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The Central Basin of the Iran Plateau is between the geologically better-known regions of the Zagros and Alborz Mountains. Hydrocarbon exploration in the Central Basin has revealed the details of the late Eocene-Holocene evolution of the basin based on seismic refl ection data, geological fi eld work, basin modeling, and satellite interpretation. The multistage basin history commenced with broad sag-type subsidence and isolated normal faults during Oligocene-early Miocene time. It evolved to an extensional or transtensional basin in the early-middle Miocene, with as much as 4-5 km of Upper Red Formation section being deposited in some parts of the basin during this stage. The upper part of the Upper Red Formation is associated with a change to transpressional deformation, with the development of thrusts and folds. This latest (probably middle and/or late MioceneHolocene) deformation is transpressional, and includes a mixture of basementinvolved strike-slip and thrust faults and thin-skinned folding and thrusting detached on Oligocene evaporites. Local detachment levels higher in the stratigraphy also exist. Subsidence in mini-foredeep basins and strike-slip fault bounded basins occurred during this stage, and several kilometers of Upper Red Formation were deposited in the main depocenters. Northwest-southeast-to north-northwest-south-southeaststriking dextral strike-slip to compressional faults dominate the area, with subordinate east-west and north-south fault orientations also present. These different fault sets combine in places to form major strike-slip duplex geometries. The Eocene volcanic belt (Urumieh-Dokhtar zone) along the southern margin of the basin forms a chain of massifs as much as 3 km high, the outcrops of which were exhumed by movement along major thrusts from 5-6 km depth between the middle Miocene and present day. The Central Basin-Urumieh-Dokhtar zone forms a

Well exposed, often laminated gypsum sequences occur in many Quarternary salt lakes in southern South Australia. The gypsum in the salt lakes is classified by increasing grain size into gypsite, gypsarenite and selenite. The salt lakes are classified by age and hydrological setting into coastal salinas which are Holocene sea‐water fed groundwater lakes, and continental playas which are late Pleistocene endorheic basins. A study of the relationships between coastal salina hydrology and the associated gypsum deposition has shown the different types of gypsum form under distinct hydrological regimes. As the hydrology above a coastal salina depositional surface changes through time so does the type of gypsum deposited. Application of a gypsum depositional model derived from a study of the coastal salina gypsum to those portions of a continental playa gypsum unit where deposition is no longer occurring confirms the applicability of the model to non‐salina gypsum deposits.