale migrations and dense sea mammal populations. From the earliest days of European exploration, visitors such as the redoubtable Captain James Cook commented on the rich culture of Pacific coast peoples (Beaglehole 1967). ‘Their life may be said to comprise a constant meal,’ remarked Spanish friar Pedro Fages of the Chumash peoples of the Santa Barbara Channel in southern California. At European contact, between the 16th and 18th centuries AD, the shores of the Bering Strait, the Pacific Northwest and parts of the California coast supported elaborate, sophisticated and sedentary huntergatherer peoples. These decimated and muchchanged societies still enjoyed elaborate ceremonials and intricate social relations as late as the late 19th and early 20th centuries, when pioneer anthropologists such as Franz Boas and John Harrington worked among them. From these researches have come classic stereotypes of west coast peoples as ‘complex huntergatherer societies’, some of which were organized in powerful chiefdoms. Peoples like the Tlingit, the Kwakiutl and the Chumash have become the epitome of complex huntergatherers in many archaeologists’ eyes.

Valley of the Willamette

Hoptopia ◽  
2016 ◽  
Author(s):  
Peter A. Kopp
Keyword(s):  
Nineteenth Century ◽  
Pacific Northwest ◽  
Ice Age ◽  
Willamette Valley ◽  
Commercial Agriculture ◽  
Wheat Production ◽  
The Pacific ◽  
First Peoples ◽  
Last Ice Age ◽  
Fort Vancouver

This chapter begins with an explanation of the geology, climate, ecosystems, and first peoples of Oregon’s Willamette Valley after the last ice age. It then explains how those factors contributed to success of commercial agriculture upon resettlement by Europeans in the nineteenth century. While hops had been grown Fort Vancouver as early as the 1830s, there is no record of them growing anywhere else in the Pacific Northwest. Instead, the Fort Vancouver and subsequently the Willamette Valley emerged as centers of livestock and wheat production by midcentury. The end of the chapter explains how the new residents transformed the Willamette Valley into a major center of agriculture in the Far West, and this ultimately helped set the stage for hop production.

Suitability of Natural Areas for Representing Ecological Change in the Pacific Northwest

2019 ◽  
Vol 39 (4) ◽  
pp. 452
Author(s):  
Margaret H. Massie ◽  
Todd M. Wilson ◽  
Anita T. Morzillo ◽  
Emilie B. Henderson
Keyword(s):  
Pacific Northwest ◽  
Ecological Change ◽  
Natural Areas ◽  
The Pacific
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