Plate motions recorded in tectonostratigraphic terranes of the Franciscan complex and evolution of the Mendocino triple junction, northwestern California

McLaughlin, Robert J.; Sliter, William V.; Frederiksen, Norman; Harbert, William; McCulloch, David S.

doi:10.3133/b1997

Cited by 12 publications

(2 citation statements)

References 23 publications

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“…The greater diversity of dominant grain sizes observed in channels underlain by harder rocks (Figure 7) is also consistent with observations that low sediment supply channels may adjust primarily through changes in sediment composition without substantial adjustments to downstream geometry (Dietrich et al, 1989;Madej et al, 2009;Eaton and Church, 2009;Pfeiffer et al, 2017). Furthermore, field sites in highly erosive sedimentary settings typical of the northern California coastal range -such as fractured mudstone and sandstone (McLaughlin et al, 1994)-exhibited the widest channels (large gravel-cobble pool-riffle), supporting the idea that streams draining erosive lithology can be wider as a result of long-term high sediment inputs (Roering et al, 2005;May et al, 2013;Beeson et al, 2018). It should be noted, however, that these statistical outcomes do not account for potential correlation among geospatial variables.…”

Section: Channel Morphology Can Be Distinguished Based On Landscape Propertiessupporting

confidence: 85%

Channel‐reach morphology and landscape properties are linked across a large heterogeneous region

Lane

Guillon

Byrne

et al. 2021

Earth Surf Processes Landf

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Given the complex array of processes influencing river networks, conceptual frameworks of rivers are critical to our understanding of channel processes and response potential as well as restoration efforts. Yet despite their wide usage, many classifications are based on limited observations over homogenous landscapes, raising questions about their general applicability and quantitative thresholds. Leveraging a large, transect-based morphological field dataset across California, USA, we use data-driven methods to evaluate multivariate patterns in channel morphology and linkages with landscape properties considering a diversity of physioclimatic settings. Emergent patterns highlight the variability in channel form observed across an extensive dataset over heterogeneous but spatially linked watersheds. In general, identified dominant channel attributes and landscape properties align with established channel types defined through expert judgement, but key differences also emerge. Similar to past studies, bed sediment composition and sub-reach depth variability were discriminating channel attributes. The dominance of landscape properties associated with sediment supply or transport capacity suggests that morphological diversity largely reflects these differences as posited by prior classifications. Results also show some channel forms to be largely independent of valley confinement, with several channel bedforms and dominant grain sizes occurring across valley settings. This data analysis study demonstrates the utility of considering channel reaches and landscapes as multidimensional features to elucidate and test established geomorphic understanding over large field datasets.

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Section: Channel Morphology Can Be Distinguished Based On Landscape Propertiessupporting

confidence: 85%

Channel‐reach morphology and landscape properties are linked across a large heterogeneous region

Lane

Guillon

Byrne

et al. 2021

Earth Surf Processes Landf

View full text Add to dashboard Cite

show abstract

“…5, 6), and again, the backstop configuration here is quite different than in region 3 to the north. The inboard static backstop forms the eastwarddipping fault boundary between the Klamath terrane on the east and various terranes of the Franciscan Com plex to the west (Blake et al, 1985;McLaughlin et al, 1994;McCrory, 2000). Farther west within the Franciscan Complex, there is a distinct materi alstrength boundary between the older (Cretaceous and Jurassic) Central belt rocks and the younger (Paleogene and Cretaceous) Coastal belt rocks that we classify as another static backstop located 50 to 75 km from the deformation front.…”

Section: Region 4-southern Oregon and Northern California (405°-435°n)mentioning

confidence: 89%

Systematic characterization of morphotectonic variability along the Cascadia convergent margin: Implications for shallow megathrust behavior and tsunami hazards

Watt

Brothers

2020

Geosphere

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Studies of recent destructive megathrust earthquakes and tsunamis along subduction margins in Japan, Sumatra, and Chile have linked forearc morphology and structure to megathrust behavior. This connection is based on the idea that spatial variations in the frictional behavior of the megathrust influence the tectono-morphological evolution of the upper plate. Here we present a comprehensive examination of the tectonic geomorphology, outer wedge taper, and structural vergence along the marine forearc of the Cascadia subduction zone (offshore northwestern North America). The goal is to better understand geologic controls on outer wedge strength and segmentation at spatial scales equivalent to rupture lengths of large earthquakes (≥M 6.7), and to examine potential linkages with shallow megathrust behavior. We use cross-margin profiles, spaced 25 km apart, to characterize along-strike variation in outer wedge width, steepness, and structural vergence (measured between the toe and the outer arc high). The width of the outer wedge varies between 17 and 93 km, and the steepness ranges from 0.9° to 6.5°. Hierarchical cluster analysis of outer wedge width and steepness reveals four distinct regions that also display unique patterns of structural vergence and shape of the wedge: Vancouver Island, British Columbia, Canada (average width, linear wedge, seaward and mixed vergence); Washington, USA (higher width, concave wedge, landward and mixed vergence); northern and central Oregon, USA (average width, linear and convex wedge, mixed and seaward vergence); and southern Oregon and northern California, USA (lower width, convex wedge, seaward and mixed vergence). Variability in outer wedge morphology and structure is broadly associated with along-strike megathrust segmentation inferred from differences in oceanic asthenospheric velocities, patterns of episodic tremor and slow slip, GPS models of plate locking, and the distribution of seismicity near the plate interface. In more detail, our results appear to delineate the extent, geometry, and lithology of dynamic and static backstops along the margin. Varying backstop configurations along the Cascadia margin are interpreted to represent material-strength contrasts within the wedge that appear to regulate the along- and across-strike taper and structural vergence in the outer wedge. We argue that the morphotectonic variability in the outer wedge may reflect spatial variations in shallow megathrust behavior occurring over roughly the last few million years. Comparing outer wedge taper along the Cascadia margin to a global compilation suggests that observations in the global catalog are not accurately representing the range of heterogeneity within individual margins and highlights the need for detailed margin-wide morphotectonic analyses of subduction zones worldwide.

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Effects of triple junction migration and glacioeustatic cyclicity on evolution of upper slope morphologies, offshore Eel River Basin, northern California

2003

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Plate motions recorded in tectonostratigraphic terranes of the Franciscan complex and evolution of the Mendocino triple junction, northwestern California

Cited by 12 publications

References 23 publications

Channel‐reach morphology and landscape properties are linked across a large heterogeneous region

Channel‐reach morphology and landscape properties are linked across a large heterogeneous region

Systematic characterization of morphotectonic variability along the Cascadia convergent margin: Implications for shallow megathrust behavior and tsunami hazards

Effects of triple junction migration and glacioeustatic cyclicity on evolution of upper slope morphologies, offshore Eel River Basin, northern California

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