GIS-based documentation of Late Cretaceous-Paleogene magmatism in SE Arizona Brook C.D. Riley GIS in Water Resources CE 394K—Maidment 3 December 2002

Discussion background/study area: data sources: methodology: problem why this time period? why this area? data sources: basemap age data methodology: not rocket science! never been done for this area! products/issues

Problem larger study: exhumation and recycling in synorogenic basins issue: heating/resetting of thermochronometers need to know absolute ages of nearby igneous rocks comparison with cooling ages from low-T thermochronometers integrate heating effects of Late Cretaceous-Paleogene magmatism with thermochronology work on sandstones this project: spatial reference for K-T igneous rock ages/errors all one data set! what do I need? available ages for igneous rocks within study area: literature, published maps location, rock type, mineral, thermochronometer recalculation of K-Ar ages: changes in estimates of decay constants appropriately-scaled basemap: Drewes (1980/2002) Tectonic map of southeast Arizona

Study area

Drewes (1980): Tectonic map of southeast Arizona digital database version 1: 2001; version 2: 2002 latest version has some ages, but…

Santa Rita Mountains — K-Ar ages

Santa Rita Mountains — error comparison

Products/issues queriable spatial reference frame for dated K-T igneous events in SE Arizona: age, error, system, rock type, mineral issues: appropriateness of scale and biases of basemap location/system/material problems: rating the data paucity of data for key areas next up for term project: additional low-T data (from my work) future work: a better basemap? ‘sphere of influence’ polygons

Questions?