Volcanic aerosol records and tephrochronology of the Summit, Greenland, ice cores

• Main Authors: Zielinski, Gregory A., Mayewski, Paul A., Meeker, L. David, Gronvold, Karl, Germani, Mark S., Whitlow, Sallie I., Twickler, Mark S., Taylor, Kendrick C.
• Format: Text
• Language: unknown
• Published: University of New Hampshire Scholars' Repository 1997
• Subjects: Greenland; Saksunarvatn; Vatnaöldur; Greenland ice core; Greenland Ice core Project; Greenland ice cores; Greenland Ice Sheet Project; ice core; Ice Sheet; Iceland; North Atlantic
• Online Access: https://scholars.unh.edu/faculty_pubs/351; https://scholars.unh.edu/cgi/viewcontent.cgi?article=1350&context=faculty_pubs

The recently collected Greenland Ice Sheet Project 2 (GISP2) and Greenland Ice Core Project ice cores from Summit, Greenland, provide lengthy and highly resolved records of the deposition of both the aerosol (H2SO4) and silicate (tephra) components of past volcanism. Both types of data are very beneficial in developing the hemispheric to global chronology of explosive volcanism and evaluating the entire volcanism‐climate system. The continuous time series of volcanic SO42− for the last 110,000 years show a strong relationship between periods of increased volcanism and periods of climatic change. The greatest number of volcanic SO42− signals, many of very high magnitude, occur during and after the final stages of deglaciation (6000–17,000 years ago), possibly reflecting the increased crustal stresses that occur with changing volumes of continental ice sheets and with the subsequent changes in the volume of water in ocean basins (sea level change). The increase in the number of volcanic SO42− signals at 27,000–36,000 and 79,000–85,000 years ago may be related to initial ice sheet growth prior to the glacial maximum and prior to the beginning of the last period of glaciation, respectively. A comparison of the electrical conductivity of the GISP2 core with that of the volcanic SO42− record for the Holocene indicates that only about half of the larger volcanic signals are coincident in the two records. Other volcanic acids besides H2SO4 and other SO42− sources can complicate the comparisons, although the threshold level picked to make such comparisons is especially critical. Tephra has been found in both cores with a composition similar to that originating from the Vatnaöldur eruption that produced the Settlement Layer in Iceland (mid‐A.D. 870s), from the Icelandic eruption that produced the Saksunarvatn ash (∼10,300 years ago), and from the Icelandic eruption(s) that produced the Z2 ash zone in North Atlantic marine cores (∼52,700 years ago). The presence of these layers provides absolute time lines for correlation ...