Dating of Biogenic and Inorganic Carbonates Using 210Pb-226Ra Disequilibrium Method: A Review

Abstract

The uniqueness of the recent (<100–150 years) carbonate proxies is that the archived paleoclimatological and paleoenvironmental parameters inscribed in them at the time of their formation can be calibrated in most cases with existing hard data and thus, provides an excellent opportunity to verify their utility to retrieve long-term paleorecords. Determination of precise chronology of these proxies such as corals (both shallow and deep-sea), fish bones (otoliths), mollusks, speleothems, and inorganic carbonates that precipitate from natural reservoirs and man-made structures therefore becomes very important. The chronological retrieval of the archived records in these proxies are relevant to several important issues that include development of fisheries management strategies, reconstruction of environmental and geochemical changes that are taking place in coastal, estuarine and lacustrine waters and time frames of the initiation of degradation of engineering structures such as bridges. Several recent developments have contributed to high-precision dating of these carbonates. For example, with the advent of mass spectrometry (both TIMS and ICPMS), it has become possible to make high precision measurements of 226Ra measurements which has significantly reduced uncertainties of 210Pb/226Ra ages. In this article, the current status of the 210Pb/226Ra dating method of biogenic and inorganic carbonates is reviewed and the gaps in this field are discussed.