Identification of the last glacial maximum in the Upper Paleolithic of Portugal using magnetic susceptibility measurements of Caldeirão Cave sediments

Abstract

We have sampled Upper and Middle Paleolithic sediments in Caldeirão Cave, Portugal, for paleoclimatic analysis. This work involved measuring magnetic susceptibility (MS) on continuous vertical profiles of a series of ∼8 cc sediment samples, and using the MS data as a paleoclimate proxy. Previous work has shown that caves can be ideal recorders of paleoclimatic variations because they are protected environments. Pedogenesis outside the cave during time of cool climate produces sediments with low MS magnitudes, while warmer climates yield higher MS magnitudes. Eroded soils collect in caves in sediment sequences where futher pedogenesis and biological disturbance is minimal. Continuously sampled profiles of those sediments found in an archaeological context then allow paleoclimatic estimates for all archaeological levels. Results of our work here include identification of the last glacial maximum, at ca. 24,000–22,000 B.P. (calibrated), defined by very low MS values found in basal Solutrean levels in the cave. Distinctive ca. 2500 year Neo‐glacial cycles, defined by the MS data within the Early Upper Paleolithic and Solutrean, are consistent with published 14C duration estimates for the Upper Paleolithic in Caldeirão Cave. © 1998 John Wiley & Sons, Inc.

Magnetic susceptibility applied as an age–depth–climate relative dating technique using sediments from Scladina Cave, a Late Pleistocene cave site in Belgium

“…Furthermore, the authigenic production of maghemite and magnetite produced during pedogenesis appears to be relatively stable chemically [23], resulting in a stable MS signature that is preserved in sediments. The Mö ssbauer spectra and spectral reflectance work suggests the presence of maghemite in the Scladina samples, a result which is consistent with our related work in other European caves [11]. The nanometer size particles, which are superparamagnetic at 295 K, with a magnetization orientation which is fluctuating rapidly on the Mö ssbauer time scale at 295 K and slowly at 4.2 K (Fig.…”

“…Excavation, exposure, observation and dating of sediments deposited in caves makes it possible to recover these stratigraphic sequences while carefully avoiding disturbed or anomalous sediments. Empirical comparisons between sampled sections within individual caves ( [11] and other work) and between caves within a region show a systematically consistent MS result that has been correlated to well dated climatic fluctuations [6]. In addition, we have shown from MS measurement at a number of open air and cave sites, that small-scale diagenetic effects, local disturbances, or other within-site disruptions are not sufficiently extensive to destroy the correlation power of the curves produced.…”

“…Refs. [6][7][8][9][10][11]). When applied to cave sites, MS relative dating applications utilize the independent isotopic and cultural ages available from archaeological levels.…”

Linking speleothem and soil magnetism in the Pau d'Alho cave (central South America)

“…Ideally, the magnetic mineralogy of speleothems can be used to track paleoclimatic oscillations, similar to the magnetic records of soils, loess, and cave clastic sediments [e.g., Maher , ; Ellwood et al ., ]. Almost all rocks contain some iron.…”

The Late Pleistocene clastic deposits in the Romito Cave, southern Italy: a proxy record of environmental changes and human presence

“…ka BP, as evidenced by an increase in plant species (Aksu et al, 1995) and the water-level rise in several lakes (Ramrath et al, 1999;Chondrogianni et al, 2004). A similar climatic trend through the Last Glacial Maximum (LGM) event has also been documented in several caves of Southern Europe using magnetic susceptibility evidence (Ellwood et al, 1998(Ellwood et al, , 2001). 5 ka BP (Harrison and Digerfeldt, 1993;Roberts and Wright, 1993).…”