Brown, Alton A.1
(1) Consultant, Richardson, TX
ABSTRACT: Estimating Paleo Heat Flow in Cratonic and Foreland Basins: a Proposed Methodology with Application to the Delaware Basin Area, West Texas and New Mexico
Modern heat flow data provide insights for estimating ancient heat flow where other
approaches are unsatisfactory. First, heat flow increases toward modern
continent-continent collisions (except in adjacent foreland basins). Elevated heat flow is
probably related to lithosphere thinning extending beyond the current collision zone.
Second, average modern heat flow decreases with increasing time since the last crust
heating. Phanerozoic heat flow changes are consistent with lithosphere cooling and
thickening.
The following work flow was used to interpret Delaware basin paleo heat flow. Modeled
tectonic subsidence of the Ordovician to Carboniferous section indicates subsidence
related to Late Cambrian extension. The beta factor was estimated from tectonic subsidence
and used to calculate heat flow during this time. Elevated heat flow caused by Marathon
collision was estimated from distance to collision front using modern calibration. Heat
flow from Early Permian collision until today was estimated using the modern relation
between heat flow and heating age, with adjustment for residual effects of the collision
heating in the current heat flow.
Modern Eastern Delaware basin heat flow is insufficient to account for observed thermal
maturity, even accounting for reasonable Cretaceous deposition and erosion. Heat flow
modeled using the approach suggested here causes modern thermal maturity patterns similar
to those observed in the western Midland basin, Eastern Delaware basin, and Central Basin
Uplift. Heating from Cenozoic volcanics is needed to match anomalously high thermal
maturity in the western Delaware basin.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.