scholarly journals Cenozoic Relative Plate Motions Along the northeastern Pacific Margin and Their Association With Queen Charlotte area Tectonics and Volcanism

1991 ◽  
Author(s):  
R D Hyndman ◽  
T S Hamilton
Keyword(s):  
Plate Motions ◽  
Northeastern Pacific ◽  
Pacific Margin

The Pliensbachian ammonite Dayiceras dayiceroides and Early Jurassic paleogeography

1983 ◽  
Vol 20 (1) ◽  
pp. 86-91 ◽  
Author(s):  
Paul L. Smith
Keyword(s):  
British Columbia ◽  
Early Jurassic ◽  
Eastern Pacific ◽  
Western Tethys ◽  
Disjunct Population ◽  
Northeastern Pacific ◽  
Pacific Margin ◽  
Genetic Continuity ◽  
Central Atlantic ◽  
New Occurrences

Uptonia? dayiceroides Mouterde is placed in the genus Dayiceras and its age established as latest Jamesoni Zone to possibly earliest Domerian. The species is abundant and associated with faunas of Tethyan aspect along the northeastern Pacific margin. First occurrences in Oregon and Nevada and new occurrences in British Columbia are reported. Localities at apparently high paleolatitudes are attributed to post-early Pliensbachian transcurrent fault displacements. Genetic continuity with a disjunct population in Portugal is postulated via a central Atlantic seaway, here named the Hispanic Corridor, connecting the eastern Pacific and western Tethys Oceans. The existence of this corridor during the Pliensbachian is supported by several lines of independent paleobiogeographic evidence.

scholarly journals Diversity of bathyal macrofauna on the northeastern Pacific margin: the influence of methane seeps and oxygen minimum zones

2009 ◽  
Vol 31 (1) ◽  
pp. 94-110 ◽  
Author(s):  
Lisa A. Levin ◽  
Guillermo F. Mendoza ◽  
Jennifer P. Gonzalez ◽  
Andrew R. Thurber ◽  
Erik E. Cordes
Keyword(s):  
Methane Seeps ◽  
Oxygen Minimum Zones ◽  
Northeastern Pacific ◽  
Pacific Margin ◽  
Oxygen Minimum

Malacological insights into the marine ecology and changing climate of the late Pleistocene – early Holocene Queen Charlotte Islands archipelago, western Canada, and implications for early peoples

2003 ◽  
Vol 81 (4) ◽  
pp. 626-661 ◽  
Author(s):  
Renée Hetherington ◽  
Robert G.B Reid
Keyword(s):  
Short Interval ◽  
Marine Ecology ◽  
Bivalve Species ◽  
Queen Charlotte Islands ◽  
Northeastern Pacific ◽  
Pacific Margin ◽  
High Turbidity ◽  
Cold Hardy ◽  
Cordilleran Ice Sheet ◽  
Protothaca Staminea

The first intertidal species to colonize the Queen Charlotte Islands archipelago along the northeastern Pacific margin of Canada after the last glacial maximum (LGM) was Macoma nasuta at 13 210 ± 80 14C years BP. Prior to this time, molluscs were likely excluded where grounded ice extended from the 2 km thick Cordilleran ice sheet on mainland British Columbia. Low water temperatures, high sedimentation rates, high turbidity, dilution, and low primary productivity limited invertebrate colonization subsequent to the LGM, a period of rapid sea-level and climate change. As an adult, M. nasuta is a facultative deposit-suspension feeder that tolerates high turbidity and lowered salinity, and its pediveligers and early juveniles must also have been able to survive these conditions. Subsequently, in addition to M. nasuta, Macoma irus (inquinata), Saxidomus giganteus, Protothaca staminea, Protothaca tenerrima, Hiatella pholadis, Clinocardium nuttallii, and Mytilus trossulus constituted a typical intertidal bivalve assemblage. These findings are explained in terms of the physiology, feeding mechanisms, development, and sediment preferences of living molluscs. The disappearance of most bivalve species between ~11 000 and 10 000 14C years BP indicates the onset of a short interval of low sea-surface temperatures coincident with the Younger Dryas cooling event. Some cold-hardy species persisted, including Clinocardium californiense, Mya truncata, and Serripes groenlandicus. Bivalve species not previously reported as Pleistocene fossils were collected in sediments dating older than 10 000 14C years BP. They include Macoma incongrua, Musculus taylori, Mytilimeria nuttallii, and Tellina nuculoides. Fossil assemblages of intertidal molluscs are used to map ancient shorelines and indicate which species were available as a subsistence resource for early peoples from at least 13 210 ± 80 14C years BP. Intertidal food biomass densities may have reached present commercially harvested levels on southern Moresby Island by 8800 ± 70 14C years BP and on northern Graham Island by 8990 ± 50 14C years BP. When early peoples might have been migrating along the littoral zone, the molluscan productivity of the outer coast was much higher than it is at present.

