Search engine for discovering works of Art, research articles, and books related to Art and Culture
Javascript must be enabled to continue!
Tectonic and petrologic evolution of the Kodiak batholith and the trenchward belt, Kodiak Island, AK: Contact fault juxtaposition?
View through CrossRef
Two fore‐arc magmatic belts exist in Kodiak Island, the granitic Kodiak batholith and the basaltic trenchward belt. Both are part of the 2100 km long Sanak‐Baranof belt, interpreted to result from trench‐ridge‐trench (T‐R‐T) triple‐junction migration. In this hypothesis, trenchward belt basaltic rocks formed as the spreading ridge first entered the accretionary prism, and the larger Kodiak batholith resulted from a slab window at depth. However, radiometric dates between the two belts differ in age by up to 1–3 Ma. Kodiak batholith U/Pb zircon ages range from 59.2 to 58.4 ± 0.2 Ma (SW‐NE), whereas trenchward belt ages range from 62.6 ± 0.6 (K‐Ar) to 60.15 ± 0.86 (Ar/Ar whole rock) SW‐NE. This suggests that both fore‐arc magmatic belts did not form from a single triple‐junction passage, because at 60–62 Ma the triple junction was several hundred kilometers west of Kodiak Island. Multiple explanations exist for the age disparity between the two belts, including oblique ridge subduction, Contact fault tectonic juxtaposition, slab window thermal lag, multiple triple‐junction passages, or off‐axis ridge magmatism. Geochemical data such as rare earth metal (REE) curves and Zr/Nb of >30 indicate the trenchward belt rocks have a mid‐ocean ridge basalt (MORB)–like character. Major and trace element modeling indicate that trenchward belt rocks resulted from assimilation‐fractional‐crystallization of MORB with Ghost Rocks Formation argillite, whereas the Kodiak batholith formed via partial melting and en masse mobilization of Kodiak Formation metasedimentary rocks with a small basaltic component and subsequent equilibrium‐crystallization and restite separation. The petrologic origin of both belts is compatible with spreading ridge subduction. Fault zone structural data suggest the Kodiak batholith/trenchward belt age differential resulted from oblique ridge subduction and Contact fault displacement.
Title: Tectonic and petrologic evolution of the Kodiak batholith and the trenchward belt, Kodiak Island, AK: Contact fault juxtaposition?
Description:
Two fore‐arc magmatic belts exist in Kodiak Island, the granitic Kodiak batholith and the basaltic trenchward belt.
Both are part of the 2100 km long Sanak‐Baranof belt, interpreted to result from trench‐ridge‐trench (T‐R‐T) triple‐junction migration.
In this hypothesis, trenchward belt basaltic rocks formed as the spreading ridge first entered the accretionary prism, and the larger Kodiak batholith resulted from a slab window at depth.
However, radiometric dates between the two belts differ in age by up to 1–3 Ma.
Kodiak batholith U/Pb zircon ages range from 59.
2 to 58.
4 ± 0.
2 Ma (SW‐NE), whereas trenchward belt ages range from 62.
6 ± 0.
6 (K‐Ar) to 60.
15 ± 0.
86 (Ar/Ar whole rock) SW‐NE.
This suggests that both fore‐arc magmatic belts did not form from a single triple‐junction passage, because at 60–62 Ma the triple junction was several hundred kilometers west of Kodiak Island.
Multiple explanations exist for the age disparity between the two belts, including oblique ridge subduction, Contact fault tectonic juxtaposition, slab window thermal lag, multiple triple‐junction passages, or off‐axis ridge magmatism.
Geochemical data such as rare earth metal (REE) curves and Zr/Nb of >30 indicate the trenchward belt rocks have a mid‐ocean ridge basalt (MORB)–like character.
Major and trace element modeling indicate that trenchward belt rocks resulted from assimilation‐fractional‐crystallization of MORB with Ghost Rocks Formation argillite, whereas the Kodiak batholith formed via partial melting and en masse mobilization of Kodiak Formation metasedimentary rocks with a small basaltic component and subsequent equilibrium‐crystallization and restite separation.
The petrologic origin of both belts is compatible with spreading ridge subduction.
Fault zone structural data suggest the Kodiak batholith/trenchward belt age differential resulted from oblique ridge subduction and Contact fault displacement.
Related Results
Integration Techniques of Fault Detection and Isolation Using Interval Observers
Integration Techniques of Fault Detection and Isolation Using Interval Observers
An interval observer has been illustrated to be a suitable approach to detect and isolate faults affecting complex dynamical industrial systems.
Concerning fault detection, interv...
Aquamarine Mineralization in the Black River Batholith, Yukon Territory, Canada
Aquamarine Mineralization in the Black River Batholith, Yukon Territory, Canada
The central Yukon Territory is renowned for its exceptionally abundant beryl occurrences. In 2003, widespread medium-blue aquamarine mineralization was discovered in the Black Rive...
Geology of Eastern Karakoram, Ladakh District, India
Geology of Eastern Karakoram, Ladakh District, India
The eastern Karakoram lies to the north of the Shyok ophiolite melange belt (commonly known as the Shyok Suture). Metamorphic rocks are limited in occurrence and mainly confined to...
Deformational Processes Accommodating Slip on an Active Low-Angle Normal Fault, Suckling-Dayman Metamorphic Core Complex, Papua New Guinea
Deformational Processes Accommodating Slip on an Active Low-Angle Normal Fault, Suckling-Dayman Metamorphic Core Complex, Papua New Guinea
<p><b>Detachment faults that can be shown to have slipped at dips <30° in highly extended continental crust are referred to as “Low-Angle Normal Faults” (LANFs). The...
Decomposition and Evolution of Intracontinental Strike‐Slip Faults in Eastern Tibetan Plateau
Decomposition and Evolution of Intracontinental Strike‐Slip Faults in Eastern Tibetan Plateau
Abstract:Little attention had been paid to the intracontinental strike‐slip faults of the Tibetan Plateau. Since the discovery of the Longriba fault using re‐measured GPS data in 2...
Quantitative constraints on shortening deformation characteristics of the fold at the south-edge thrust fault of the Yanqi Basin, Southern Tien Shan
Quantitative constraints on shortening deformation characteristics of the fold at the south-edge thrust fault of the Yanqi Basin, Southern Tien Shan
Abstract: The collision and compression between the Indian and Eurasian plates have resulted in intense crustal shortening and deformation in the Tian Shan since the Cenozoic, lead...
Stratigraphy and Tectonics of Ladakh, Eastern Karakoram, Western Tibet and Western Kun Lun
Stratigraphy and Tectonics of Ladakh, Eastern Karakoram, Western Tibet and Western Kun Lun
Abstract
A new geological map on 1:1 million scale has been prepared for the first time, primarily to depict the various stratigraphic and tectonic units of north...
Relative tectonic activity assessment of the northern sumatran fault from geomorphological and morphotectonic analyses
Relative tectonic activity assessment of the northern sumatran fault from geomorphological and morphotectonic analyses
The Northern Sumatran Fault is a part of a trench-parallel strike-slip fault situated in oblique subduction setting. This study aims to assess the relative tectonic activity using ...