Author: Rick D. SchroederPublisher:
ISBN:
Category :
Languages : en
Pages : 382
Book Description
Kinematic Evolution of the Maacama Fault Line, Northern California Coast Ranges
Author: Rick D. SchroederMaacama Fault Study, Sonoma/Mendocino Counties
Author: Maacama Fault Study
Author: United States. Army. Corps of Engineers. San Francisco DistrictPublisher:
ISBN:
Category : Faults (Geology)
Languages : en
Pages : 356
Book Description
Tectonics of the Northern California Coast Ranges, Past and Present, as Inferred from the Analysis of Kinematic Data
Author: Larry D. GuentherEvolution of an Intermontane Basin Along the Maacama Fault, Little Lake Valley, Northern California
Author: Gwendolyn EricksonPublisher:
ISBN:
Category : Basins (Geology)
Languages : en
Pages : 218
Book Description
Associated with the northern strands of the San Andreas fault system in California is a series of small intermontane basins. While it is tempting to ascribe their formation to simple 'pull-apart' tectonics along the dominantly strike-slip fault strands, direct evidence for basin genesis is lacking. In this study, a detailed gravity survey throughout the Little Lake Valley region (Willits, California) provides constraints on mechanisms of basin formation along this young segment of the San Andreas fault system. Interpretation of isostatic gravity anomaly data provides insight into fault geometry, basin structure, and thickness of Quaternary fill in Little Lake Valley, California. Although the active strike-slip Maacama fault zone diagonally trends through the southwest part of the valley, gravity and geologic interpretations indicate the valley conceals an earlier basin and faulting history. Gravity models, mapped geology, and double-difference relocated seismicity data indicate that Little Lake Valley basin geometry records a tectonic history which includes subduction, extension, and presently, dextral strike-slip motion along the Maacama fault. The isostatic gravity anomaly of Little Lake Valley basin is negative (up to 13 mGals) and rhombic in shape. Modeling indicates two splays, less than a km apart, of a reverse up-to-the-east East Valley fault. Cumulative vertical fault displacement along the East Valley fault increases in the southern portion of the valley. Gravity modeling and geology indicate two normal, up-to-the-northwest faults; one in the northwest portion of Little Lake Valley and the other to the south in Redwood Valley. Normal faults are presumed to be temporally related to Clear Lake volcanics (2 Ma to 10ka), located 45 km southwest of Little Lake Valley, and migration of the Mendocino triple junction to the north. While focal mechanisms of double-difference relocated seismicity indicate reverse and normal faults no longer accommodate significant vertical motion, portions of these structures are accommodating strike-slip motion. Consequently, the Maacama fault is occupying an upward-branching flower structure which takes advantage of pre-existing fault structures and may sole into a regional detachment at approximately 10 km depth. Although Little Lake Valley was not initiated as a strike-slip basin, development of the Maacama fault may evolve Little Lake Valley into a strike-slip basin.
Kinematics of Transrotational Tectonism in the California Transverse Ranges and Its Contribution to Cumulative Slip Along the San Andreas Transform Fault System
Author: William R. DickinsonPublisher: Geological Society of America
ISBN: 0813723051
Category : Science
Languages : en
Pages : 53
Book Description
Late Neogene and Quaternary Landscape Evolution of the Northern California Coast Ranges
Author: Jane LockPublisher:
ISBN:
Category : Geology, Stratigraphic
Languages : en
Pages : 15
Book Description
A landscape records the surface response to tectonics at time scales intermediate between short time-scale information derived from seismic imaging and global positioning systems and the long-term geologic record. We link late Neogene and Quaternary deposits and landforms in the northern California Coast Ranges to the tectonics of the Mendocino triple junction. In the northern California Coast Ranges, the Mendocino crustal conveyor geodynamic model describes crustal thickening, thinning, and dynamic topography that produce a “double-humped” pattern of uplift that migrates northward with the Mendocino triple junction. The tectonics are manifest in the drainage system and elevation pattern of the Coast Ranges. At long wavelengths, the elevation pattern closely matches the predicted double-peaked shape of Mendocino crustal conveyor topography, and the high points of uplift control the location of drainage divides. Presently, the divide between the Russian and Eel Rivers and the divide between the Eel and Van Duzen Rivers approximately correspond to the peaks of uplift predicted by the Mendocino crustal conveyor model. As the triple junction migrates northward, the double-humped pattern of uplift and subsidence migrates, and the Coast Ranges emerge. Smaller drainages develop and evolve by stream capture and flow reversal, and the two main divides migrate in concert with the triple junction. In contrast to the systematic development of the small streams, the largest trunk streams can maintain grade through regions of high uplift, and coastal river mouths remain stationary despite the uplift moving north. Before ca. 2 Ma, the majority of the Coast Range drainage flowed to a southern coastal outlet near the present mouth of the Russian River. At 2 Ma, facilitated by headwater stream capture at key locations, the drainage direction reversed, and the majority of Coast Range rivers now drain into the north-flowing Eel River. The major drainage reorganization at 2 Ma highlights the potential for complexity in geomorphic response to tectonics.
The San Andreas Fault System, California
Author: Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 316
Book Description
An overview of the history, geology, geomorphology, geophysics, and seismology of the most well known plate tectonic boundary in the world.
Geology of the South Yolla Bolly Area, Northern California, and Its Tectonic Implications
Author: Dan Michael WorrallPublisher:
ISBN:
Category : Geology
Languages : en
Pages : 612
Book Description
Regional Geology of Mount Diablo, California
Author: Raymond SullivanPublisher:
ISBN: 9780813782171
Category : Diablo, Mount (Calif.)
Languages : en
Pages :
Book Description