The "topographic recharge" and "tectonic compaction" models for subsurface
fluid flow may have been overapplied to the question of the origin of regio
nal hydrothermal dolomite bodies. These have been attractive models to expl
ain hydrothermal dolomitization because of their obvious applicabilty to th
e present day hydrology of continental interiors. However, recent modelling
studies indicate that topographic recharge does not predict the uniform re
gional trends of dolomite precipitational temperatures observed in hydrothe
rmal dolomites, and that tectonic compaction requires an unreasonable degre
e of fluid focusing to achieve precipitational temperatures equal to observ
ed dolomite fluid inclusion homogenization temperatures. Topographic rechar
ge also has the limitation of flushing solutes out of the system, rendering
it incapable of further dolomitization. In addition, both topographic rech
arge and tectonic compaction are unlikely flow mechanisms to explain the or
igin of extensive open space dolomite cement because of their limited suppl
y of solute.
Thermal convection, on the other hand, can support long-lived flow systems
that are capable of recycling subsurface solutions many times through the r
ock mass. This enhances the opportunity for open space dolomite cementation
. Because thermal convection can occur in confined aquifers beneath the sea
bed, seawater-derived solutions may be continually added to the convection
system. Added seawater would enhance the dolomitization potential of the c
onvection system. The documentation of crustal scale convection systems wit
hin subaerially exposed orogenic belts and the outcrop evidence of both upw
ard and downward extending bodies of hydrothermal dolomite adds credence to
the hypothesis that thermally driven convective flow occurred within ancie
nt platform carbonates, and may have induced regional hydrothermal dolomiti
zation.