Fluid flow at the toe of convergent margins: interpretation of sharp pore-water geochemical gradients

Details Fluid flow at the toe of convergent margins: interpretation of sharp pore-water geochemical gradients Fluid flow at the toe of convergent margins: interpretation of sharp pore-water geochemical gradients

Aug 2003

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003e%26psl.213..261s&link_type=abstract

Earth and Planetary Science Letters, Volume 213, Issue 3-4, p. 261-270.

Computer Science

11

Scientific paper

Fluid expulsion greatly impacts chemical and mass budgets at subduction zones, particularly if it is focused along faults and stratigraphic conduits. Geochemical anomalies centered at décollement zones, such as pore-water freshening and the presence of thermogenic hydrocarbons, indicate long-distance, focused flow of deeply sourced fluids. The sharp gradient of these anomalies below the décollement zone has been interpreted as evidence for recent pulses of fluid flow, initiating a few to tens of ka. However, this interpretation does not consider that underthrust sediments are moving arcward beneath the décollement zone. In addition, upward flow from the compacting underthrust sediments can modify chemical profiles. Here, we use a simple model that couples fluid flow and solute transport to evaluate these sharp chemical gradients. We find that observed geochemical anomalies at the Northern Barbados and Costa Rican subduction zones can be explained either by recent pulses of flow, or by sustained flow along the décollement zone coupled with modest vertical fluid expulsion from consolidating underthrust sediments. The latter interpretation is consistent with estimates of upward flow rate at Costa Rica based on estimated pore pressure gradients and measured permeabilities within the underthrust sediments. One important implication is that recent pulses of flow along fault conduits may not be required to explain the geochemical anomalies. Furthermore, mixing of locally derived fluids flowing upward from the underthrust sediments and deeply sourced fluids flowing along the décollement zone provides an explanation for the observed changes in pore-water freshening along the décollement at Costa Rica.

Affiliated with

Also associated with

No associations

Rating

Fluid flow at the toe of convergent margins: interpretation of sharp pore-water geochemical gradients does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Fluid flow at the toe of convergent margins: interpretation of sharp pore-water geochemical gradients, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fluid flow at the toe of convergent margins: interpretation of sharp pore-water geochemical gradients will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1668189