TRADITIONAL AND EMERGING GEOCHEMICAL PROXIES IN FORAMINIFERA

AbstractThe drivers of organic carbon (OC) burial efficiency are still poorly understood despite their key role in reliable projections of future climate trends. Here, we provide insights on this issue by presenting a paleoclimate time series of sediments, including the OC contents, from Lake Veliko jezero, Croatia. The Sr/Ca ratios of the bulk sediment are mainly derived from the strontium (Sr) and calcium (Ca) concentrations of needle-like aragonite in Core M1-A and used as paleotemperature and paleohydrology indicators. Four major and six minor cold and dry events were detected in the interval from 8.3 to 2.6 calibrated kilo anno before present (cal ka BP). The combined assessment of Sr/Ca ratios, OC content, carbon/nitrogen (C/N) ratios, stable carbon isotope (δ13C) ratios, and modeled geochemical proxies for paleoredox conditions and aeolian input revealed that cold and dry climate states promoted anoxic conditions in the lake, thereby enhancing organic matter preservation and increasing the OC burial efficiency. Our study shows that the projected future increase in temperature might play an important role in the OC burial efficiency of meromictic lakes.

Download Full-text

Geochemical proxies for water-soil interactions in the hyperarid Atacama Desert, Chile

CATENA ◽

10.1016/j.catena.2021.105531 ◽

2021 ◽

Vol 206 ◽

pp. 105531

Author(s):

Felix L. Arens ◽

Alessandro Airo ◽

Jenny Feige ◽

Christof Sager ◽

Uwe Wiechert ◽

...

Keyword(s):

Atacama Desert ◽

Geochemical Proxies

Download Full-text

Precise Temporal Correlation of Holocene Mollusk Shells Using Sclerochronology

Quaternary Research ◽

10.1006/qres.1999.2107 ◽

2000 ◽

Vol 53 (2) ◽

pp. 236-246 ◽

Cited By ~ 105

Author(s):

Thomas M. Marchitto ◽

Glenn A. Jones ◽

Glenn A. Goodfriend ◽

Christopher R. Weidman

Keyword(s):

Shell Growth ◽

Morphological Characteristics ◽

Temporal Correlation ◽

Band Width ◽

Georges Bank ◽

Arctica Islandica ◽

Mollusk Shells ◽

Aspartic Acid Racemization ◽

Geochemical Proxies ◽

Growth Bands

AbstractAnnual growth bands of mollusk shells record several types of paleoenvironmental information, including geochemical proxies for water properties and morphological characteristics of growth and mortality. Sclerochronology, the marine counterpart of dendrochronology, offers a way to link individual shells together to form long continuous records of such parameters. It also allows for precise dating of recent shells and identification of contemporaneous fossil individuals. The longevity of the ocean quahog Arctica islandica (commonly >100 yr) makes this species well suited for sclerochronology. Band width records of contemporaneous A. islandica specimens from the same region exhibit high correlations (ρ = 0.60–0.80 for spans of ≥30 bands), indicating some common environmental influences on shell growth. By adopting several strict criteria, fossil (dead-collected) shells can be linked into composite sclerochronologies. A seven-shell 154-yr chronology was constructed for Georges Bank using three live-collected and four dead-collected shells. Band width matching indicates that the dead-collected individuals died in A.D. 1950, 1971, 1978, and 1989. Sclerochronological age assignments were verified using aspartic acid racemization dating. Construction of a 1000-yr sclerochronology is judged to be feasible using the described methods.

Download Full-text