A 2.5 G.a. reworked sialic crust: Rb-Sr ages and isotopic geochemistry of late archaean volcanic and plutonic rocks from E. Finland

1984 ◽  
Vol 85 (3) ◽  
pp. 292-299 ◽  
Author(s):  
Herv� Martin ◽  
Guirec Querr�
Keyword(s):  
Late Archaean ◽  
Sialic Crust ◽  
Isotopic Geochemistry ◽  
Plutonic Rocks

Isotopic assessment of relative contributions from crust and mantle sources to the magma genesis of Precambrian granitoid rocks

1984 ◽  
Vol 310 (1514) ◽  
pp. 605-625 ◽  
Keyword(s):  
Calc Alkaline ◽  
Isotopic Data ◽  
Late Archaean ◽  
Magma Genesis ◽  
West Greenland ◽  
Sialic Crust ◽  
Mantle Sources ◽  
Granitoid Rocks ◽  
Plutonic Rocks ◽  
Source Materials

Rb-Sr, Sm-Nd and U-Th-Pb isotopic data for Precambrian granitoids (i.e. granites and intermediate calc-alkaline plutonic rocks) from Greenland, Scotland and Zimbabwe are used to assess the relative contributions to magma genesis of various source materials. Ancient continental crustal contributions are identified by negative e N d values in the magmas at time of formation. Initial 87 Sr/ 86 Sr (Sr 1 ,) values identify crustal contributions as derived from deep (low Rb/Sr) or upper (high Rb/Sr) crust. Pb isotopic data, expressed as model ( 238 U / 204 Pb) values, permit the distinction between deep (low U/Pb) and upper (high U/Pb) crustal contributions. However, it is not usually possible to distinguish between mantle (low Rb/Sr) and deep crustal sources using Sr 1 values. In contrast, Nd and Pb isotopic data permit such a distinction to be made. The granitoids isotopically analysed for the present study range from calc-alkaline types with mantle or mixed mantle-crust isotopic characteristics (for example, late Archaean orthogneisses from west Greenland) to true granites probably produced solely by anatexis of ancient sialic crust (for example, Badcall Quay red granite, northwest Scotland; Qorqut granite, west Greenland; Mont d’Or granite, Zimbabwe).

K-Ar ages of the metamorphic and plutonic rocks in the southern part of the Hidaka belt, Hokkaido and their implications.

1995 ◽  
Vol 90 (9) ◽  
pp. 297-309 ◽  
Author(s):  
Keisuke SAHEKI ◽  
Masatoshi SHIBA ◽  
Tetsumaru ITAYA ◽  
Hitoshi ONUKI
Keyword(s):  
Plutonic Rocks

Laramide to Miocene syn-extensional plutonism in the Puerta del Sol area, central Sonora, Mexico

2017 ◽  
Vol 34 (1) ◽  
pp. 45 ◽  
Author(s):  
Elizard González-Becuar ◽  
Efrén Pérez-Segura ◽  
Ricardo Vega-Granillo ◽  
Luigi Solari ◽  
Carlos Manuel González-León ◽  
...  
Keyword(s):  
Metamorphic Core Complex ◽  
Primitive Mantle ◽  
Isotopic Ratios ◽  
Magmatic Evolution ◽  
Calc Alkaline ◽  
Core Complex ◽  
High K ◽  
Sierra Madre ◽  
Plutonic Rocks ◽  
Metamorphic Core

Plutonic rocks of the Puerta del Sol area, in central Sonora, represent the extension to the south of the El Jaralito batholith, and are part of the footwall of the Sierra Mazatán metamorphic core complex, whose low-angle detachment fault bounds the outcrops of plutonic rocks to the west. Plutons in the area record the magmatic evolution of the Laramide arc and the Oligo-Miocene syn-extensional plutonism in Sonora. The basement of the area is composed by the ca. 1.68 Ga El Palofierral orthogneiss that is part of the Caborca block. The Laramide plutons include the El Gato diorite (71.29 ± 0.45 Ma, U-Pb), the El Pajarito granite (67.9 ± 0.43 Ma, U-Pb), and the Puerta del Sol granodiorite (49.1 ± 0.46 Ma, U-Pb). The younger El Oquimonis granite (41.78 ± 0.32 Ma, U-Pb) is considered part of the scarce magmatism that in Sonora records a transition to the Sierra Madre Occidental magmatic event. The syn-extensional plutons are the El Garambullo gabbro (19.83 ± 0.18 Ma, U-Pb) and the Las Mayitas granodiorite (19.2 ± 1.2 Ma, K-Ar). A migmatitic event that affected the El Palofierral orthogneiss, El Gato diorite, and El Pajarito granite between ca. 68 and 59 Ma might be related to the emplacement of the El Pajarito granite. The plutons are metaluminous to slightly peraluminous, with the exception of El Oquimonis granite, which is a peraluminous two-mica, garnet-bearing granite. They are mostly high-K calc-alkaline with nearly uniform chondrite-normalized REE and primitive-mantle normalized multielemental patterns that are characteristic of continental margin arcs and resemble patterns reported for other Laramide granites of Sonora. The Laramide and syn-extensional plutons also have Sr, Nd and Pb isotopic ratios that plot within the fields reported for Laramide granites emplaced in the Caborca terrane in northwestern and central Sonora. Nevertheless, and despite their geochemical affinity to continental magmatic arcs, the El Garambullo gabbro and Las Mayitas granodiorite are syn-extensional plutons that were emplaced at ca. 20 Ma during development of the Sierra Mazatán metamorphic core complex. The 40Ar/39Ar and K-Ar ages obtained for the El Palofierral orthogneiss, the Puerta del Sol granodiorite, the El Oquimonis granite, and the El Garambullo gabbro range from 26.3 ± 0.6 to 17.4 ± 1.0 Ma and are considered cooling ages associated with the exhumation of the metamorphic core complex.

Elemental and isotopic geochemistry of nonhydrated quartz latite glasses from the Eureka Valley Tuff, east-central California

1976 ◽  
Vol 87 (5) ◽  
pp. 754 ◽  
Author(s):  
DONALD C. NOBLE ◽  
MARJORIE K. KORRINGA ◽  
S. E. CHURCH ◽  
HARRY R. BOWMAN ◽  
MILES L. SILBERMAN ◽  
...  
Keyword(s):  
East Central ◽  
Central California ◽  
Isotopic Geochemistry

MINERAL GEOCHEMISTRY OF CRETACEOUS AND EOCENE PLUTONIC ROCKS FROM THE OKANOGAN HIGHLANDS, NORTHEASTERN WASHINGTON STATE

2020 ◽  
Author(s):  
Katherine D. Arnett ◽  
◽  
Theo M. Hannon ◽  
James H. MacDonald ◽  
Jeffrey H. Tepper
Keyword(s):  
Washington State ◽  
Plutonic Rocks
Sign in / Sign up

Export Citation Format

Share Document