Paleozoic rocks on the Alaska Peninsula: A section in &lt;i&gt;The United States Geological Survey in Alaska: Accomplishments during 1978&lt;/i&gt;

Detterman, Robert L.; Case, James E.; Wilson, Frederic H.

doi:10.3133/70180323

Cited by 2 publications

(1 citation statement)

References 26 publications

(31 reference statements)

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“…The formation is several hundred meters thick in the area of Chignik Bay, but varies outside the type area, thinning rapidly to the northeast and southwest (Detterman et al 1996). The rock unit is a cyclic sequence of predominately shallow marine to nearshore marine environments in the lower part and predominately continental environments in the upper part of the section (Detterman 1978;Detterman et al 1996). Based on the presence of specific marine bivalves and ammonites, the age of the Chignik Formation is late Campanian to early Maastrichtian (Detterman et al 1996), approximately 72 million years ago.…”

Section: The Cretaceous Chignik Formation Of Aniamentioning

confidence: 99%

The dinosaur-bearing rocks of Aniakchak National Monument and Preserve: A fossil resource of global interest

Fiorillo,

Hamon

2024

Parks Stewardship Forum

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The first discovery of any dinosaur remains in a US National Park Service unit in Alaska occurred in 2001 in Aniakchak National Monument and Preserve. The record consisted of the track of a pes impression, or track made by the foot of a hadrosaur (duck-billed dinosaur) and an associated manus impression, or track made by a hand. Subsequent work has shown the original track discovery was not unique, and that the coastal exposures of the Cretaceous Chignik Formation in Aniakchak National Monument and Preserve contain a remarkable number of tracks. Further, because of the limited faulting, the several hundred meters of section found along this coastal set of exposures provide a remarkably complete look at an ancient high-latitude dinosaurian ecosystem and are of outstanding universal value.

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Section: The Cretaceous Chignik Formation Of Aniamentioning

confidence: 99%

The dinosaur-bearing rocks of Aniakchak National Monument and Preserve: A fossil resource of global interest

Fiorillo,

Hamon

2024

Parks Stewardship Forum

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Geophysical investigation of a Suture Zone: The Border Ranges Fault of southern Alaska

Fisher¹,

Huene²

1984

J. Geophys. Res.

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The Border Ranges fault separates structurally complex accreted Cretaceous rocks from less deformed middle or late Paleozoic and younger rocks in the Cook‐Shelikof basin. Of the five types of geophysical data used to investigate this fault, gravity data give the clearest indication of its presence and crustal structure. For at least 400 km along the fault, gravity anomalies include a +20 to +30 mGal peak along the fault's upper plate and a −40 mGal trough along the lower plate. The paired anomaly can be modeled satisfactorily by a simple step, in a deep dense layer, that lies within 3 km of the projected offshore location of the fault. Relatively low‐density rocks lie along the fault's lower plate to a depth of about 10 km, and the upper part of the fault dips within 20° of vertical. Satellite altimetry data show that two circular geoid lows lie along the Border Ranges fault and coincide with lows in free air gravity data. Seismic refraction and seismic reflection data suggest that the large‐scale density anomalies that cause both types of lows must lie at depths greater than about 1 km within the margin. Three regional magnetic anomalies (Knik Arm, Seldovia, and Shelikof) terminate at the Border Ranges fault, suggesting that the fault truncates obliquely rocks that lie along its northwest side. Six seismic reflection lines cross the Border Ranges fault, but none of them shows reflections from it. The absence of such reflections probably results from the fault's steep dip and from the presence of strong water bottom multiples in the data. From the Late Jurassic until the early Late Cretaceous, the magmatic arc near the Cook‐Shelikof basin was inactive, and we infer that the predominant motion along the Border Ranges fault was strike slip. Resurgent Late Cretaceous magmatism was contemporaneous with uplift of rocks along the northwest side of the Border Ranges fault and with deformation of turbidite sequences in the fault's lower plate. We propose that during the Late Cretaceous, motion along the Border Ranges changed from strike slip to reverse. Cenozoic rocks near the fault show no evidence for post‐Cretaceous fault movement.

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Paleozoic rocks on the Alaska Peninsula: A section in <i>The United States Geological Survey in Alaska: Accomplishments during 1978</i>

Cited by 2 publications

References 26 publications

The dinosaur-bearing rocks of Aniakchak National Monument and Preserve: A fossil resource of global interest

The dinosaur-bearing rocks of Aniakchak National Monument and Preserve: A fossil resource of global interest

Geophysical investigation of a Suture Zone: The Border Ranges Fault of southern Alaska

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