Surficial geologic map along the Castle Mountain Fault between Houston and Hatcher Pass Road, Alaska

Haeussler, Peter J.

doi:10.3133/ofr98480

Cited by 8 publications

(5 citation statements)

References 6 publications

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“…Modern glacially influenced fluvial systems (e.g., Susitna, Kahiltna, and Yentna rivers) flow southward from the Alaska Range and merge into a major trunk system (Susitna River) that drains into the upper Cook Inlet estuary. Considered a northern extension of Cook Inlet basin, the Susitna basin is bisected by the Castle Mountain fault (Haeussler, 1998;Haeussler et al, 2002). Exploratory drillholes and gravity surveys penetrate Ͼ4 km of Paleocene-Miocene conglomerate, carbonaceous sandstone, mudstone, and coal deposited in fluvial-lacustrine environments (e.g., Hackett, 1977;Merritt, 1986;Meyer et al, 1996;Meyer and Boggess, 2003b).…”

Section: Susitna Basinmentioning

confidence: 99%

Mesozoic and Cenozoic tectonic growth of southern Alaska: A sedimentary basin perspective

Trop¹,

Ridgway²

2007

Special Paper 431: Tectonic Growth of a Collisional Continental Margin: Crustal Evolution of Southern Alaska

122

175

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Mesozoic and Cenozoic sedimentary strata exposed throughout southern Alaska contain a rich archive of information on the growth of collisional continental margins through the processes of terrane accretion, magmatism, accretionary prism development, and subduction of oceanic spreading ridges. Two major collisional events define the tectonic growth of southern Alaska: Mesozoic collision of the Wrangellia composite terrane and Cenozoic collision of the Yakutat terrane. The sedimentary record of these two collisional events can be summarized as follows. (1) Middle Jurassic volcaniclastic and sedimentary strata represent shallow-marine deposition in narrow subbasins adjacent to the volcanic edifice of the south-facing, intraoceanic Talkeetna arc. (2) Late Jurassic syndepositional regional shortening resulted in thick sections of conglomerate in proximal parts of both retroarc and forearc basins. In distal retroarc depocenters, fine-grained turbidite sedimentation commenced in a series of basins that presently extend for Ͼ2000 km along strike. This time interval also marked cessation of magmatism and rapid exhumation of the Talkeetna oceanic arc. We interpret these observations to reflect initial oblique collision, younging to the northwest, of the Wrangellia composite terrane with the continental margin of western North America. (3) During Early Cretaceous time, Jurassic retroarc basin strata were incorporated into an expanding north-verging thrust belt, and sediment was bypassed into more distal collisional retroarc basins located within the suture zone. Compositional data from these collisional basins show that the Wrangellia composite terrane was exhumed to deep stratigraphic levels. Detrital zircon ages from strata in these basins record some sediment derivation from source areas with North American continental margin affinity. Our data clearly show that the Wrangellia composite terrane and the former continental margin were in close proximity by this time. Accretion of this oceanic terrane and associated basinal deposits marked one of the largest additions of juvenile crust to western North America. The collision of the Wrangellia composite terrane also resulted in a change in subduction parameters that eventually prompted development of a new south-facing arc system, the Chisana arc. Construction of this arc was contemporaneous with renewed forearc basin subsidence and sedimentation. (4) Late Early Cretaceous to early Late Cretaceous time was characterized by regional deformation of retroarc collisional basin strata by south-verging thrust faults that are part of a regional thrust belt that

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Section: Susitna Basinmentioning

confidence: 99%

Mesozoic and Cenozoic tectonic growth of southern Alaska: A sedimentary basin perspective

Trop¹,

Ridgway²

2007

Special Paper 431: Tectonic Growth of a Collisional Continental Margin: Crustal Evolution of Southern Alaska

122

175

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“…Discontinuous scarps define the fault between Houston and the road to Hatcher Pass, but no faultline scarps have been identified east of the Hatcher Pass Road. The extent of the fault was mapped by others (1974, 1976a), Clardy (1974), andHaeussler (1998). Historical earthquakes in 1984 (Lahr and others, 1986) and 1996 had right-lateral offset along the part of the fault without a scarp.…”

Section: Castle Mountain Faultmentioning

confidence: 95%

“…1, 3) is recognized in bedrock in the Talkeetna Mountains (Detterman and others, 1976a;Fuchs, 1980). The western part of the fault has a Holocene fault scarp (Detterman and others, 1974;Haeussler, 1998;Willis and others, 2007). The fault has a history extending back at least 47 million years (Parry and others, 2001).…”

Section: Castle Mountain Faultmentioning

confidence: 99%

Location and extent of Tertiary structures in Cook Inlet Basin, Alaska, and mantle dynamics that focus deformation and subsidence

Haeussler¹,

Saltus²

2011

Professional Paper

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“…Aspects of the fault's character are enigmatic. The fault's linear trace (Haeussler, 1998), historical seismicity (Lahr et al, 1986), Riedel shears imaged on LiDAR (Koehler et al, 2014), and long-term geologic history (Trop, 2008) all indicate right-lateral strike slip motion on the Castle Mountain Fault. However, contractional deformation across the fault is indicated by the consistent north-side-up fault scarp, offsets in some paleoseismic trenches, a 4-km-wide anticline adjacent to, and north of, the fault trace identified on seismic reflection profiles.…”

Section: 6mentioning

confidence: 99%

Updating the Crustal Fault Model for the 2023 National Seismic Hazard Model for Alaska

Haeussler,

Bender,

Powers

et al. 2023

Preprint

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We present the crustal fault model for Alaska, based on geologic observations, as a primary input for the 2023 revision of the U.S. Geological Survey National Seismic Hazard Model (NSHM). We update the 2013 Alaska Quaternary fault and fold database (Koehler, 2013) with subsequent findings to produce a simplified model of 105 fault sections and four fault zone polygons with basic geologic parameters including slip sense and rate. Significant updates from prior maps include: 1) A slip rate of ~53 mm/yr on the Queen Charlotte Fault system indicating it accommodates all of the plate boundary motion. 2) Quantified long-term slip rates on megathrust splay faults in the southern Prince William Sound region and near Kodiak Island. 3) Improved details of structures in the Chugach-St. Elias orogen. 4) Revised characterization of Castle Mountain Fault from right-lateral slip to a predominantly reverse fault. 5) Improved Interior Alaska tectonic models that clarify relationships between the Denali Fault, Totschunda Fault, and thrust faults on both sides of the Alaska Range. 6) Identified large earthquake sources in the eastern Brooks Range. 7) Omission of the Chatham Strait section of the Denali Fault. We also describe the growing body of Alaskan lacustrine paleoseismic records of strong shaking, which may offer a test of ground motion recurrence predicted by the 2023 NSHM for crustal, megathrust, and intraslab events. The fault model underscores that the collision of the Yakutat microplate is the dominant driver of active crustal faulting in most of Alaska.

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Surficial geologic map along the Castle Mountain Fault between Houston and Hatcher Pass Road, Alaska

Cited by 8 publications

References 6 publications

Mesozoic and Cenozoic tectonic growth of southern Alaska: A sedimentary basin perspective

Mesozoic and Cenozoic tectonic growth of southern Alaska: A sedimentary basin perspective

Location and extent of Tertiary structures in Cook Inlet Basin, Alaska, and mantle dynamics that focus deformation and subsidence

Updating the Crustal Fault Model for the 2023 National Seismic Hazard Model for Alaska

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