1. 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

2. 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

3. 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

4. Study area

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

6. Santa Rita Mountains — K-Ar ages

7. Santa Rita Mountains — error comparison

8. 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

9. Questions?