Organic Matter and Clay Minerals at the Polaris Zn-Pb Deposit, Canadian Arctic Archipelago

1996 ◽  
pp. 320-329
Keyword(s):  
Organic Matter ◽  
Clay Minerals ◽  
Canadian Arctic ◽  
Canadian Arctic Archipelago

scholarly journals Pleistocene organic matter modified by the Hiawatha impact, northwest Greenland

Geology ◽  
2020 ◽  
Vol 48 (9) ◽  
pp. 867-871 ◽  
Author(s):  
Adam A. Garde ◽  
Anne Sofie Søndergaard ◽  
Carsten Guvad ◽  
Jette Dahl-Møller ◽  
Gernot Nehrke ◽  
...  
Keyword(s):  
Organic Matter ◽  
Impact Crater ◽  
Canadian Arctic ◽  
Early Pleistocene ◽  
Sand Sample ◽  
Canadian Arctic Archipelago ◽  
Outwash Plain ◽  
The Impact ◽  
Firm Evidence ◽  
North Greenland

Abstract The 31-km-wide Hiawatha impact crater was recently discovered under the ice sheet in northwest Greenland, but its age remains uncertain. Here we investigate solid organic matter found at the tip of the Hiawatha Glacier to determine its thermal degradation, provenance, and age, and hence a maximum age of the impact. Impactite grains of microbrecchia and shock-melted glass in glaciofluvial sand contain abundant dispersed carbon, and gravel-sized charcoal particles are common on the outwash plain in front of the crater. The organic matter is depleted in the thermally sensitive, labile bio-macromolecule proto-hydrocarbons. Pebble-sized lumps of lignite collected close to the sand sample consist largely of fragments of conifers such as Pinus or Picea, with greatly expanded cork cells and desiccation cracks which suggest rapid, heat-induced expansion and contraction. Pinus and Picea are today extinct from North Greenland but are known from late Pliocene deposits in the Canadian Arctic Archipelago and early Pleistocene deposits at Kap København in eastern North Greenland. The thermally degraded organic material yields a maximum age for the impact, providing the first firm evidence that the Hiawatha crater is the youngest known large impact structure on Earth.

Particle Size Effects on Concentration of Metals in Lake Erie Bottom Sediments

1984 ◽  
Vol 19 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Alena Mudroch
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Clay Minerals ◽  
Surface Sediment ◽  
Size Effects ◽  
Lake Erie ◽  
Size Fraction ◽  
Mineralogical Composition ◽  
Major Elements ◽  
Sediment Samples

Abstract Surface sediment samples obtained at the offshore and nearshore area of Lake Erie were separated into eight different size fractions ranging from <2 µm to 250 µm. The concentration of major elements (Si, Al, Ca, Mg, K, Na, Fe, Mn and P), metals (Zn, Cu, Cr, Ni, V, Co and Pb) and organic matter was determined together with the mineralogical composition and morphology of the particles in each size fraction. The distribution of the metals in the offshore sediment was bimodal with the majority of the metals divided between the 63 to 250 um size fraction which also contained the highest concentration of organic matter (about 20%) and the <4 µm fraction containing up to 60% of clay minerals. However, the metals in the nearshore sediment were associated mainly with the clay minerals.

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