Structure, Construction, and Geochemistry of the Cretaceous Seven-Fingered-Jack Intrusive Complex in the Klone Peak Area, North Cascades, Washington

1999 ◽

pp. 103-112

Author(s):

Feiko Kalsbeek ◽

Lilian Skjernaa

Keyword(s):

Intrusive Complex ◽

The South ◽

Original Series ◽

Early Proterozoic ◽

West Greenland ◽

North East ◽

The North ◽

Southern Border ◽

Area North ◽

Igneous Layering

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Kalsbeek, F., & Skjernaa, L. (1999). The Archaean Atâ intrusive complex (Atâ tonalite), north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 103-112. https://doi.org/10.34194/ggub.v181.5118 _______________ The 2800 Ma Atâ intrusive complex (elsewhere referred to as ‘Atâ granite’ or ‘Atâ tonalite’), which occupies an area of c. 400 km2 in the area north-east of Disko Bugt, was emplaced into grey migmatitic gneisses and supracrustal rocks. At its southern border the Atâ complex is cut by younger granites. The complex is divided by a belt of supracrustal rocks into a western, mainly tonalitic part, and an eastern part consisting mainly of granodiorite and trondhjemite. The ‘eastern complex’ is a classical pluton. It is little deformed in its central part, displaying well-preserved igneous layering and local orbicular textures. Near its intrusive contact with the overlying supracrustal rocks the rocks become foliated, with foliation parallel to the contact. The Atâ intrusive complex has escaped much of the later Archaean and early Proterozoic deformation and metamorphism that characterises the gneisses to the north and to the south; it belongs to the best-preserved Archaean tonalite-trondhjemite-granodiorite intrusions in Greenland.

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U-PB ZIRCON AGE OF DYKES IN THE ROOF OF THE BLACK PEAK INTRUSIVE COMPLEX, NORTH CASCADES

10.1130/abs/2017cd-292733 ◽

2017 ◽

Author(s):

Robert Cruze ◽

◽

Adam J.R. Kent ◽

Robert B. Miller ◽

Erin Shea

Keyword(s):

Intrusive Complex ◽

North Cascades ◽

Zircon Age

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On batholiths and volcanoes - intrusion and eruption of late Cenozoic magmas in the Glacier Peak area, North Cascades, Washington

Professional Paper ◽

10.3133/pp604 ◽

1969 ◽

Cited By ~ 5

Author(s):

R.W. Tabor ◽

D.F. Crowder

Keyword(s):

Late Cenozoic ◽

North Cascades ◽

Area North

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Stable isotope compositions of olivine and dolomite in peridotites formed by deserpentinization, Darrington area, North Cascades, Washington

Geochimica et Cosmochimica Acta ◽

10.1016/0016-7037(77)90272-1 ◽

1977 ◽

Vol 41 (3) ◽

pp. 431-435

Author(s):

Michael Johnson ◽

Michael A Dungan ◽

Joseph A Vance

Keyword(s):

Stable Isotope ◽

North Cascades ◽

Area North

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SHRIMP U-Pb zircon ages for Archaean granitoid rocks, Ataa area, north-east Disko Bugt, West Greenland

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v181.5111 ◽

1999 ◽

pp. 49-54

Author(s):

Allen P. Nutman ◽

Feiko Kalsbeek

Keyword(s):

Field Observations ◽

Intrusive Complex ◽

Ion Microprobe ◽

Granitoid Rock ◽

Original Series ◽

West Greenland ◽

North East ◽

Granitoid Rocks ◽

Area North ◽

Age Determinations

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Nutman, A. P., & Kalsbeek, F. (1999). SHRIMP U-Pb zircon ages for Archaean granitoid rocks, Ataa area, north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 49-54. https://doi.org/10.34194/ggub.v181.5111 _______________ Zircons from four samples of granitoid rocks from the Ataa area have been studied by SHRIMP ion microprobe. A trondhjemite from the Atâ intrusive complex (Atâ tonalite) yielded an age of 2803 ± 4 Ma, in agreement with earlier age determinations. A sample from the regional migmatitic biotite gneisses gave 2815 ± 4 Ma. A homogeneous granitoid rock, from ﬁeld observations believed to be younger than the regional gneisses, has two main zircon populations, 2835 ± 4 Ma and c. 2800 Ma, respectively, and a granite that intrudes the Atâ complex yielded an age of 2758 ± 2 Ma.

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