scholarly journals Structure and seismotectonics of the Mendocino Triple Junction, California

2003 ◽  
Vol 108 (B5) ◽  
Author(s):  
Timothy J. Henstock ◽  
Alan Levander
Keyword(s):  
Triple Junction ◽  
Mendocino Triple Junction

HOLOCENE MARINE TERRACE FORMATION NEAR THE MENDOCINO TRIPLE JUNCTION: PALEOSEISMIC HISTORY DERIVED FROM HIGH RESOLUTION LIDAR

2019 ◽  
Author(s):  
Brandon Crawford ◽  
◽  
Evan J. Hartshorn ◽  
Mark A. Hemphill-Haley ◽  
Melanie J. Michalak
Keyword(s):  
High Resolution ◽  
Triple Junction ◽  
Marine Terrace ◽  
Mendocino Triple Junction

Boulders as a lithologic control on river and landscape response to tectonic forcing at the Mendocino triple junction

2020 ◽  
Author(s):  
Charles M. Shobe ◽  
Georgina L. Bennett ◽  
Gregory E. Tucker ◽  
Kevin Roback ◽  
Scott R. Miller ◽  
...  
Keyword(s):  
Triple Junction ◽  
High Elevation ◽  
River Channels ◽  
Erosion Rates ◽  
Coastal Belt ◽  
Sediment Mass ◽  
Mendocino Triple Junction ◽  
Landscape Response ◽  
Channel Steepness ◽  
Tectonic Forcing

Constraining Earth’s sediment mass balance over geologic time requires a quantitative understanding of how landscapes respond to transient tectonic perturbations. However, the mechanisms by which bedrock lithology governs landscape response remain poorly understood. Rock type influences the size of sediment delivered to river channels, which controls how efficiently rivers respond to tectonic forcing. The Mendocino triple junction region of northern California, USA, is one landscape in which large boulders, delivered by hillslope failures to channels, may alter the pace of landscape response to a pulse of rock uplift. Boulders frequently delivered by earthflows in one lithology, the Franciscan mélange, have been hypothesized to steepen channels and slow river response to rock uplift, helping to preserve high-elevation, low-relief topography. Channels in other units (the Coastal Belt and the Franciscan schist) may experience little or no erosion inhibition due to boulder delivery. Here we investigate spatial patterns in channel steepness, an indicator of erosion resistance, and how it varies between mélange and non-mélange channels. We then ask whether lithologically controlled boulder delivery to rivers is a possible cause of steepness variations. We find that mélange channels are steeper than Coastal Belt channels but not steeper than schist channels. Though channels in all units steepen with increasing proximity to mapped hillslope failures, absolute steepness values near failures are much higher (∼2×) in the mélange and schist than in Coastal Belt units. This could reflect reduced rock erodibility or increased erosion rates in the mélange and schist, or disproportionate steepening due to enhanced boulder delivery by hillslope failures in those units. To investigate the possible influence of lithology-dependent boulder delivery, we map boulders at failure toes in the three units. We find that boulder size, frequency, and concentration are greatest in mélange channels and that Coastal Belt channels have the lowest concentrations. Using our field data to parameterize a mathematical model for channel slope response to boulder delivery, we find that the modeled influence of boulders in the mélange could be strong enough to account for some observed differences in channel steepness between lithologies. At the landscape scale, we lack the data to fully disentangle boulder-induced steepening from that due to spatially varying erosion rates and in situ rock erodibility. However, our boulder mapping and modeling results suggest that lithology-dependent boulder delivery to channels could retard landscape adjustment to tectonic forcing in the mélange and potentially also in the schist. Boulder delivery may modulate landscape response to tectonics and help preserve high-elevation, low-relief topography at the Mendocino triple junction and elsewhere.

scholarly journals Differences in channel and hillslope geometry record a migrating uplift wave at the Mendocino triple junction, California, USA

Geology ◽  
2019 ◽  
Vol 48 (2) ◽  
pp. 184-188 ◽  
Author(s):  
Fiona J. Clubb ◽  
Simon M. Mudd ◽  
Martin D. Hurst ◽  
Stuart W.D. Grieve
Keyword(s):  
Triple Junction ◽  
Land Surface ◽  
Plate Motion ◽  
Topographic Analysis ◽  
Channel Response ◽  
Mendocino Triple Junction ◽  
Uplift Rates ◽  
Order Of Magnitude ◽  
Landscape Morphology ◽  
Channel Steepness

Abstract Tectonic plate motion, and the resulting change in land surface elevation, has been shown to have a fundamental impact on landscape morphology. Changes to uplift rates can drive a response in fluvial channels, which then drives changes to hillslopes. Because hillslopes respond on different time scales than fluvial channels, investigating the geometry of channels and hillslopes in concert provides novel opportunities to examine how uplift rates may have changed through time. Here we perform coupled topographic analysis of channel and hillslope geometry across a series of catchments at the Mendocino triple junction (MTJ) in northern California, USA. These catchments are characterized by an order-of-magnitude difference in uplift rate from north to south. We find that dimensionless hillslope relief closely matches the uplift signal across the area and is positively correlated with channel steepness. Furthermore, the range of uncertainty in hillslope relief is lower than that of channel steepness, suggesting that it may be a more reliable recorder of uplift in the MTJ region. We find that hilltop curvature lags behind relief in its response to uplift, which in turn lags behind channel response. These combined metrics show the northward migration of the MTJ and the corresponding uplift field from topographic data alone.

Morphology and growth history of delgada fan: Implications for the Neogene evolution of Point Arena Basin and the Mendocino Triple Junction

1989 ◽  
Vol 94 (B3) ◽  
pp. 3139-3158 ◽  
Author(s):  
David E. Drake ◽  
David A. Cacchione ◽  
James V. Gardner ◽  
David S. McCulloch ◽  
Douglas Masson
Keyword(s):  
Triple Junction ◽  
Growth History ◽  
Mendocino Triple Junction ◽  
History Of

Transition from slab to slabless: Results from the 1993 Mendocino triple junction seismic experiment

Geology ◽  
1996 ◽  
Vol 24 (3) ◽  
pp. 195 ◽  
Author(s):  
Bruce C. Beaudoin ◽  
Nicola J. Godfrey ◽  
Simon L. Klemperer ◽  
Christof Lendl ◽  
Anne M. Trehu ◽  
...  
Keyword(s):  
Triple Junction ◽  
Seismic Experiment ◽  
Mendocino Triple Junction

Internal deformation of the southern Gorda plate: Fragmentation of a weak plate near the Mendocino triple junction

Geology ◽  
2001 ◽  
Vol 29 (8) ◽  
pp. 691 ◽  
Author(s):  
Sean P.S. Gulick ◽  
Anne S. Meltzer ◽  
Timothy J. Henstock ◽  
Alan Levander
Keyword(s):  
Triple Junction ◽  
Mendocino Triple Junction ◽  
Internal Deformation ◽  
Gorda Plate
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