Petrography and geochemistry of feldspathic and mafic sediments of the northeastern Pacific margin

1985 ◽  
Vol 76 (4) ◽  
pp. 411-449 ◽  
Author(s):  
Peter C. van de Kamp ◽  
Bernard Elgey Leake
Keyword(s):  
Sierra Nevada ◽  
Tectonic Setting ◽  
Potassium Feldspar ◽  
Igneous Rocks ◽  
Plate Tectonic ◽  
Late Mesozoic ◽  
Chemical Signatures ◽  
Clastic Sediments ◽  
Northeastern Pacific ◽  
Pacific Margin

ABSTRACTThis study attempts to ascertain whether the differing provenance sources and plate tectonic settings of deposition of clastic sediments and rocks can be identified by chemical means, thus opening the increased use of these rocks and their metamorphosed derivatives in plate tectonic modelling. Mineralogically immature feldspathic and mafic sands, muds, sandstones and shales from Mesozoic, Cenozoic and Holocene clastic deposits in California, Oregon, Alaska and Colorado have been both modally and chemically analysed providing a valuable data base (217 samples; 216 samples chemically analysed, many for 28 elements).There is significant upward chemical variation in the Great Valley sequence of California which mimics previously described petrographic variation and in turn reflects provenance changes with igneous episodes and erosional stripping of the Sierra Nevada in late Mesozoic time. Differing sandstone petrofacies result in varying chemical signatures and while the provenances of monomict sediments are easiest to identify, polymict sources involving granitoid or ophiolitic material can often be identified by potassium feldspar or Cr contents. The distinction of K which is derived from detrital potassium feldspar from K derived from detrital illite, micas or other sheet minerals, is best made by a Niggli al–alk plot against k. Mafic sandstones derived from mafic volcanic or plutonic rocks preserve essentially mafic igneous chemistry and could be possible parent sources of some amphibolites which grade into metasediments. The lithified erosion products of the Sierra Nevada calc-alkaline igneous rocks have higher Niggli al–alk and higher average Niggli si at any given mg value than the fresh igneous rocks enabling meta-arkoses to be distinguished from meta-igneous rocks.Applying previously published chemical criteria gives the actual plate tectonic setting of deposition of most of the sandstones studied. This suggests that the chemical composition of sandstones can yield much more information about the provenance and plate tectonic setting than hitherto recognised.

Occurrence of a squaloid shark (Chondrichthyes: Squaliformes) with the pinniped Allodesmus from the upper Miocene of Washington

1994 ◽  
Vol 68 (3) ◽  
pp. 680-684 ◽  
Author(s):  
Phillip K. Bigelow
Keyword(s):  
Cervical Vertebrae ◽  
Washington State ◽  
Matrix Blocks ◽  
Northeastern Pacific ◽  
The Matrix ◽  
Pacific Margin ◽  
The University ◽  
Relationship Of ◽  
A New Species ◽  
Tooth Marks

During preparation of a new species of Allodesmus from the Montesano Formation (UWBM 75640; presently being described by the writer) at the University of Washington Burke Memorial Museum in 1984, preparator Bev Witte found 14 monospecific elasmobranch teeth (UWBM 75641) in the matrix encasing the specimen. Most of the teeth were found in the matrix surrounding the cervical vertebrae; a few teeth were found near the skull (Figure 1). Unfortunately, the precise location of each tooth in relation to the pinniped skeleton was not recorded during their air-abrasive removal from the indurated matrix. It is known that the teeth were deposited no more than one or two centimeters from the skeleton. One of the matrix blocks freed from the pinniped still contains two teeth that line the inner surface of a mold of an unidentified Allodesmus bone. This is the first published occurrence of a shark from the Montesano Formation. The occurrence extends the range of Squalus occidentalis northward along the northeastern Pacific margin into Washington State, and it is also one of the highest biostratigraphic occurrences for this species. The discovery is additionally noteworthy because of the depositional relationship of the Allodesmus and Squalus, and because tooth marks occur on the Allodesmus skull. The occurrence therefore has taphonomic and paleoecological implications.

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