Paleoclimate records

Robst AL, Lowenstein TK, Jordan TE, Godfrey LV, Ku T-L, Luo S (2001) A 106 ka paleoclimate record from drill core of the Salar de Atacama, northern Chile. Paleogeo Paleoclim Paleoecol 173 21-42 Rosholt JN (1957) Quantitative radiochemical methods for determination of the sources of natural radioactivity. Anal Chem 29 1398-1408... 

It is essential to understand the isotopic variability within authigenic minerals that form the basis of terrestrial paleoclimate records and between such samples that are isochronous within an outcrop of a stratigraphic formation. Except for variability studies in biogenic materials (teeth, bone, shells) (e.g., Kohn et al. 2002), we know of no paleoaltimetry studies that have examined this natural variability in authigenic or pedogenic proxy materials. Such variability studies should be conducted before any quantitative estimates of paleoelevation can be made. 

PALEOCLIMATE RECORDS FROM SPELEOTHEMS IN LIMESTONE CAVES... 

Bums, S. J., Matter, A., Frank., N, and Mangini, A., 1998, speleothem-based paleoclimate record from northern Oman, Geology. 26 499-502. 

Devils Hole, a steeply dipping (-80°) tectonically fonned planar fissure >165 m deep (Riggs et al., 1994), has been accumulating calcite speleothems that contain at least two different paleoclimate records. Below water table deposits contain a 560,000 year paleo-climate isotopic record (Winograd et al., 1992), while above water table deposits record 120,000 years of changing water table elevation (Szabo et al., 1994). The different depositional environments in Devils Hole control the form of the speleothems. 

The presence of flowstone coatings on the walls of Browns Room raises an interesting possibility for an additional paleoclimate( ) record. The flowstone originates as thin films of carbonate-saturated water flow over the exposed walls, with the most probable source for that carbonate-saturated water being external to Browns Room, that is, from the land surface. Therefore, the flowstone is likely recording periods of local recharge directly into Browns Room. 

Niggeman, S.M., Mangini, A., Richter, D.K. Wurth, G. (2003) A paleoclimate record f the last 17,600 years in stalagmites from the B7 cave, Sauerland, Germany. Quaternary Science Reviews 22, 555-567. 

Smith, G.I. Bischoff, J.L. (1997) An 800,000-year paleoclimate record from core OL-92, Owens Lake, southeast California. Geological Society of America, Special Paper 317. 

Another important aspect of ground-water paleoclimate records is the possibility to relate the absolute temperature estimates obtained from the noble gases to the relative temperature indicator provided by the stable isotope composition of the water (5 0 and 5 H). In most noble gas paleotemperature studies, stable isotopes ratios have also been determined, and in many cases clear relationships between the two climate proxys were found (e.g., Heaton et al. 1986 Stute and Deak 1989 Beyerle et al. 1998 Huneau et al. 2001). Such relationships offer the chance to derive local slopes for the long-term S O/T-relationship. 

Typically, coral-derived paleoclimate records are studied on three timescales seasonal, interannual-to-decadal, and long-term trends. The seasonal variation refers to one warm and one cool phase each year. An abrupt shift in the proxy s long-term mean often indicates a decadal modulation in the data. Long-term trends are usually associated with a gradual increase or decrease in the measured proxy over the course of several decades or centuries. The following sections explore some of the seasonal, decadal and long-term trends in coral-derived paleoclimate records and some of the limitations associated with interpreting coral proxy records. 

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