Geology

Rift

Metamorphism

Geochemistry

Terrane

Paleontology

Metamorphic rock

Tectonics

American Mineralogist

Other| December 01, 1997 High-grade contact metamorphism of calcareous rocks from the Oslo Rift, Southern Norway Bjorn Jamtveit; Bjorn Jamtveit University of Oslo, Department of Geology, Oslo, Norway Search for other works by this author on: GSW Google Scholar Sven Dahlgren; Sven Dahlgren Norwegian Petroleum Directorate, Norway Search for other works by this author on: GSW Google Scholar Haakon Austrheim Haakon Austrheim Mineralogical-Geological Museum, Norway Search for other works by this author on: GSW Google Scholar American Mineralogist (1997) 82 (11-12): 1241–1254. https://doi.org/10.2138/am-1997-11-1219 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Bjorn Jamtveit, Sven Dahlgren, Haakon Austrheim; High-grade contact metamorphism of calcareous rocks from the Oslo Rift, Southern Norway. American Mineralogist 1997;; 82 (11-12): 1241–1254. doi: https://doi.org/10.2138/am-1997-11-1219 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract Shallow-level plutons caused extensive contact metamorphism of Lower Paleozoic shale and carbonate sequences in the Permian Oslo Rift. A >500 m long and 100 m wide shale-limestone xenolith embedded within monzonites belonging to the Skrim plutonic complex experienced high-grade contact metamorphism and generation of minerals and mineral assemblages rarely reported from metamorphic rocks. The peak metamorphic (Stage I) assemblages in calcite-saturated rocks include wollastonite, melilites, fassaitic pyroxenes, phlogopite, titanian grossular, kalsilite, nepheline, perovskite, cuspidine, baghdadite, pyrrhotite, and occasional graphite. Mineral reactions involving detrital apatite produced a series of silicate apatites, including the new mineral species Ca3.5(Th,U)1.5Si3O12(OH). This assemblage equilibrated at T = 820–870 °C with a C-rich, internally buffered pore-fluid (20–40 mol% CO2 + CH4). During cooling the shale-limestone xenolith experienced infiltration of C-poor (< 0.1 mol% CO2) fluids, triggering the formation of retrograde (Stage II) mineral assemblages comprising monticellite, tilleyite, vesuvianite, grandite garnets, diopside, and occasional hillebrandite. Rare potassium iron sulfides (rasvumite and djerfisherite) formed at the expense of primary pyrrhotite. These assemblages probably formed near 700 °C. Formation of diffuse sodalite-bearing veinlets was associated with breakdown of nepheline and the replacement of kalsilite and wollastonite by potassium feldspar. The sodalite-bearing Stage III assemblage formed by the infiltration of saline brines at a maximum temperature of 550 °C. Low-temperature (Stage IV) retrogression of the Stage I-III assemblage produced scawtite, giuseppettite, hydrogrossulars, phillipsite, thomsonite, and three hitherto undescribed mineral species. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

High-grade contact metamorphism of calcareous rocks from the Oslo Rift, Southern Norway