Preliminary integrated geologic map databases for the United States: Digital data for the reconnaissance geologic map of the Kodiak Islands, Alaska

Wilson, Frederic H.; Labay, Keith A.; Shew, Nora B.; Mohadjer, Solmaz; Patton, W.W.

doi:10.3133/ofr20051340

Cited by 5 publications

(6 citation statements)

References 3 publications

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“…(c) FeO*/MgO versus SiO2 (wt. %) and age ranges for plutons from: Amatignak Island (red squares), Finger Bay Pluton (orange circles), Hidden Bay plutonic complex (blue diamonds) [ Citron et al , ; Kay and Kay, 1982; Kay et al , , 1990], Attu Island [ Delong and McDowell, 1975; Yogodzinski et al , ; Sheldon, 1986], Ilak Island (brown circles; Fraser and Barnett, 1959; Wilson et al , ), Amchitka's East Cape pluton (black diamond) [ Kay, ; Jicha et al , ] Unalaska's Captain Bay pluton (yellow circles) [ Marlow et al , ; Perfit et al , ], Atka pltuons (gray circle) [ Hein et al , ], and Kagalaska pluton (pink diamond) (Kay and Jicha, unpublished). Calc‐alkaline and tholeiitic fields from Miyashiro [].…”

Section: Resultsmentioning

confidence: 99%

“… Histogram of published geochronologic data >3 Ma for the Aleutian Arc west of 164° W subdivided by existing K‐Ar (pink), 40 Ar/ 39 Ar (light blue), and U‐Pb (green) ages [ Carr et al , ; Cameron and Stone , ; von Huene et al , ; Marlow et al , ; DeLong and McDowell, 1975; Scholl et al , ; DeLong et al , ; Marvin and Cole , ; Hein and McLean, ; Citron et al ,; Borsuk and Tsvetkov, ; McLean et al , ; McLean and Hein, ; Wilson et al , ; Jicha et al , ; Layer et al , ; Cai et al , ] and the 40 Ar/ 39 Ar ages from this study (dark blue, Table 1).…”

Section: Discussionmentioning

confidence: 98%

“…; Kay and Kay , ; Kay et al ., ]. Plutonic rocks from Ilak Island within the Delarof region (Figure and c) have K‐Ar and U‐Pb ages between 14 and 12 Ma [ Wilson et al ., ; Cai et al ., ], consistent with observed arc‐wide Miocene calc‐alkaline plutonism [ Kay et al ., ].…”

Section: Discussionmentioning

confidence: 99%

“…Amatignak Island is the southernmost Delarof Island and is located ∼100 km from the Aleutian trench. It was initially mapped by the USGS as ∼40 km 2 of sedimentary rocks of altered volcanic detritus, well‐bedded tuffaceous siltstone, sandstone, breccia, and deformed argillite [ Fraser and Barnett , ], all of which were assigned to the Eocene Andrew Lake Formation [ Scholl et al ., ; Wilson et al ., ]. Steeply dipping sedimentary rocks comprise much of the southern portion and parts of the northern tip of the island.…”

Section: Geology and Petrology Of The Delarof Islandsmentioning

confidence: 99%

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Eocene to Pleistocene magmatic evolution of the Delarof Islands, Aleutian Arc

Schaen

Jicha

Kay

et al. 2016

Geochem Geophys Geosyst

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The Delarof Islands in the Aleutian Arc near 179º W record ∼37 million years of discontinuous arc magmatism along a SW‐NE cross‐arc transect from near the trench to the active volcanic front. Geochemical and geochronologic data from the pre‐Pleistocene volcanic record in this region are limited and the 40Ar/39Ar, isotopic, and trace element data presented here are the first from units older than the Pleistocene‐Holocene volcanoes (Tanaga, Gareloi). Twenty‐two new 40Ar/39Ar ages establish a temporal framework for geochemical data and reveal that magmatism in the Delarof region was coincident with two arc‐wide magmatic flare ups in the late Eocene/early Oligocene and latest Miocene/Pliocene. Mafic lavas and plutons in the southern Delarofs give 40Ar/39Ar plateau ages ranging from 36.8 ± 0.2 to 26.9 ± 0.6 Ma on Amatignak Island and 37.0 ± 0.2 to 29.3 ± 1.0 Ma on Ulak Island. To the north 25 km, 40Ar/39Ar ages from the central Delarof Islands, Kavalga, Ogliuga, and Skagul are late Miocene (6.28 ± 0.04 Ma) to Pliocene (4.77 ± 0.18 Ma) with younger ages to the northeast. A significant transition in arc chemistry occurs in the Pleistocene where lavas from active volcanoes Gareloi and Tanaga exhibit higher sediment and hydrous fluid signatures (Th/La, Cs/Ta, La/Sm, LILE abundances) and lower 143Nd/144Nd than older Delarof Island units closer to the trench. Similar findings from Eocene‐Miocene lavas from Amchitka to Adak suggest that a previously minor sediment melt component became more pronounced in the Quaternary.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Geology and Petrology Of The Delarof Islandsmentioning

confidence: 99%

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Eocene to Pleistocene magmatic evolution of the Delarof Islands, Aleutian Arc

Schaen

Jicha

Kay

et al. 2016

Geochem Geophys Geosyst

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“… Geological map of the Kodiak archipelago modified after Wilson et al. (2005) with previously published temperature results. Dashed lines in the Kodiak Formation are estimated borders between the Landward, Central, and Seaward Belts.…”

Section: The Anatomy Of the Kodiak Accretionary Complexmentioning

confidence: 99%

Exhuming an Accretionary Prism: A Case Study of the Kodiak Accretionary Complex, Alaska, USA

Rajič,

Raimbourg,

Famin

et al. 2023

Tectonics

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We have carried a structural study across Kodiak accretionary complex in Alaska, USA, in order to describe its thermal structure and decipher the processes of exhumation. The accretionary complex consists of a stack of tectonic mélanges and coherent units. Mélanges are characterized by simple shear deformation with a pervasive network of top‐to‐the‐trench shear zones, whereas coherent units are affected principally by horizontal shortening, except for spatially limited outcrops in Kodiak Central Belt. Peak temperatures estimated using Raman spectroscopy of carbonaceous material range from 220 to 400°C through most of the complex. These temperatures coincide with estimates from metamorphic parageneses and are interpreted as temperatures of deformation achieved under a high gradient due to contemporaneous ridge subduction. The highest temperatures are recorded in the central part of the complex, pointing to a dome‐like structure. Lower temperatures (∼120°C) are recorded along the southeastern border of the complex, in slope sediments unconformably overlying accreted units. Based on the combination of structural and thermal data, we conclude that the rocks constituting the Kodiak complex experienced at least two stages of burial and then exhumation, with vertical motions reaching up to ∼13 km from the Paleocene to the present. Given the pervasive horizontal shortening within the wedge, exhumation resulted from prism thickening contemporaneous with surficial erosion. Recorded subsidence episodes may be local phenomena associated with thrusting or large‐scale processes associated with basal erosion. The rates of vertical motion range from 0.2 to 1.3 mm/yr, comparable with estimates in modern margins.

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