Paper No. 208-34
Presentation Time: 5:15 PM
A COMPARISON OF TWO COMMON CONTINUOUS FLOW IRMS APPROACHES ON THE ISOPRIME MULTIFLOW AND THE ISOPRIME PYROCUBE FOR δ 13C USING LATE ORDOVICIAN CARBONATES FROM SWEDEN
Nine samples were collected from the Late Ordovician in the Siljan District of Sweden. These samples were collected from rocks (Boda Limestone – Glistjärn Formation) that are known to be from the Hirnantian δ 13C Isotope Excursion (HICE) interval. Carbon isotopic composition will be determined for these samples using two common continuous flow IRMS approaches: 1) head space gas analysis with an IsoPrime MultiFlow automatic injection system and 2) elemental analysis by combustion on an IsoPrime PyroCube. Using the MutiFlow system direct measurement of δ 13C from inorganic carbon can be obtained, however combustion on the PyroCube results in a δ13C value that represents both organic and inorganic carbon in the rock. As a result we will process samples for δ 13C total and for δ 13C org, and then calculate the δ 13C carb (δ 13C total = δ 13C org + δ 13C carb). We will test to see if we get similar values for δ 13C carb using these two methods to determine if it is possible to run samples using only the PyroCube, thus eliminating the need to have two different sample preparations on two different instruments to obtain the same results. The results of the measurements are important, as we will use them to place the samples within Hirnantian Positive Isotope Excursion (HICE). Then, conodonts from these samples will be used to determine the age of the samples and water temperature will be determined using δ18O from the conodont phosphate.