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| Titel |
Surface heat flow of southern Israel based on new borehole data |
| VerfasserIn |
F. Schütz, A. Forster |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250067029
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| Zusammenfassung |
| In the framework of the international DESIRE project new surface heat-flow values were
determined at ten borehole locations in southern Israel. Maximum accessible depth for
temperature borehole logging was 800 m. The section studied comprises sedimentary rocks
of Aptian to Eocene age. Boreholes, in which new temperature logs were obtained, are well
distributed across southern Israel allowing the observation of a regional heat-flow trend.
New values of thermal conductivity, porosity and density, measured on drillcore
and surface samples, formed the petrophysical database for the study. Thermal
conductivity was measured under dry and water-saturated conditions for lithotypes and
scaled up for geological formations. The new values are higher than most of the
previously measured values, in particular for sandstones and siltstones, whose mean
values are 5.0 and 2.9 W m-1 K-1, respectively. Mean thermal conductivities of the
most abundant lithotypes, which are dolomites and limestones, are on the order of
4.1 and 2.7 W m-1 K-1, respectively. The total radiogenic heat production of the
sedimentary cover, determined from gamma ray logs, varies slightly at regional scale
providing a heat flow of < 4 mW m-2 for the sections above the Precambrian and
Pan-African basement. Surface heat flow, calculated from continuous temperature
logs using the interval method, ranges from 50-62 mW m-2 . The values plot
in the upper half of previously determined values (40-60 mW m-2 ) and are in
accordance with values recently determined east of the Dead Sea Transform (DST)
in Jordan. A weak trend of decreasing surface heat flow from the DST towards
the Mediterranean Sea can be identified. This trend can be explained by regional
changes in structure and mean composition of the lithosphere that are known from
DESERT and DESIRE refraction seismic surveys and are quantified by a lithospheric
2D thermal model. Thus the thermal model provides a substantiated insight into
the scale of heat-flow variations of the stable lithosphere in the greater DST area. |
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