Surface heat flow measurements in Lake Vättern and along the continental slope of the East Siberian Sea

Pedro Preto Department of Geological SciencesMay 3 2016
10h00 , Nordenskiöldsalen
Licenciate Defense by Pedro Preto

 

Heat flow is a measure commonly used to understand the internal and surface processes of the Earth. Here two examples are presented of how heat flow can be applied to study near surface processes in marine and lacustrine settings. The study locations are southern Lake Vättern, Sweden, and along the East Siberian continental margin of the Arctic Ocean. Both areas are underlain by continental lithosphere. The ocean dataset was collected using 21 shallow measurements and the setting was constrained by the use of a single deep borehole profile. The research required accompanying analyses of the physical and thermal properties of sediments. The former were measured using a Multi-Sensor Core Logger and helium displacement pycnometer, while the second were obtained using a Hot Disk thermal properties measurement system manufactured by K-analysis. In-situ temperature measurements were obtained using miniature temperature probes. Heat flow calculated in southern Lake Vättern was 40.6 ± 5.0 mW/m2, while the average surface heat flow in the region of the East Siberian continental slope was 57 ± 10 mW/m2, excluding an anomalously high heat flow obtained in Herald Canyon (102 ± 11 mW/m2). The results show how local environmental factors can affect the geothermal gradient and, therefore, surface heat flow. In southern Lake Vättern, the heat flow data was used to identify an active fluid flow system within glaciofluvial and glaciolacustrine sediments overlying a well-documented sandstone groundwater aquifer. In the Western Arctic, the heat flow data fills a tremendous data-gap in a region where few published measurements exist and was used, in a parallel modelling study, to determine the thickness of the gas hydrate stability zone (GHSZ) and its susceptibility to warming bottom water conditions. It can be further used to investigate tectonic controls on regional heat flow variations in a poorly understood geological region of the World Ocean’s.

 

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