Summary of 40Ar/39Ar results from sediment core CRP-2A (Table 1) ...

• Main Author: McIntosh, W C
• Format: Dataset
• Language: English
• Published: PANGAEA 2004
• Subjects: DEPTH, sediment/rock; Sample ID; Sample comment; Comment; Age, dated material; Sample method; Number; Argon-39; Calcium/Potassium ratio; Age, dated; Age, error; Core wireline system; Isotope ratio mass spectrometry; see comment; CRP-2; Sampling/drilling from ice; Cape Roberts Project CRP; Antarc*; Antarctica; antartic*; Victoria Land
• Online Access: https://dx.doi.org/10.1594/pangaea.194709; https://doi.pangaea.de/10.1594/PANGAEA.194709

40Ar/39Ar analyses of tephra and clasts of volcanic rock provide age constraints for upper parts of the CRP-2A core. Single-crystal laser-fusion analyses of anorthoclase phenocrysts from three tephra-bearing layers yielded the most precise age constraints for CRP-2A. The dated tephra layers are: 1) a 2.7-m-thick interval of pumice and ash layers between 111.5 and 114.2 meters below sea floor (mbsf) (weighted mean age = 21.44 ± 0.05 Ma, +2.2); 2) a concentration of pumice near 193.4 mbsf (23.98 ± 0.13 Ma): and 3) a concentration of pumice near 280 mbsf (24,22 ± 0.03 Ma) (all ages are calibrated relative to Fish Canyon Tuff sanidine at 27.84 Ma). The 111 to 114 mbsf tephra is almost entirely non-reworked, and the 193 mbsf and 280 mbsf tephra concentrations are interpreted as being reworked and redeposited soon after eruption. All three of the tephra ages are therefore considered to be equivalent to depositional ages. The variation in precision of these three age determinations is largely a function of ... : Supplement to: McIntosh, W C (2000): 40Ar/39Ar geochronology of tephra and volcanic clasts in CRP-2A, Victoria Land Basin, Antarctica. Terra Antartica, 7(4), 621-630 ...