TY - JOUR
T1 - High-resolution temporal and stratigraphic record of Siletzia's accretion and triple junction migration from nonmarine sedimentary basins in central and western Washington
AU - Eddy, Michael P.
AU - Bowring, Samuel A.
AU - Umhoefer, Paul J.
AU - Miller, Robert B.
AU - McLean, Noah M.
AU - Donaghy, Erin E.
N1 - Funding Information:
We thank Jim Evans and Joe Vance for sharing the location of tuffs within the studied sedimentary sequences, and E. Barry, T. LaCasse, E. Shorin, Y. Park, and J. Pu for field and laboratory assistance. Funding for this project was provided by National Science Foundation grants EAR-0510591 and EAR-1118883 to Bowring, EAR-0511062 and EAR-1119358 to Miller, and EAR-1119063 to Umhoefer. This manuscript benefited from reviews by S.T. Johnston, D.J. Thorkelson, and R.E. Wells.
Publisher Copyright:
© 2015 Geological Society of America.
PY - 2016
Y1 - 2016
N2 - The presence of early Eocene neartrench magmatism in western Washington and southern British Columbia has led to speculation that this area experienced ridge-trench interaction during that time. However, the effects of this process as they are preserved in other parts of the geologic record are poorly known. We present highprecision U-Pb zircon geochronology from Paleogene nonmarine sedimentary and volcanic sequences in central and western Washington that preserve a record of tectonic events between ca. 60 and 45 Ma. The data reveal that the Swauk, Chuckanut, and Manastash Formations formed a nonmarine sedimentary basin along the North American margin between ≤59.9 and 51.3 Ma. This basin experienced significant disruption that culminated in basinwide deformation, uplift, and partial erosion during accretion of the Siletzia terrane between 51.3 and 49.9 Ma. Immediately following accretion, dextral strike-slip faulting began, or accelerated, on the Darrington-Devil's Mountain, Entiat, Leavenworth, Eagle Creek, and Straight Creek-Fraser fault zones between 50 and 46 Ma. During this time, the Chumstick Formation was deposited in a strike-slip basin coeval with near-trench magmatism. Faulting continued on the Entiat, Eagle Creek, and Leavenworth faults until a regional sedimentary basin was reestablished ≤45.9 Ma, and may have continued on the Straight Creek-Fraser fault until 35-30 Ma. This record of basin disruption, volcanism, and strike-slip faulting is consistent with ridgetrench interaction and supports the presence of an oceanic spreading ridge at this latitude along the North American margin during the early Eocene.
AB - The presence of early Eocene neartrench magmatism in western Washington and southern British Columbia has led to speculation that this area experienced ridge-trench interaction during that time. However, the effects of this process as they are preserved in other parts of the geologic record are poorly known. We present highprecision U-Pb zircon geochronology from Paleogene nonmarine sedimentary and volcanic sequences in central and western Washington that preserve a record of tectonic events between ca. 60 and 45 Ma. The data reveal that the Swauk, Chuckanut, and Manastash Formations formed a nonmarine sedimentary basin along the North American margin between ≤59.9 and 51.3 Ma. This basin experienced significant disruption that culminated in basinwide deformation, uplift, and partial erosion during accretion of the Siletzia terrane between 51.3 and 49.9 Ma. Immediately following accretion, dextral strike-slip faulting began, or accelerated, on the Darrington-Devil's Mountain, Entiat, Leavenworth, Eagle Creek, and Straight Creek-Fraser fault zones between 50 and 46 Ma. During this time, the Chumstick Formation was deposited in a strike-slip basin coeval with near-trench magmatism. Faulting continued on the Entiat, Eagle Creek, and Leavenworth faults until a regional sedimentary basin was reestablished ≤45.9 Ma, and may have continued on the Straight Creek-Fraser fault until 35-30 Ma. This record of basin disruption, volcanism, and strike-slip faulting is consistent with ridgetrench interaction and supports the presence of an oceanic spreading ridge at this latitude along the North American margin during the early Eocene.
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U2 - 10.1130/B31335.1
DO - 10.1130/B31335.1
M3 - Article
AN - SCOPUS:84960540857
SN - 0016-7606
VL - 128
SP - 425
EP - 441
JO - Bulletin of the Geological Society of America
JF - Bulletin of the Geological Society of America
IS - 3-4
ER -