Salt Deposition Salt Movement Diapir Structures Imaging Link to faulting
Composition of Salt Domes Salt Deposition Restricted marine basins Mostly halite Minor traces of gypsum or anhydrite Often the two are interbedded and folded
Bonneville Salt Flats, Utah
Gypsum, Ca(SO ).2H 0 4 2 Halite, NaCl
Salt moves driven by buoyancy Sequential Stages of a Salt Diapir
•Salt density= 2 g/ cm3 •Salt undergoes no compaction •Mechanically weak - viscous •Shale Density is initially 40% water •Initial Density = 1.8 g/ cm3 •Water expelled during compaction • Final Density = 2.4 g/ cm3 Salt at the Surface Salt Structures -Iran
Salt Glacier - Iran
Gulf of Gulf of Mexico Mexico Salt
Variety of Salt Structures Internal flow of salt
Jackson et al. 1990 Detection of Salt Domes
Gravity Gravity surveys • Find gravity lows • Low density Seismic Imaging
GM-SYS™ Profile model of salt structure integrating seismic reflection, FTG gravity, and magnetic data (EarthExplorer, 2009).
Seismic Image of a Salt Dome
Geosoft GmsYs-3D model of a salt body embedded in a 3D density volume (Earth Explorer, 2009)_
3D Seismic Interpretation of Salt Sandbox Experiment Relationship between salt dome and normal faulting Structures http://www.beg.utexas.edu/indassoc/agl/animations/AGL95-MM-001/index.html
GUGLIELMO, G., Jr., , B. C. VENDEVILLE, D. D. SCHULTZ-ELA, and M. P. A. JACKSON Bureau of Economic Geology, The University of Texas at Austin, Extension Above Salt Diapir Salt Structures vs. Tectonic Structures
•Caused by movement of salt, not by plate boundary stresses •Often linked to sedimentation •Often localized by tectonic structures •Both upwards movement of salt and salt withdrawal cause deformation
Salt movement affects sediment thickness Salt in the North Sea
Salt Traps Salt is the best seal Examples of Petroleum Salt Provinces • Gulf of Mexico • North Sea • Middle East
Zagros Mts., Iran La Popa Basin, Mexico Ekofisk Field Ekofisk Formation analog W E Late Cretaceous
Shallow Sea Continued regional subsidence Rising sea level Active phytoplankton growth
Van der Bark & Thomas, 1980
Late Cretaceous: Ekofisk Formation Salt Domes Pierce the Strata Time Danish North Sea
CI = 30ms 8km
Crestal Deformation Fractures around Salt Domes
Ant-Tracking displaying radial fracture pattern around salt domes
8km Fossen, 2010 Salt in Compressional Province Salt in Extensional province
Gulf of Mexico
Salt is an excellent detachment surface