| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Schreurs, G., et al.
(författare)
-
Analogue benchmarks of shortening and extension experiments
- 2006. - 253
-
Ingår i: <em> </em>Analogue and Numerical Modeling of Crustal-Scale Processes. - : Geological Society of London. - 1862391912 ; , s. 1-27
-
Bokkapitel (refereegranskat)abstract
- We report a direct comparison of scaled analogue experiments to test thereproducibility of model results among ten different experimental modelling laboratories.We present results for two experiments: a brittle thrust wedge experiment and a brittleviscousextension experiment. The experimental set-up, the model construction technique,the viscous material and the base and wall properties were prescribed. However, each laboratoryused its own frictional analogue material and experimental apparatus. Comparisonof results for the shortening experiment highlights large differences in model evolutionthat may have resulted from (1) differences in boundary conditions (indenter or basal-pullmodels), (2) differences in model widths, (3) location of observation (for example, sidewallversus centre of model), (4) material properties, (5) base and sidewall frictional properties,and (6) differences in set-up technique of individual experimenters. Six laboratories carriedout the shortening experiment with a mobile wall. The overall evolution of their models isbroadly similar, with the development of a thrust wedge characterized by forward thrustpropagation and by back thrusting. However, significant variations are observed inspacing between thrusts, their dip angles, number of forward thrusts and back thrusts, andsurface slopes. The structural evolution of the brittle-viscous extension experiments issimilar to a high degree. Faulting initiates in the brittle layers above the viscous layer in close vicinity to the basal velocity discontinuity. Measurements of fault dip angles and faultspacing vary among laboratories. Comparison of experimental results indicates an encouragingoverall agreement in model evolution, but also highlights important variations in thegeometry and evolution of the resulting structures that may be induced by differences inmodelling materials, model dimensions, experimental set-ups and observation location
|
|
| 5. |
- Schreurs, Guido, et al.
(författare)
-
Benchmarking analogue models of brittle thrust wedges
- 2016
-
Ingår i: Journal of Structural Geology. - : Elsevier BV. - 0191-8141 .- 1873-1201. ; 92, s. 116-139
-
Tidskriftsartikel (refereegranskat)abstract
- We performed a quantitative comparison of brittle thrust wedge experiments to evaluate the variability among analogue models and to appraise the reproducibility and limits of model interpretation. Fifteen analogue modeling laboratories participated in this benchmark initiative. Each laboratory received a shipment of the same type of quartz and corundum sand and all laboratories adhered to a stringent model building protocol and used the same type of foil to cover base and sidewalls of the sandbox. Sieve structure, sifting height, filling rate, and details on off-scraping of excess sand followed prescribed procedures. Our analogue benchmark shows that even for simple plane-strain experiments with prescribed stringent model construction techniques, quantitative model results show variability, most notably for surface slope, thrust spacing and number of forward and backthrusts. One of the sources of the variability in model results is related to slight variations in how sand is deposited in the sandbox. Small changes in sifting height, sifting rate, and scraping will result in slightly heterogeneous material bulk densities, which will affect the mechanical properties of the sand, and will result in lateral and vertical differences in peak and boundary friction angles, as well as cohesion values once the model is constructed. Initial variations in basal friction are inferred to play the most important role in causing model variability. Our comparison shows that the human factor plays a decisive role, and even when one modeler repeats the same experiment, quantitative model results still show variability. Our observations highlight the limits of up-scaling quantitative analogue model results to nature or for making comparisons with numerical models. The frictional behavior of sand is highly sensitive to small variations in material state or experimental set-up, and hence, it will remain difficult to scale quantitative results such as number of thrusts, thrust spacing, and pop-up width from model to nature.
|
|
