New Mexico Geological Society Annual Spring Meeting — Abstracts

The New Mexico Bureau of Mines and Mineral Resources is in the process of compiling Phanerozoic isotopic ages for New Mexico. The data, entered into an ACCESS database comprises 2100 published and unpublished radiometric ages of Phanerozoic rocks in New Mexico.

Nine isotopic methods have been used to determine the above radiometric ages: Potassium/Argon, Argon⁴⁰/₃₉, Rubidium/Strontium, Uranium/Lead, Uranium/Thorium-disequilibrium, Chlorine³⁶/₃₅, Helium³, Carbon¹⁴, and Fission Track. An age is entered into a Main table where the sample is assigned a unique number. In the Main table there are thirty fields common to every data point including: method, age, material dated, rock, formation, region, location (more specific than region), latitude and longitude, quad, county, and 2 references.

The unique sample number links the Main table to specific isotopic system tables where analytical data can be reported. There are nine separate analytical tables, one for each of the above mentioned isotopic systems.

In the Main table a maximum of two references can be reported. The first reference is the reference where the age was first reported. The second reference often gives more detailed analytical data or sample location. The two reference fields are followed by abbreviations which link to the Bibliographic table where one can search for the authors names in full, the title and journal where the article was published. 330 references have been cited as of 2/9/96

The search capabilities of ACCESS allow searches to be made on any field or combination of fields.

The first step in data entry is to produce a hard copy, individual forms have been designed for each isotopic system. The data is then entered into database. One of the main problems encountered in compiling this database was the lack of geographic location for many data points. Of the 2100 ages only 60% reported latitude and longitude locations, 10% had locations reported by Section, Township, Range. For the remammg 30% Lat./Long was determined from published maps and location descriptions and are therefore not as accurate as the reported Lat./Long data.

We hope to have this database accessible to the public by the end ofthe year. To aid maintaining this database we would request that authors publish Lat./Long data or make it available to us. At the present time we are working on expanding the analytical data that can be presented. The newer isotopic systems require that more analytical data be reported if the dates are to be evaluated. Formats for reporting Ar/Ar, Cl³⁶/₃₅, and He³ are being developed so that authors can send analytical data to us on disc or via email.

A separate but linked database is being developed for ages determined by other methods such as ESR (Electron Spin Resonance) dating.