Hydrothermal circulation and intraplate deformation: constraints and predictions from in-situ measurements and mathematical models

Abstract

During ODP Leg 116, three sites were drilled on a transect across two tilted fault blocks in the region of central Indian Ocean intraplate deformation. Well logs and core analyses from these sites, when combined with site survey data, provide detailed information about the physical, chemical, hydraulic, and thermal properties of the 2 km thick sedimentary sequence. Within the underformed sediments, heat flow matches the 52 mW/m2 predicted by cooling plate models for 78 Ma crust. Within 5 km of a buried reversed fault, heat flow averages 84 mW/m2 and reaches values as high as 166 mW/m2. Evidence from downhole temperatures, interstitial water chemistry, and sediment diagenesis establishes the presence of active hydrothermal circulation near the buried fault. A mathematical model has been developed to study the nature and magnitude of this hydrothermal flow. -from Author