A Detailed Geochemical Study of Island Arc Crust: the Talkeetna Arc Section, South–Central Alaska

Crustal redistribution, crust–mantle recycling and Phanerozoic evolution of the continental crust

“…Instead the oceanic arc is plastered to the edge of the continental mass, effectively as a coherent block with no opportunity for major crustal loss by subduction. A number of the better known examples of oceanic arcs in mountain belts appears to have been accreted in this fashion, most notably the Jurassic Talkeetna Arc in SE Alaska (DeBari and Coleman, 1989;Greene et al, 2006) and the Cretaceous Kohistan Arc (Treloar et al, 1996;Khan et al, 1997;Jagoutz et al, 2007) of the western Himalayas. In both these examples the full crustal section is preserved, suggesting a very efficient accretionary process.…”

Intermediate to felsic middle crust in the accreted Talkeetna arc, the Alaska Peninsula and Kodiak Island, Alaska: An analogue for low‐velocity middle crust in modern arcs

“…Greene et al [2006] used least squares modeling to demonstrate that Talkeetna arc volcanic rocks with up to 57 wt % SiO 2 can be generated from mantle derived basalts by fractional crystallization of cumulate mineral compositions preserved in exposed lower crustal pyroxenites and gabbronorites in the Chugach Mountains. [Kelemen et al, 2003a;Clift et al, 2005a;Greene et al, 2006;Rioux, 2006; this study].…”

“…counts (Table S1) and mineral compositions were measured by electron microprobe [Johnsen, 2007;Hacker et al, 2008;M. E. Rioux, unpublished data, 2004) or estimated based on compositional trends from other Talkeetna plutonic rocks (data from Greene et al [2006] and Hacker et al [2008]). Estimated uncertainties in the plagioclase and biotite compositions lead to small (0.04-0.1 km/s) variations in the predicted seismic velocities.…”

“…The Triassic to Jurassic arc is exposed in four volcanic and plutonic sections in the Chugach Mountains, the Talkeetna Mountains, the Kodiak archipelago and the Alaska Peninsula (Figure 1). Previous research has principally focused on the Chugach Mountains, which preserve a faulted crustal section from residual subarc mantle to subaerial volcanic rocks [DeBari and Coleman, 1989;Kelemen et al, 2003aKelemen et al, , 2003bMehl et al, 2003;Behn and Kelemen, 2006;Greene et al, 2006;Hacker et al, 2008]. The Jurassic batholith on the Alaska Peninsula is distinctly more felsic than the crustal section in the Chugach Mountains and has the potential to provide new insight into the role of silicic magmas in intraoceanic settings.…”

The origin of the Popiel peridotite (Western Sudetes, SW Poland): Metamorphism of the island arc tholeiitic cumulate

“…How ever, the rem nants of pri mary ol iv ine and orthopyroxene grains, as well as the ultra mafic compo si tion, point to a plutonic cu mu late rock, and we fol low the pro posal of Gunia et al (1998), that the rock is sup pos edly an ultra mafic cu mu late formed in an is land arc root. The cumulates formed in vol ca nic arc roots show strongly vari able com po sitions, both in terms of min eral and bulk-rock chem i cal com po sition, which is a func tion of the fractionating magma's start ing com po si tion, its wa ter con tent, and ox y gen fugacity, and of the pres sure and tem per a ture of crystallisation (see the data in e.g., Greene et al, 2006;Dhuime et al, 2009;Chen et al, 2009).…”