Stratigraphy and chronology of quaternary deposits of the Puget Lowland and Olympic Mountains of Washington and the Cascade Mountains of Washington and Oregon

Easterbrook, Don J.

doi:10.1016/0277-3791(86)90180-0

Cited by 31 publications

(22 citation statements)

References 93 publications

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“…Our study corroborates these findings and shows that the observed young AHe ages require a recent increase in exhumation rates from slower rates (< 0.2 km Myr −1 ) lasting from ∼ 7 until ∼ 2 Ma. Glaciation of the North American continent commenced at 2.7 Ma (Haug et al, 2005) and the oldest glacial deposits within the Olympics could be as old as 2 Ma (Easterbrook, 1986), overlapping our modeled increase in rates at ∼ 2 Ma. Due to the strong spatial variation of the Pleistocene equilibrium line altitude within the Olympic Mountains (Porter, 1964), glacial erosion likely also varied spatially, which could explain the different magnitude of the increase in exhumation rates suggested for the different samples.…”

Section: Temporal Variations In Exhumationsupporting

confidence: 82%

“…1c). This terrane represents a large oceanic plateau and extends from the southern tip of Vancouver Island to Oregon (Eddy et al, 2017;Phillips et al, 2017;Wells et al, 2014). The accretionary wedge of the subduction zone is exposed onshore within the Olympic Mountains ( Fig.…”

Section: Geology and Glacial History Of The Olympic Mountainsmentioning

confidence: 99%

“…1c), a major discontinuity traceable in seismic surveys (e.g., Clowes et al, 1987;Calvert et al, 2011). Minor sedimentary rocks of Eocene age (Eddy et al, 2017;Tabor and Cady, 1978) are contained within the Coast Range Terrane besides the predominant ∼ 50 Ma marine and subaerial basaltic rocks (Eddy et al, 2017). Exhumation of the range commenced at 18 Ma and since 14 Ma, the orogen is presumed to be in flux steady state (Batt et al, 2001;Brandon et al, 1998;Pazzaglia and Brandon, 2001).…”

Section: Geology and Glacial History Of The Olympic Mountainsmentioning

confidence: 99%

“…Volcanic activity after du Bray and John (2011). Tectonic and climatic events are (1) the start of exhumation of the Olympic Mountains (Brandon et al, 1998), (2) the onset of uplift of the Oregon Coast Range (McNeill et al, 2000), (3) rotation in the stress field (Priest, 1990), (4) faster uplift in the Oregon Coast Range (McNeill et al, 2000), (5) Pacific-wide plate reorganization (Wilson, 2002), (6) the onset of North American glaciation (Haug et al, 2005), (7) the onset of glaciation within the Olympic Mountains (Easterbrook, 1986), and (8) a change in the deformational style of the offshore accretionary wedge (Flueh et al, 1998). Convergence rate and angle from Doubrovine and Tarduno (2008).…”

Section: Pattern Of Exhumationmentioning

confidence: 99%

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How steady are steady-state mountain belts? A reexamination of the Olympic Mountains (Washington state, USA)

et al. 2019

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Abstract. The Olympic Mountains of Washington state (USA) represent the aerially exposed accretionary wedge of the Cascadia Subduction Zone and are thought to be in flux steady state, whereby the mass outflux (denudation) and influx (tectonic accretion) into the mountain range are balanced. We use a multi-method approach to investigate how temporal variations in the influx and outflux could affect previous interpretations of flux steady state. This includes the analysis of published and new thermochronometric ages for (U–Th) ∕ He dating of apatite and zircon (AHe and ZHe, respectively), fission-track dating of apatite and zircon (AFT and ZFT, respectively), 1-D thermo-kinematic modeling of thermochronometric data, and independent estimates of outflux and influx. In total, we present 61 new AHe, ZHe, AFT, and ZFT thermochronometric ages from 21 new samples. AHe ages are generally young (< 4 Ma), and, in some samples, AFT ages (5–8 Ma) overlap ZHe ages (7–9 Ma) within uncertainties. Thermo-kinematic modeling shows that exhumation rates are temporally variable, with rates decreasing from > 2 to < 0.3 km Myr−1 around 5–7 Ma. With the onset of Plio–Pleistocene glaciation, exhumation rates increased to values > 1 km Myr−1. This demonstrates that the material outflux varies through time, requiring a commensurate variation in influx to maintain flux steady state. Evaluation of the offshore and onshore sediment record shows that the material influx is also variable through time and that the amount of accreted sediment in the wedge is spatially variable. This qualitatively suggests that significant perturbations of steady state occur on shorter timescales (105–106 years), like those created by Plio–Pleistocene glaciation. Our quantitative assessment of influx and outflux indicates that the Olympic Mountains could be in flux steady state on long timescales (107 years).

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Section: Temporal Variations In Exhumationsupporting

confidence: 82%

Section: Geology and Glacial History Of The Olympic Mountainsmentioning

confidence: 99%

Section: Geology and Glacial History Of The Olympic Mountainsmentioning

confidence: 99%

Section: Pattern Of Exhumationmentioning

confidence: 99%

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How steady are steady-state mountain belts? A reexamination of the Olympic Mountains (Washington state, USA)

et al. 2019

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“…[Hemming, 2004], we would predict no CIS response to these events. We note, however, that there is only one local study supporting the presence of an ice sheet during H5 [Easterbrook, 1986], while there are numerous locations in the Puget Lowland area [Booth et al, 2004] and eastern British Columbia that were ice free sometime prior to $50 ka [Clague and James, 2002].…”

Section: Triggers For Cordilleran Ice Sheet Calvingmentioning

confidence: 78%

Vulnerability of the Cordilleran Ice Sheet to iceberg calving during late Quaternary rapid climate change events

Hendy

Cosma

2008

Paleoceanography

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[1] We present the first high-resolution record of iceberg calving on the continental slope of Vancouver Island, British Columbia (MD02-2496, 48°58N, 127°02W, 1243 m water depth), through the last glacial from the Cordilleran Ice Sheet (CIS). These previously unknown ice-rafted debris (IRD) events representing significant retreat of the western margin of the CIS out of marine waters show little correspondence with local climate change. High-resolution radiocarbon dating indicates that the younger IRD events coincide with global radiocarbon age plateaus that allow direct correlation with distal climate records where the same plateaus have been identified. The coincidence of episodic shedding of IRD from the CIS with North Atlantic climate events (i.e., North Atlantic Deep Water shutdown, and Heinrich events) begs the question: What drove CIS destabilization? Forcing appears to be external to CIS dynamics perhaps resulting from either eustatic sea level rise or episodes of atmospheric warming over the North American continent.Citation: Hendy, I. L., and T. Cosma (2008), Vulnerability of the Cordilleran Ice Sheet to iceberg calving during late Quaternary rapid climate change events, Paleoceanography, 23, PA2101,

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The late Cenozoic diatom stratigraphy and paleolimnology of Tule Lake, Siskiyou Co. California

Bradbury

1991

J Paleolimnol

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Stratigraphy and chronology of quaternary deposits of the Puget Lowland and Olympic Mountains of Washington and the Cascade Mountains of Washington and Oregon

Cited by 31 publications

References 93 publications

How steady are steady-state mountain belts? A reexamination of the Olympic Mountains (Washington state, USA)

How steady are steady-state mountain belts? A reexamination of the Olympic Mountains (Washington state, USA)

Vulnerability of the Cordilleran Ice Sheet to iceberg calving during late Quaternary rapid climate change events

The late Cenozoic diatom stratigraphy and paleolimnology of Tule Lake, Siskiyou Co. California

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