The Curie depths of the United Arab Emirates: Implications for regional thermal structures and tectonic terranes

Abstract

We have determined the depth of the Curie isotherm in the United Arab Emirates (UAE) using a modified centroid method based on the fractal distribution of sources. The derived spatial coverage of Curie depths and geothermal gradients are consistent with the geothermal gradients derived from the bottom hole temperatures measured in exploration wells and reveal three NNE–SSW to NE–SW-trending regions of shallow Curie depths. These are: (1) the north-western offshore region of the UAE with Curie depths of 11–25 km; (2) in central UAE ranging from the Shah field in south-central regions of the UAE to the northern offshore region of Dubai, with Curie depths of 10–25 km, high geothermal gradients of 22.1–55.3 °C/km, and high heat flows of 55.3–138.3 mW/m2; and (3) in the eastern region of the UAE from Al Ain to Dibba and the Gulf of Oman, with medium Curie depths of 25–30 km. These regions of shallow Curie depths are flanked by two NS to NE–SW-trending regions of deeper Curie depths between 35 and 50 km with low geothermal gradients and heat flows of 11.1–15.8 °C/km and 27.8–39.5 mW/m2 respectively. We interpreted these regional NE–SW trends to be related to tectonic terranes composed of magmatic arcs and microcontinental fragments that have amalgamated to form the crust beneath the UAE. In addition, many large hydrocarbon fields are located immediately above or on the margins of these shallow Curie depth zones, suggesting that the shallow Curie depth could have played a critical role in the maturation, migration, and entrapment of hydrocarbons in the UAE. Furthermore, since these zones delineate areas of high heat flow (>100 mW/m2) and high geothermal gradients (∼40 °C/km) they represent areas in which future geothermal exploration could be focused.