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Cosmogenic 36 Cl in karst waters: Quantifying contributions from atmospheric and bedrock sources
Author(s) -
Johnston V. E.,
McDermott F.
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2009gl041210
Subject(s) - speleothem , geology , ice core , cave , stalagmite , paleoclimatology , impact crater , atmospheric sciences , climate change , climatology , holocene , astrobiology , paleontology , oceanography , archaeology , history , physics
Improved reconstructions of cosmogenic isotope production through time are crucial to understand past solar variability. As a preliminary step to derive atmospheric 36 Cl/Cl solar proxy time‐series from speleothems, we quantify 36 Cl sources in cave dripwaters. Atmospheric 36 Cl fallout rates are a potential proxy for solar output; however extraneous 36 Cl derived from in‐situ production in cave host‐rocks could complicate the solar signal. Results from numerical modeling and preliminary geochemical data presented here show that the atmospheric 36 Cl source dominates in many, but not all cave dripwaters. At favorable low elevation, mid‐latitude sites, 36 Cl based speleothem solar irradiance reconstructions could extend back to 500 ka, with a possible centennial scale temporal resolution. This would represent a marginal improvement in resolution compared with existing polar ice core records, with the added advantages of a wider geographic range, independent U‐series constrained chronology, and the potential for contemporaneous climate signals within the same speleothem material.