Estrada, Solveig; Höhndorf, Axel; Henjes-Kunst, Friedhelm (2001): Tab. 1: Geochemical analysis and age dating of Kap Washington Group volcanites and related dykes. PANGAEA, doi:10.1594/PANGAEA.107284, Supplement to: Estrada, S et al. (2001): Cretaceous/Tertiary volcanism in North Greenland: the Kap Washington Group. Polarforschung, 69, 17-23, hdl:10013/epic.29823.d001
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The bimodal, alkaline volcanic suite of the Kap Washington Group (KWG) at the northern coast of Greenland was investigated during the BGR CASE 2 expedition in 1994. Geochemical and Nd and Sr isotopic data are presented for basalts to rhyolites of the KWG and of related basaltic dykes cutting Lower Paleozoic sediments. In the evd(t) vs. (87Sr/86Sr)t diagram, the KWG basalts and rhyolites follow a common mixing trend with increasing crustal contamination from basic to acid volcanites. Assimilation of pre-existing crustal rocks during formation of the rhyolitic melt is documented by Nd model ages of 0.9-1.2 Ga and by different fractionation trends for the basalts and the rhyolites in the Y vs. Zr diagram. Petrographical and geochemical features indicate intra-plate volcanism which was active most probably during a continental rifting phase. A new Rb/Sr whole rock age on rhyolites of 64 ±3 Ma, corresponding to the result of LARSEN (1982), confirms that the volcanic activity lasted until the Cretaceous-Tertiary boundary. 40Ar139Ar dating on amphibol separates from a comendite yielded strongly disturbed age spectra with a minimum age of 37.7 ±0.3 Ma. This age is interpreted to date a hydrothermal overprint of the volcanic rocks related to compressive tectonics which led to the overthrust of basement rocks over the Kap Washington Group.
Latitude: 83.000000 * Longitude: -40.000000
Minimum Elevation: 0.0 m * Maximum Elevation: 0.0 m
Sr and Nd were seperated from 50-100 mg of powder using standard ion exchange techniques and analysed as metal species on a MAT261 multicollector mass spectrometer in static mode.
|#||Name||Short Name||Unit||Principal Investigator||Method||Comment|
|1||Sample code/label||Sample label||Estrada, Solveig|
|2||Lithology/composition/facies||Lithology||Estrada, Solveig||Smear slide analysis|
|4||Rubidium||Rb||mg/kg||Estrada, Solveig||X-ray fluorescence (XRF)|
|5||Strontium||Sr||mg/kg||Estrada, Solveig||ICP-AES, Inductively coupled plasma - atomic emission spectroscopy|
|6||Rubidium 87/Strontium 86 ratio||87Rb/86Sr||Estrada, Solveig||95% confidence level is +-2%|
|7||Strontium 87/Strontium 86 ratio||87Sr/86Sr||Estrada, Solveig||95% confidence level is +-0.06%|
|8||Strontium 87/Strontium 86 ratio||87Sr/86Sr||Estrada, Solveig||87Sr/86Sr - 64Ma|
|11||Samarium 147/Neodymium 144 ratio||147Sm/144Nd||Estrada, Solveig||Calculated|
|12||Neodymium 143/Neodymium 144||143Nd/144Nd||Estrada, Solveig||95% confidence level is +-0.014%|
|13||epsilon-Neodymium||e-Nd||Estrada, Solveig||Calculated||eNd - 64 Ma|
|14||Age, dated||Age dated||ka||Estrada, Solveig||Age, 87Rb/87Sr Rubidium-Strontium||T DM calc. according to 2-stage model of DePaolo et al. 1991|
454 data points