Brazos River water and mussel shell trace elements and stable isotopes

We performed multi-proxy analyses (δ18O, δ13C, clumped isotopes) from serially-sampled freshwater mussels in two species (Amblema plicata and Cyrtonaias tampicoensis), two specimens each, from the Brazos River, Texas to age specimens and test whether they accurately record environmental conditions such as river discharge and water source. Oxygen isotopic measurements are similar to predicted aragonite δ18O values based on temperature and water δ18O, but the record is complex and irregular. To better resolve the chronologies, we performed clumped isotope analyses on select shell intervals. Clumped isotope temperatures (T(Δ47)) ranged from 19° to 36°C. Summer T(Δ47) values were 3-5°C higher than measured temperatures, suggesting an offset in paleothermometer calibration. Clumped isotope analyses were performed at the former Passey-Levin lab at Johns Hopkins University (now at U. of Michigan) on a Thermo Scientific MAT 253 IRMS with a custon gas purification line. Serial stable isotope samples were MicroMilled and analyzed at the Texas A&M University Stable Isotope Geosciences Facility (Keil carbonate-Thermo Finnigan MAT 253 IRMS). The shells in the samples tab were analyzed in different regions of the shells. The different regions (INL or inner nacreous layer, ONL or outer nacreous layer, umbo or U) yielded data displayed in different tabs in this document. The modern shells are 3R5, 3R3, TP2, and TP3. The historical shells from the UTA NPL collection are H3R and HTP.