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Caves occur everywhere on our planet, from the tropics to the high latitudes and from below sea level to alpine settings. Cave morphologies provide clues to their formation mechanisms, and their iconic mineralogical features—stalagmites and stalactites—carry a wealth of paleoenvironmental information encoded in their geochemistry and mineralogy. Recent work demonstrates a striking improvement in our ability to decode these paleoenvironmental proxies, and dramatic geochronological advances enable higher resolution records that extend further back in geologic time. Cave research addresses an ever-increasing range of geoscience problems, from establishing the timing and mechanisms of climate change to uncovering detailed records of geomagnetic field behavior.
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USING HIGH-RESOLUTION X-RAY COMPUTED TOMOGRAPHY TO TEST THE SUITABILITY AND GUIDE THE PREPARATION OF STALAGMITES FOR PALEOCLIMATE RECONSTRUCTION
Stalagmites being prepared for paleoclimate analysis should typically be slabbed along the central growth axis. This is an important first step because it allows for the highest resolution of sampling with minimal over- or under-sampling of the growth layers. Further, stable isotope ratios and trace element concentrations along the central growth axis most closely record climate variability. Choosing how to slab to best expose the central growth axis for geochemical sampling is challenging based on external morphology alone. High-resolution X-ray computed tomography (XRCT) can provide the ability to discern the internal growth morphology of stalagmites non-destructively, inexpensively, and rapidly. These data can inform selection of optimal slabbing plane(s) and can help identify locations for preliminary U-series dating. We develop a conceptual screening model to assess rapidly the internal morphologies of uncut stalagmites. The specifics of screening the internal morphologies through XRCT scans include investigating the internal porosity of the sample, the number and size of voids and hiatuses, and the presence and absence of growth layers and growth axes. We demonstrate that XRCT scans capture the migration of center of growth in uncut stalagmites of both simple and complex internal morphologies. XRCT scanning facilitates the investigation of stalagmites with complex internal growth banding, opening up avenues to work on such samples when stalagmites with simpler internal morphologies are not available. Further, screening stalagmites for paleoclimate reconstructions using XRCT improves the sustainability of speleothem science by helping researchers select which stalagmites should be returned to caves without destructive slabbing, thereby minimizing impact on caves.
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- Award ID(s):
- 2203052
- PAR ID:
- 10420104
- Date Published:
- Journal Name:
- Journal of caves and karst studies
- Volume:
- 85
- Issue:
- 1
- ISSN:
- 1090-6924
- Page Range / eLocation ID:
- 1-15
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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