Abstract
In subduction zone the geotherm is thought to vary as a function of subduction rate and the age of the subducting lithosphere. Along a single subduction zone the rate of subduction can strongly vary due to changes in the angle between the trench and the plate convergence vector, namely the subduction obliquity. This phenomenon is observed
all around the Pacific (i.e. Marianna, Sunda-Sumatra, Aleutian. . . ) and is supposed in the geological record of Turkey. However due to observed differences in subducting lithosphere age or lateral convergence rate in nature, the quantification of temperature variation due to obliquity is not obvious and need to be better constrained. In order to investigate this effect, 3D generic numerical models were carried out using the finite element code elefant. We designed a simplified setup to avoid interaction with other parameters. An ocean/ocean subduction setting was chosen and the domain is represented by a 150 x 256 x 150 km deformed Cartesian box. The trench geometry is prescribed by means of a simple sine function. The mantle flow is computed in the mantle wedge by solving the equation of mass and momentum conservation. The energy conservation equation is then applied to this flow solution and solved in the entire domain until steady-state is reached. The results are analysed (i) in terms of mantle wedge flow with emphasis on the trench-parallel component and (ii) in terms of depths-temperature trajectories computed along the plate interface. We show that the effect of the trench curvature on the geotherm with respect to the convergence direction is not negligible. A small obliquity yields to a small but important trench parallel mantle flow that has effects on the advection of heat. In consequences, the isotherm re-adjust to the mantle flow and are deflected with respect to the geometry (different case are presented here: concave, convex or S-shaped). We observe differences of few hundred degrees on the depth-temperature path computed at the interface that is of interest for our understanding of dehydration reaction during subduction related metamorphism and their link to seismicity.
all around the Pacific (i.e. Marianna, Sunda-Sumatra, Aleutian. . . ) and is supposed in the geological record of Turkey. However due to observed differences in subducting lithosphere age or lateral convergence rate in nature, the quantification of temperature variation due to obliquity is not obvious and need to be better constrained. In order to investigate this effect, 3D generic numerical models were carried out using the finite element code elefant. We designed a simplified setup to avoid interaction with other parameters. An ocean/ocean subduction setting was chosen and the domain is represented by a 150 x 256 x 150 km deformed Cartesian box. The trench geometry is prescribed by means of a simple sine function. The mantle flow is computed in the mantle wedge by solving the equation of mass and momentum conservation. The energy conservation equation is then applied to this flow solution and solved in the entire domain until steady-state is reached. The results are analysed (i) in terms of mantle wedge flow with emphasis on the trench-parallel component and (ii) in terms of depths-temperature trajectories computed along the plate interface. We show that the effect of the trench curvature on the geotherm with respect to the convergence direction is not negligible. A small obliquity yields to a small but important trench parallel mantle flow that has effects on the advection of heat. In consequences, the isotherm re-adjust to the mantle flow and are deflected with respect to the geometry (different case are presented here: concave, convex or S-shaped). We observe differences of few hundred degrees on the depth-temperature path computed at the interface that is of interest for our understanding of dehydration reaction during subduction related metamorphism and their link to seismicity.
| Original language | English |
|---|---|
| Publication status | Published - 20 Aug 2017 |
| Event | Nethermod: XV international workshop on modelling of mantle and lithosphere dynamics - Hotel Postillion, Putten, Netherlands Duration: 27 Aug 2017 → 31 Aug 2017 https://nethermod.sites.uu.nl/ |
Conference
| Conference | Nethermod |
|---|---|
| Country/Territory | Netherlands |
| City | Putten |
| Period | 27/08/17 → 31/08/17 |
| Internet address |
