PHANEROZOIC FOLD-THRUST BELTS: GLOBAL INVENTORY OF CROSS SECTIONS

Structure cross sections from more than 25 fold-thrust belts (FTB) on four continents are based on data collected during petroleum exploration ventures (1957-2001). Clustered and/or seriated sections are being constructed and/or revised with Macromedia FreeHand-9 on Apple-Macintosh machines. A typical selection has been printed on poster-size paper panels. The selection of graphically intense FTB data shows that the global variation of sizes, bulk strains, geodynamic settings, and resource potential can best be understood with a global inventory of FTB cross sections. Displayed FTB include examples of high-strain, low-strain, thrust- dominated, fold-dominated, and basement upthrust- dominated FTB. Many displayed examples are shown as formed in the Suppe-Dahlstromian domain of low, inhomogeneous, or absent pervasive strain. Seismic documentation, of the commercial and COCORP type, has in the past been vital to establish the present FTB understanding. In the present and future inventory, however, seismic data are few and generally limited to narrow, shallow, external zones. The dip, depth, and curvature of the foreland top are essential parameters of the size, depth extent, and bulk strain of any FTB. In most displayed examples, however, the foreland top is an uncertain extrapolation of flexural-load data documented in the foreland of the FTB.