GEOLOGICAL SURVEY A Hewlett-Packard 9830A BASIC language program

Use of trade names is for descriptive purposes only and does not constitute endorsement by the U. S. Geological Survey Three broad geologic environmentB, or reservoirs, having appreciable amounts of U, Th, and Pb and sufficient longevity, are required by the plumbotectonics model. These resevoirs, the mantle, upper continental crust, and lower continental crust, and an additional short-lived mixing orogene provide the necessary chemical environments to produce gross terrestrial isotopic patterns. The transfer of matter among reservoirs is treated as proceeding through cycles called orogenies of discrete, sequential operations that can be expressed by a series of BASIC program statements (paralleling the algebraic equations of the companion paper). From the sets of numerical data generated as matrix arrays, both the total mass distribution and the U, Th, and Pb isotopic contents among reservoirs can be determined as a function of time. Two versions of the model are presented by Zartman and Doe (in press), which follow the same basic program form and differ only in certain parametric values. We list version I in its entirety in Appendix A, and supply the pertinent substitute lines for conversion to version II in Appendix B. In addition to yielding mass distribution and U, Th, and Pb isotopic contents of reservoirs, several output options are available for calculating isotopic ratios, mean age of the crust, and isotope concentrations of reservoirs. A separate subroutine is also provided, which modifies the main program, for computing the mean age of isotopes in the crust. The program was written specifically for use with the Hewlett-Packard model 9830A minicomputer with 8K words of memory, but with a few modifications it could be adapted to several other comparable H-P models. If the appropriate tape cartridge is sent to us at Mailstop 963, Federal enter