‘Subduction Style’ Magmatism in a Non-subduction Setting: the Colville Igneous Complex, NE Washington State, USA

Morris, G. A.; Larson, Peter B.; Hooper, P. R.

doi:10.1093/petrology/41.1.43

Cited by 83 publications

(35 citation statements)

References 41 publications

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“…In this respect these rocks are similar to other calcalkaline rocks that occur in the Great Basin (Barr, 1993). However, recent work on the Colville igneous complex in northeastern Washington by Morris et al (2000) questions the assumption that calcalkaline rocks such as these are derived from subduction-zone processes. Their conclusion is based on key major-, trace-, and rare earth element data that are not consistent with large-scale fractionation that would be required to produce the compositional variation observed in the Colville igneous complex.…”

Section: Petrochemistry Of the Stocksmentioning

confidence: 99%

Origin and emplacement of igneous rocks in the central Wasatch Mountains, Utah

Vogel

Cambray

Constenius

2001

Rocky Mountain Geology

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The calc-alkaline igneous rocks in the central Wasatch Mountains were emplaced between 36-30 Ma. They form a belt comprised of eleven stocks and the Keetley volcanic field aligned along the crustal suture between the Archean Wyoming province and accreted Paleoproterozoic terranes. Magmatism associated with this belt and its westward continuation into the Bingham mining district has been related to midCenozoic extension. These rocks consist of two types of stocks based on texture: a western type, which is coarse grained, and mostly equigranular, and an eastern type (including the Keetley volcanic rocks), which is fine grained and porphyritic. The compositional variation in the western stocks (Little Cottonwood, Alta, and Clayton Peak stocks) forms three distinct compositional groups. The compositional variation in the eastern stocks is similar to the compositional variation in the Alta stock. Major and trace element variations in these rocks resemble those of subduction-related magmas. However, the high KzO contents and low values are not consistent with this origin. These magmas formed from melting of mafic igneous rocks. We propose that magmas were generated by decompression melting due to gravitational collapse of the crust that had been thickened during Cretaceous to early Cenozoic deformation. Magmas rose to varying levels in the crust along a n east-west lineament. The igneous rocks of the central Wasatch Mountains have E~~(~~ similar to most of the Phanerozoic igneous rocks in the miogeocline (MG), but have significantly lower E ,~(~) .That anomaly has been explained as due to melting of a basement long depleted in Rb (Farmer andDePaolo, 1983, 1984). However, the Wasatch igneous belt rocks are high-potassium, calc-alkaline rocks and all have very similar incompatible trace element patterns, whereas only a few MG rocks are calc-alkaline or high potassium. Furthermore, in the MG rocks incompatible trace element patterns are variable. One possible explanation for the dilemma of long-time depletion of Rb in these high-potassium, calc-alkaline rocks is that the crust may have been recently charged with Rb and K during the Sevier-Laramide event (100-40 Ma) by dehydration of the subducting slab. This event was followed by melting during mid-Cenozoic collapse of the orogen (ca. 40-20 Ma). The source of the magmas was melting of mafic rocks in the lower crust. Some of these magmas ponded, formed magma chambers, and differentiated. Some involved little ponding and erupted directly on the surface in the form of the Keetley volcanic field. Continued melting and extension produced new magmas from a similar crustal source. These magmas were emplaced below a series of pull-apart structures associated with strike-slip displacement along an east-west suture. This suture may have been controlled by the ArcheanProterozoic boundary. Some magma bodies were emplaced quickly to the surface without significant fractionation. Others coalesced and fractionated over a protracted period of time. These magma bodies interacted with crus...

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Section: Petrochemistry Of the Stocksmentioning

confidence: 99%

Origin and emplacement of igneous rocks in the central Wasatch Mountains, Utah

Vogel

Cambray

Constenius

2001

Rocky Mountain Geology

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“…They suggested that trace element characteristics of the andesites and dacites from the Erciyes are similar to Colville igneous complex (Washington, USA), Central Mexican Volcanic Belt and Taos volcanic field (New Mexico, USA). Partial melting of heterogenous lower crust or decompression melting of crust and mantle were proposed for the magma generation in these igneous provinces (Verma 1999; Morris et al 2000). The geochemical characteristics so as to reflect both crust and mantle origin are also more akin to characteristics for metasomatized mantle by fluids derived from a subducted slab.…”

Section: Implications For Cavp Volcanismmentioning

confidence: 99%

Geochemical characterization of a Quaternary monogenetic volcano in Erciyes Volcanic Complex: Cora Maar (Central Anatolian Volcanic Province, Turkey)

Gençalioğlu-Kuşcu

2010

Int J Earth Sci (Geol Rundsch)

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“…In the case of the Colville Igneous Complex (NE Washington State, USA), the calc-alkaline magmatic rocks show an affinity with the geochemical signatures of orogenic magmas from subduction zones (Morris et al, 2000), such as the calc-alkaline rocks of the WAA (Fig. 8).…”

Section: Comparison With Other Examples Of Calc-alkaline Magmatismmentioning

confidence: 99%

“…MORB-normalized spiderdiagrams of the calc-alkaline mafic rocks from Igherm, Ifni and Kerdous inliers(Pearce, 1982) compared to the mafic calc-alkaline magmatism from the Colville Igneous Complex (NE Washington State, USA) afterMorris et al (2000).…”

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confidence: 99%