Proterozoic anorogenic two-mica granites: Silver Plume and St. Vrain batholiths of Colorado

Anderson, J. Lawford; Thomas, Warren M.

doi:10.1130/0091-7613(1985)13<177:patgsp>2.0.co;2

Cited by 74 publications

(29 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, it has long been recognized (e.g., Hanson and Al-Shaieb 1980;Anderson and Thomas 1985) that subalkaline or even peraluminous silicic igneous rocks are not restricted to volcanic arcs formed at convergent plate boundaries, but also occur in rifting environments and form a distinct group of anorogenic granitoids. Alkaline A-type granitoids could be generated by the partial melting of lower crustal lithologies (felsic granulites), which suffered depletion through earlier melt extraction (Collins et al 1982;Clemens et al 1986), or merely H 2 O loss during a metamorphic event (Skjerlie and Johnson 1992).…”

Section: Discussionmentioning

confidence: 99%

Early Palaeozoic crustal melting in an extensional setting: petrological and Sm–Nd evidence from the Izera granite-gneisses, Polish Sudetes

Oberc-Dziedzic

Kryza

2005

Int J Earth Sci (Geol Rundsch)

View full text Add to dashboard Cite

The Izera Block in the West Sudetes, which is composed of granites, gneisses (and transitional granitegneisses) and minor mica schists, is one of the largest outcrops of Early Palaeozoic (ca. 500 Ma) metagranitoid rocks in the basement units of the Variscides of Central Europe. The Izera granites show S-type features: magmatic cordierite, relict garnet and sillimanite, lack of mafic enclaves, and absence of coexisting tonalites and diorites. The paucity of pegmatites indicates that the granitic magma was relatively dry. The S-type character of these granites is further supported by their peraluminous character (A/CNK 1.0-1.63), high content of normative corundum (up to 3.5%) and relatively high 87 Sr / 86 Sr initial ratio. The chemical variation of these rocks was controlled by the fractional crystallization of plagioclase (CaO, Sr, Eu/Eu*), biotite and cordierite (Al 2 O 3 , MgO, FeO), zircon (Zr, Hf) and monazite (REE). Initial Nd values range from À5.2 to À6.9 (mean: À5.9, SD=0.6). These largely negative Nd values imply that the granitic magmas emplaced ca. 500 Ma were extracted from a source reservoir that was strongly enriched in LREE (i.e., with low Sm/Nd ratio) on a time-integrated basis. The relatively consistent depleted mantle model ages (1,730-2,175 Ma; mean: 1,890 Ma) is in agreement with the earlier reported presence of ca. 2.1 Ga old inherited Pb component in zircon from the closely related Rumburk granite. This points to an old (Early Proterozoic) crustal residence age of the inferred metasedimentary protoliths of the Izera granitoids, with only minor contribution to their protoliths of juvenile components of Late Proterozoic/Early Palaeozoic age. Although the Izera granites show some trace element features reminiscent of syn-collisional or post-collisional granitoids, they more likely belong to the broad anorogenic class. Our data corroborate some previous interpretations that granite generation was connected with the Early Palaeozoic rifting of the passive margin of the Saxothuringian block, well documented in the region by bimodal volcanic suites of similar age (Kaczawa Unit, eastern and southern envelope of the Karkonosze-Izera Block). In this scenario, granite magmatism and bimodal volcanism would represent two broadly concomitant effects of a single major event of lithospheric break-up at the northern edge of Gondwana.

show abstract

Section: Discussionmentioning

confidence: 99%

Early Palaeozoic crustal melting in an extensional setting: petrological and Sm–Nd evidence from the Izera granite-gneisses, Polish Sudetes

Oberc-Dziedzic

Kryza

2005

Int J Earth Sci (Geol Rundsch)

View full text Add to dashboard Cite

show abstract

“…For the genesis of aluminous A-type granites, King et al [62] considered that it came from partial melting of felsic lower crust with normal H 2 O contents. Poitrasson et al [63,64] also proposed that the aluminous A-type granite came from partial melting of lower crust material, but considered that the source component was predominantly mafic; whereas Anderson et al [65] considered that aluminous A-type granite came from partial melting of peraluminous sedimentary rocks in the lower crust. The basement of the Yangtze Craton where the Taiping-Huangshan composite intrusion is located includes high-grade metamorphic crystalline rocks and low-grade metamorphic folded rocks.…”

Section: Rock Genesismentioning

confidence: 96%

“…Generally, A-type granites include alkaline granite with alkaline supersaturated and aluminous A-type granite [62][63][64][65] . The Huangshan intrusion is classified geochemically as aluminous A-type granite.…”

Section: Rock Genesismentioning

confidence: 99%

Zircon U-Pb SHRIMP ages of the Taiping (calc-alkaline)-Huangshan (alkaline) composite intrusion: Constraints on Mesozoic lithospheric thinning of the southeastern Yangtze Craton, China

Xue

Ying-geng

et al. 2009

Sci. China Ser. D-Earth Sci.

View full text Add to dashboard Cite

The Taiping-Huangshan composite intrusion is a unique complex with characteristics changing from calc-alkaline (Taiping intrusion) to alkaline (Huangshan intrusion). Huangshan intrusion samples show a spectacular tetrad effect in their REE distribution patterns as well as non-CHARAC (charge-andradius-controlled) trace element behavior, indicating a highly evolved late-stage magma component. This composite intrusion provides a rare opportunity to investigate the variance of tectonic setting and lithospheric thinning of the southeastern Yangtze Craton in lateMesozoic era. Zircon SHRIMP U-Pb analyses yield an emplacement age of 140.6±1.2 Ma for the Taiping intrusion, and ages of 127.7±1.3, 125.7±1.4, 125.1±1.5, and 125.2±5.5 Ma for four samples from the Huangshan intrusion respectively. The ages for four different phases of the Huangshan intrusion agree within their small analytical errors, indicating that the emplacement was in a short time. The Taiping and Huangshan intrusions are intimately associated, but there is about 15 Ma interval between their intrusion, and the magma characters change from calc-alkaline to alkaline without transition. This probably corresponds to lithospheric thinning of the southeastern Yangtze Craton. This event possibly happened from about 141 Ma (the emplacement age of the Taiping intrusion), to 128 Ma (start of emplacement of the Huangshan intrusion). The thinning mechanism is dominantly delamination.

show abstract

“…The 1.4-Ga intrusive rocks are represented by the peraluminous St. Kevin Granite and possibly by the age-equivalent Silver Plume Granite. This plutonic event was largely anorogenic, and the melts were derived from metasedimentary rocks in the lower crust (Anderson and Thomas, 1985).…”

Section: Rocksmentioning

confidence: 99%

Isotopic geochronology of the Leadville 1° x 2° quadrangle, west-central Colorado; summary and discussion

Wallace¹

1995

View full text Add to dashboard Cite

Proterozoic anorogenic two-mica granites: Silver Plume and St. Vrain batholiths of Colorado

Cited by 74 publications

References 0 publications

Early Palaeozoic crustal melting in an extensional setting: petrological and Sm–Nd evidence from the Izera granite-gneisses, Polish Sudetes

Early Palaeozoic crustal melting in an extensional setting: petrological and Sm–Nd evidence from the Izera granite-gneisses, Polish Sudetes

Zircon U-Pb SHRIMP ages of the Taiping (calc-alkaline)-Huangshan (alkaline) composite intrusion: Constraints on Mesozoic lithospheric thinning of the southeastern Yangtze Craton, China

Isotopic geochronology of the Leadville 1° x 2° quadrangle, west-central Colorado; summary and discussion

Contact Info

Product

Resources

About