https://cir.cenieh.es/bitstream/20.500.12136/549/1/StalAge%20%e2%80%93%20An%20algorithm%20designed%20for%20construction%20of%20speleothem%20age%20models_Scholz_et_Hoffmann_2011.pdf

StalAge – An algorithm designed for construction of speleothem age models

Carbon and oxygen isotopes in calcite speleothems are powerful proxies for understanding past climate change. For calcite deposited under isotopic equilibrium conditions, variations in d 18 O values directly reflect changes in cave temperature and the isotopic composition of meteoric water. Speleothem d 13 C values have bedrock, atmospheric, and soil gas sources. Soil gases can be traced to the overlying vegetation, which is related to climate. Both d 13 C and d 18 O values are therefore potentially powerful tracers of climate change. Processes that could alter speleothem d 13 C and/or d 18 O values, and thereby mask primary environmental signals, fall in the categories of 1) kinetic processes, including deposition of calcite out of isotopic equilibrium, and 2) vadose processes, including evaporation of water at or near the land surface. In truth, there is no absolute test for the absence of these kinetic/vadose-zone processes. However, the Hendy Test is widely used for assessing whether isotopic equilibrium existed during the time of calcite deposition. Criterion (1) of the Hendy Test (i.e., that d 18 O values remain constant along a single growth layer) may not be a valid control of equilibrium conditions because isotopic equilibrium could theoretically occur in the center of the speleothem at the same time that kinetic fractionation occurs at the flanks. Moreover, the concept of sampling along a single growth layer is flawed in both theory and practice. Criterion (2) of the Hendy Test (i.e., that there is no relationship between d 13 C and d 18 O) is based on the assumption that speleothem d 13 C values are not linked to climate. However, speleothem d 13 C values may well be linked to climate because climate provides a first-order control on soil productivity and the type of vegetation. Therefore, Hendy Test criterion (2) is not a prerequisite to isotopic equilibrium in all cases. We propose instead the Replication Test (i.e., the demonstration of similar isotopic profiles among two or more speleothems) for evaluating the likelihood of calcite deposition under isotopic equilibrium conditions. Replication of isotopic profiles among two or more speleothems is possible only if kinetic/vadose-zone processes are either: 1) absent or 2) have affected spatially separated speleothems in exactly the same way. Because the second scenario is highly unlikely, we propose that the Replication Test is effectively sufficient in ruling out kinetic/vadose- zone overprinting processes. We further suggest that the Replication Test is far more robust in testing for the absence of the wide range of processes described above than is the traditional Hendy Test.

/pdf/limitations-of-hendy-test-criteria-in-judging-the-35fl0riktr.pdf

Limitations of hendy test criteria in judging the paleoclimatic suitability of speleothems and the need for replication

100,000 Years of African monsoon variability recorded in sediments of the Nile margin

High-temporal resolution pollen record from the Alboran Sea ODP Site 976, pollen-based quantitative climate reconstruction and biomisation show that changes of Mediterranean vegetation have been clearly modulated by short and long term variability during the last 25 000 years. The reliability of the quantitative climate reconstruction from marine pollen spectra has been tested using 22 marine core-top samples from the Mediterranean. The ODP Site 976 pollen record and climatic reconstruction confirm that Mediterranean environments have a rapid response to the climatic fluctuations during the last Termination. The western Mediterranean vegetation response appears nearly synchronous with North Atlantic variability during the last deglaciation as well as during the Holocene. High-resolution analyses of the ODP Site 976 pollen record show a cooling trend during the Bolling/Allerod period. In addition, this period is marked by two warm episodes bracketing a cooling event that represent the Bolling-Older Dryas-Allerod succession. During the Holocene, recurrent declines of the forest cover over the Alboran Sea borderlands indicate climate events that correlate well with several events of increased Mediterranean dryness observed on the continent and with Mediterranean Sea cooling episodes detected by alkenone-based sea surface temperature reconstructions. These events clearly reflect the response of the Mediterranean vegetation to the North Atlantic Holocene cold events.

/pdf/rapid-climatic-variability-in-the-west-mediterranean-during-64at5rqyz8.pdf

Rapid climatic variability in the west Mediterranean during the last 25 000 years from high resolution pollen data

http://gsbm.fr/publications/perou/2008_EPSL_275_vanBreukelen.pdf

Fossil dripwater in stalagmites reveals Holocene temperature and rainfall variation in Amazonia

Timing and dynamics of the last deglaciation from European and North African δ13C stalagmite profiles—comparison with Chinese and South Hemisphere stalagmites

V. Plagnes

Papers

Timing and dynamics of the last deglaciation from European and North African δ13C stalagmite profiles—comparison with Chinese and South Hemisphere stalagmites