NOTES ON GROWTH FAULTS AND SEDIMENTARY BED MOTIONS

The behavior of sediments in response to faults, and the corresponding influence of the sediments on the faults, are problems that control o r modify substantially the evolution of sedimentary structures, fluid migration pathways, and the later deposition of post-fault sedimentary units. The self-consistent evolution of faults and sedimentary beds, including both footwall and hanging-wall motion of the beds, is invest igated here using a novel inverse procedure which is guaranteed to hon or present-day data on fault and bed positions. Paleo-evolution of bot h the faults and sediments is handled through constraint criteria such as conserved sediment area, bed-length, desired depositonal and/or bo undary conditions, or prescribed throw of sediments along a fault curv e with time, etc. A procedure is given for using the constraint criter ia either individually or collectively, with or without relative weigh ting conditions. In addition, for the cases of observed multiple fault s, which either overlap laterally in a section or which are separated with no lateral overlap, a mapping procedure is given for transforming all such faults to a much simpler coordinate frame in which all the f aults are (a) vertical, (b) of constant length, (c) do not overlap. Th e mapping procedure is shown to be universally valid for all times, so that the faults stay fixed and the sedimentary beds move through the new coordinate frame with time. Growth and arcuate faults are accommod ated by the mapping procedure, as are flower and inverted flower arran gements of faults. The constraint criteria controlling paleo-evolution are also shown to be mappable to the new coordinate frame, so that de sired paleo-evolutionary constraints can be easily accommodated throug h time-dependence of the mapping functions. The general mapping proced ure, and the inverse method given for obtaining those parameters which describe paleo-evolution of faults and sediments in a self-consistent manner, are of use in addressing a wide variety of evolving fault/sed iment interactions with a guarantee that the control criteria imposed will automatically honor present-day observations of both the faults a nd the sedimentary beds.