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TitleMagnesium isotopes in high-temperature saddle dolomite cements in the lower Paleozoic of Canada
 
AuthorLavoie, DORCID logo; Jackson, SORCID logo; Girard, IORCID logo
SourceSedimentary Geology vol. 305, 2014 p. 58-68, https://doi.org/10.1016/j.sedgeo.2014.03.002
Image
Year2014
Alt SeriesEarth Sciences Sector, Contribution Series 20120311
PublisherElsevier BV
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia; Alberta; Saskatchewan; Manitoba; Ontario; Quebec; New Brunswick; Nova Scotia; Prince Edward Island; Newfoundland and Labrador; Northwest Territories; Yukon; Nunavut; Canada
NTS1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65; 66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560
Subjectssedimentology; dolomites; magnesium; isotopes; hydrothermal deposits; dolomitization; petrography; Paleozoic
Illustrationslocation maps; photomicrographs; tables; plots
ProgramGEM: Geo-mapping for Energy and Minerals Hudson / Foxe Bay Sedimentary Basins
AbstractMg isotopes are used to better understand the genesis of hydrothermal saddle dolomite cements in Lower Paleozoic successions in Canada. These cements occur in fault-bounded dolostones that overlay lithologically diverse basement rocks; Ordovician dolomite lies over the Precambrian craton,whereas the Silurian and Devonian dolomites overlay a succession of tectonically accreted sedimentary, volcanic and ultramafic units of Cambrian to Ordovician age. Lower Silurian saddle dolomites have the most negative d26MgDSM3 values of our dataset (-3.25 to -1.13permil), and plot in two distinct groups: a strongly negative subset that characterizes higher temperature (175 °C) dolomites, and a less negative subset for lower temperature (153 °C) dolomites. Upper Ordovician saddle dolomites precipitated at significantly lower temperatures (102 °C), and their d26MgDSM3 values range from -1.26 to -0.71permil. Lower Devonian saddle dolomites formed at very high temperature (350 °C) and have d26MgDSM3 values ranging from -1.29 to -0.78permil. No experimental data on high temperature (100-350 °C) fluid-dolomite Mg isotope fractionation factors have been published, and recent research suggests that no significant fractionation occurs between diagenetic fluids and dolomites at high temperatures in closed to semi-closed diagenetic systems. Our results indicate that the isotopic signature of diagenetic fluid is the primary control for the d26MgDSM3 values in these high-temperature dolomites.
GEOSCAN ID292057

 
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