Stable isotope stratigraphy of a late last interglacial speleothem from Rana, northern Norway

A stalagmite from Rana, northern Norway, dated by the TIMS uranium-series t echnique, yields records of stable oxygen and carbon isotopes covering the period from late marine oxygen isotope substages (MIS) 5e to 5a, that is, 1 23,350 to 73,300 yr ago. Rapid growth (similar to 46 mum/yr) between 123,35 0 and 119,500 yr ago reflects climatic conditions favorable for speleothem growth. This period is characterized by century- to millennial-scale oscill ations in both stable isotope records, where both the absolute values and t he isotope ranges are similar to Holocene and older samples from the region . From 119,500 to 107,700 yr ago, speleothem growth was slow (similar to0.7 mum/yr), and between 107,700 and 73,300 yr ago growth is barely noticeable (0.07 mum/yr). During the period of slow growth the stable isotope records show an overall enrichment trend. The transition between rapid and slow gr owth rate occurring sometime between 119,500 and 107,700 yr ago is believed to reflect the termination of interglacial climate in this region. The abs ence of detritus and corrosion features in the slowly deposited calcite sug gests that the valley outside the cave remained sufficiently ice free for s peleothem growth to occur until at least 73,300 yr ago. (C) 2001 University of Washington.