Fig. 6. High-resolution (c. 1-2 cm spacing) stable isotope records of bulk carbonate across the LPTM at ODP Site 1051 (Blake Nose, western North Atlantic) and ODP Site 690 (Southern Ocean) after Bains et al. (1999). Noteworthy features are the close correlation that can be achieved during the LPTM despite the considerable difference in location of the two sites, and the set of 'steps' leaving to the most negative ¹³C during the onset the LPTM. These 'steps' suggest that ¹²C introduced into the biosphere in a series of rapid pulses separated by intervals of approximate balance between outgassing and carbon burial. Bains et al. (1999) proposed that the 'steps' reflect massive failure of methane hydrate reservoirs.