Potassic mafic magmatism in the Kigluaik gneiss dome, northern Alaska: A geochemical study of arc magmatism in an extensional tectonic setting

Amato, Jeffrey M.; Wright, James E.

doi:10.1029/96jb03224

Cited by 24 publications

(22 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…High La/Ta ratios typically indicate the involvement of continental crust, either as a component added by assimilation during crystallization in magma chambers or magma transport, or as a contaminant added directly in the mantle source (e.g., sediment subduction into the mantle). High La/Ta ratios are typical of the middle to Late Cretaceous magmatic rocks in the Seward Peninsula region that have been interpreted to be subduction related (Moll-Stalcup and Arth, 1989;Miller, 1989;Moll-Stalcup, 1994;Amato and Wright, 1997). The combined geochemical and geochronologic evidence argues favorably for the interpretation that these xenoliths are maµc cumulates that formed during middle to Late Cretaceous subduction-related magmatism, and were variably deformed and recrystallized during Late Cretaceous or early Tertiary extension.…”

Section: Crustal Xenolithsmentioning

confidence: 86%

“…If the xenoliths are of crustal origin (cumulates), then the deformed character of many pyroxene and olivine grains implies that they must have formed prior to the Late Cretaceous, the last major deformation event in the region. However, this seems unlikely because the trace element compositions of these xenoliths (Table 2) lack the signatures of suprasubduction-zone magmatism (e.g., high La/Nb) that are characteristic of the Cretaceous magmatism in the Bering Sea region (Moll-Stalcup and Arth, 1989;Miller, 1989;Moll-Stalcup, 1994;Amato and Wright, 1997). The trace element compositions of the pyroxenite xenoliths, especially those of the amphibole pyroxenites (Figs.…”

Section: Amphibolite-pyroxenite Xenolithsmentioning

confidence: 97%

“…The composition of this granite plots along the compositional trends of maµc to felsic plutonic rocks from the Kigluaik gneiss dome on the Seward Peninsula (Amato and Wright, 1997). The REE and trace element patterns (Figs.…”

Section: Crustal Xenolithsmentioning

confidence: 98%

“…As noted here, there have been several episodes of crustal extension in western Alaska since the Late Cretaceous. Magmatism associated with the main phase of extension in the Late Cretaceous is truly bimodal (Amato et al, 1994;Amato and Wright, 1997). Maµc and felsic plutonic (e.g., Seward Peninsula and YukonKoyukuk basin) and volcanic rocks (Saint Lawrence Island and Chukotka Peninsula) are exposed throughout the Cretaceous magmatic belt (southeast Alaska to northeast China).…”

Section: Relationship Between Extension and Volcanism In Alaskamentioning

confidence: 99%

“…1), and are characterized by small-volume eruptions of tholeiitic to alkaline magmas with intraplate afµnity (e.g., Hoare and Con- Moll-Stalcup (1994), Kirschner (1994), Plafker and Berg (1994), and Amato and Wright (1997).…”

Section: Introductionmentioning

confidence: 98%

See 4 more Smart Citations

Evolution of crust and mantle beneath the Bering Sea region: Evidence from xenoliths and late Cenozoic basalts

Wirth¹,

Grandy²,

Kelley³

et al. 2002

Tectonic Evolution of the Bering Shelf-Chukchi Sea-Artic Margin and Adjacent Landmasses

View full text Add to dashboard Cite

Late Cenozoic volcanic centers throughout the Bering Sea region of Alaska consist of small-volume eruptions of ×ows and cones of tholeiitic to alkaline basalt. Peridotite (spinel lherzolite, websterite, wehrlite, and pyroxenite) and gabbro xenoliths are abundant in some of the most alkaline ×ows and cones. Spinel lherzolite xenoliths are characterized by granuloblastic-equant and coarse-equant textures typical of mantle peridotites and yield equilibration temperatures of 1000-1200 °C (1.5 GPa). Relative to other spinel lherzolites worldwide, these xenoliths have low MgO and high Fe 2 O 3 T and are similar to some modeled compositions for fertile mantle. However, these xenoliths are relatively enriched in the light rare earth elements (REE), Th, U, K, Nb, and Ta. Rare amphibole peridotite xenoliths have textures and compositions that are consistent with an origin as pyroxenite veins in the mantle that were variably deformed and metasomatized with potassium-rich ×uids. These xenoliths have concave-up light REE patterns similar to those of the host basalts, suggesting that the alkaline melts may have been produced by melting of amphibole-bearing mantle peridotites. Gabbroic xenoliths are variably deformed and recrystallized at relatively high pressure (0.4-0.6 GPa). Trace element ratios (e.g., Ba/Nb, La/Nb) indicate that these xenoliths crystallized from melts that were produced in a suprasubduction-zone setting and suggest that they represent cumulates that formed in the lower crust during Late Cretaceous subduction. We suggest that these cumulates are the source of the strong re×ec-tions that are observed in seismic re×ection proµle images of the Bering Sea region.Volcanic ×ows consist of tholeiite, olivine tholeiite, alkali-olivine basalt, and basanite, whereas cones consist mostly of alkali-olivine basalt and basanite. Geochemical variations within each volcanic µeld largely re×ect the effects of fractionation and melting (depth and fraction of melting), whereas between-µeld geochemical differences are largely due to source composition differences. The enriched incompatible trace element compositions (light REE, Ba, Th, Nb, Ta) and ratios (Th/Ta, Rb/Zr, Nb/La, La/Yb) are similar to intraplate basalts from ocean island and continental extensional settings. In particular, the compositions of Bering Sea basalts are similar to those of the diffuse volcanic province of Southeast Asia, a region where late Cenozoic volcanism has been related to tectonic extrusion along reactivated strike-slip faults.

show abstract

Section: Crustal Xenolithsmentioning

confidence: 86%