 |
| Titel |
Using salinity and temperature data to constrain numerical models of deep topography-driven flow in sedimentary basins |
| VerfasserIn |
E. Luijendijk, M. A. Person, M. Ter Voorde, R. T. Van Balen, P. A. M. Andriessen |
| Konferenz |
EGU General Assembly 2012
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250060038
|
|
|
|
|
|
| Zusammenfassung |
| Heat flow and thermochronological studies frequently document thermal effects that are
ascribed to deep groundwater flow. However, the high uncertainty and heterogeneity of
subsurface permeability have hampered model studies of the thermal effect of groundwater
flow. We incorporate groundwater salinity data and new permeability upscaling algorithms to
constrain basin-scale groundwater flow in the Roer Valley Graben in the southern
Netherlands. Subsurface temperature data from the Roer Valley Graben show up to 20
°C variation in temperature in the upper 1000 m of the basin’s sediments, which
do not coincide with any trends in thermal conductivity or crustal thinning and
may therefore be related to groundwater flow. In addition, groundwater salinity
data from the basin show that the fresh-salt water boundary is located up to 1000
m below the base of Pliocene-Quaternary continental deposits, which suggests
freshening of the underlying marine sediments by meteoric water. We explore the extent
topography driven flow using the numerical model code Rift2D. Effective model-scale
permeability was calculated from the variability of clay content observed in borehole logs,
using a new efficient upscaling algorithm. The average temperature change resulting
from topography-driven flow in four model scenarios that captured the uncertainty
of permeability ranged from -3 to -17 °C. Salinity data provide strong additional
constraints on basin-scale flow. The model scenario that matches both the available
salinity and temperature data results in an average cooling of 14 °C with maximum
values of 40 °C. As the topographic gradients in the Roer Valley Graben do not
exceed 1 %, these results imply that topography driven flow can significantly alter
subsurface temperatures even in settings where only a limited relief is present. |
|
|
|
|
|
|