Lithospheric Heat Flow and Isostacy

Annette Fugl
123D Technology, Odense, Denmark

The thermal history of a basin is closely tied to the lithospheric heat flow and has great impact on the timing and extent of oil and gas generation, phase distribution among reservoir fluids, hydrocarbon migration, diagenetic alteration of minerals, compaction and subsidence of sediments, and development of overpressure.

The lithospheric heat flow vary in time and is closely tied to the geological setting of the basin and the relative vertical distribution between the thickness of upper crust, lower crust, and upper mantle. The location of the boundary between the lower crust and the upper mantle is controlled by isostatic equilibrium or the principle of isostacy. The importance of the relative thickness of the upper crust, lower crust, and upper mantle is related to their different contents of radiogenic heat sources and capacity to insulate through different thermal conductivity.

Numerous simulations studies of the thermal history in a basin show that the heat flow through the lithosphere is close to be steady state and in one dimension upward on a basin scale and transient and three dimensional locally within the basin due to lateral variation in thermal conductivity of the sediments and advective heat flow of migrating fluids.

The results from basin modeling simulations of thermal history in a case study from the North Sea is used to demonstrate the impact of the main driving mechanisms on the lithospheric heat flow including varying paleo-surface temperature tied to plate movements and the cooling effect of rapid subsidence causing the anomaly of an upward decreasing lithospheric heat flow.

 

AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands

 

AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands