High heat flow anomalies over salt structures on the Texas Continental Slope, Gulf of Mexico

Abstract

We made 74 closely spaced (< 2 km apart) heat flow measurements around and over two salt structures on the Texas continental slope, Gulf of Mexico. The values outlined the shape of the heat flow anomalies over both structures. Based on a preceding high resolution seismic survey, we interpreted these structures to be a cylindrical plug and a salt tongue extending from the crest of a wall‐shaped feeder. The heat flow observations clearly reflect differences between the two features and are consistent with the prior structural interpretation. The values over the salt plug are nearly all greater than 70 mW/m². The measurements over the salt tongue have a sharp heat flow peak of 90 mW/m² associated with the presumed feeder and rather uniform values around 60 mW/m² over the remainder. The variation of heat flow over both structures is smooth and shows no apparent scatter. Heat flow values off these features are uniformly low, around 30 mW/m². Thermal effects from bottom water temperature fluctuation, slope sedimentation, diapiric movement of the salt body, and pore fluid migration appear unable to provide a satisfactory explanation for the observations. However, thickness variations of a highly conductive salt body can easily account for the heat flow anomalies. We suggest that modeling of the conductive anomaly should provide substantial constraints on the bottom geometry of the salt.

Soil gas 222Rn concentration in northern Germany and its relationship with geological subsurface structures

“…Jensen (1983) described high temperatures above salt domes as a result of enhanced heat flow due to the thermal conductivity of salt and surface layers of low conductivity. This implies a possible upward motion of deeper fluids due to convection (Khutorskoi et al, 2009;Nagihara et al, 1992). Fresh water can enter through the same pathways that account for the partial dissolution of the salt dome margins which give rise to density driven thermohaline convection.…”

“…Salt structures near the surface form geothermal zones (Jensen, 1983;Nagihara et al, 1992) and have an impact on groundwater salinity (Magri et al, 2009). The rise of salt domes provokes faults in the overlying geological strata.…”

Heat flow variations on a slowly accreting ridge: Constraints on the hydrothermal and conductive cooling for the Lucky Strike segment (Mid‐Atlantic Ridge, 37°N)

“…[39] The contrast of conductivity between sediment ($0.8-1 W/m/K) and basalt ($1.5-2.5 W/mK) [Clauser and Huenges, 1995] can potentially contribute to a lateral heat transfer. This heat refraction effect, which has been shown to be important in some specific environments [Nagihara et al, 1992], could generate small wavelength anomalies such as that observed on profile OP or profile CD, where the basement shows a high bounded by two lows. Von Herzen [2004] has discussed some aspect of heat refraction for buried structures in the old ocean crust.…”

Gulf of Mexico, Thermobiogenic Hydrates

“…In another study of the Texas continental slope, Nagihara et al (1992) made 74 measurements within ±10% accuracy of heat flows over 2 irregularly shaped salt domes, spacing samples 1-3 m apart. Nagihara et al found that heat flow ranged from 25 to 40 mW/m 2 beyond salt influence, while ranging from 50 to 100 mW/m 2 directly over the salt.…”