Abstract
Carbonate minerals are common in both marine and lacustrine records, and are frequently used for paleoenvironmental reconstructions. The sedimentary sequence of the endorheic Dead Sea and its precursors contain aragonite laminae that provide a detailed sedimentary archive of climatic, hydrologic, limnologic and environmental conditions since the Pleistocene. However, the interpretation of these archives requires a detailed understanding of the constraints and mechanisms affecting CaCO3 precipitation, which are still debated. The implications of aragonite precipitation in the Dead Sea and in its late Pleistocene predecessor (Lake Lisan) were investigated in this study by mixing natural and synthetic brines with a synthetic bicarbonate solution that mimics flash-floods composition, with and without the addition of extracellular polymeric substances (EPS). Aragonite precipitation was monitored, and precipitation rates and carbonate yields were calculated and are discussed with respect to modern aquatic environments. The experimental insights on aragonite precipitation are then integrated with microfacies analyses in order to reconstruct and constrain prevailing limnogeological processes and their hydroclimatic drivers under low (interglacial) and high (glacial) lake level stands. Aragonite precipitation took place within days to several weeks after the mixing of the brines with a synthetic bicarbonate solution. Incubation time was proportional to bicarbonate concentration, and precipitation rates were partially influenced by ionic strength. Additionally, extracellular polymeric substances inhibited aragonite precipitation for several months. As for the lake's water budget, our calculations suggest that the precipitation of a typical aragonite lamina (0.5 mm thick) during high lake stand requires unreasonable freshwater inflow from either surface or subsurface sources. This discrepancy can be resolved by considering one or a combination of the following scenarios; (1) discontinuous aragonite deposition over parts of the lake floor; (2) supply of additional carbonate flux (or fluxes) to the lake from aeolian dust and the remobilization and dissolution of dust deposits at the watershed; (3) carbonate production via oxidation of organic carbon by sulfate-reducing bacteria. Altogether, it is suggested that aragonite laminae thickness cannot be directly interpreted for quantitatively reconstructing the hydrological balance for the entire lake, they may still prove valuable for identifying inherent hydroclimatic periodicities at a single site.
| Original language | American English |
|---|---|
| Article number | 120261 |
| Journal | Chemical Geology |
| Volume | 576 |
| DOIs | |
| State | Published - 20 Aug 2021 |
Bibliographical note
Funding Information:This study was funded by the PALEX project “ Paleohydrology and Extreme Floods from the Dead Sea ICDP core ” of the DFG (grant no. BR2208/13-1/-2 ), and by the Center of Excellence of The Israel Science Foundation (grant No. 1436/14). Tomer Flax and Itamar Levitan had participated in the research as part of the Alpha program for gifted high school students and had contributed equally to this manuscript. The assistance of Adi Ticher, Ofir Tirosh, Prof. Nir Keren, Adam Levi, and Prof. Jonathan Erez are extremely appreciated. The members of the Dead Sea Observatory team of the Geological Survey of Israel ( https://gsideadsea.wixsite.com/dso-gsi ) are thanked for providing the Dead Sea brine. We are also grateful to Dr. Gadi Weiss and Prof. Aharon Kaplan for providing the EPS. Exchange of ideas, fruitful discussions, and assistance from Moshe (Koko) Armon, Ziv Mor, Drs. Nadav Lensky, Ido Sirota and Michael Beyth, and Profs. Aharon Oren, Boaz Lazar, Jonathan Erez are appreciated as well. We are also grateful for a detailed and useful colleague review by Prof. Abraham Starinsky and by two anonymous reviewers that substantially improved the manuscript. Yoav Ben Dor is grateful for scholarships from the Hebrew University Advanced School of Environmental Studies and the Rieger Foundation-Jewish National Fund program for environmental studies.
Funding Information:
This study was funded by the PALEX project ?Paleohydrology and Extreme Floods from the Dead Sea ICDP core? of the DFG (grant no. BR2208/13-1/-2), and by the Center of Excellence of The Israel Science Foundation (grant No. 1436/14). Tomer Flax and Itamar Levitan had participated in the research as part of the Alpha program for gifted high school students and had contributed equally to this manuscript. The assistance of Adi Ticher, Ofir Tirosh, Prof. Nir Keren, Adam Levi, and Prof. Jonathan Erez are extremely appreciated. The members of the Dead Sea Observatory team of the Geological Survey of Israel (https://gsideadsea.wixsite.com/dso-gsi) are thanked for providing the Dead Sea brine. We are also grateful to Dr. Gadi Weiss and Prof. Aharon Kaplan for providing the EPS. Exchange of ideas, fruitful discussions, and assistance from Moshe (Koko) Armon, Ziv Mor, Drs. Nadav Lensky, Ido Sirota and Michael Beyth, and Profs. Aharon Oren, Boaz Lazar, Jonathan Erez are appreciated as well. We are also grateful for a detailed and useful colleague review by Prof. Abraham Starinsky and by two anonymous reviewers that substantially improved the manuscript. Yoav Ben Dor is grateful for scholarships from the Hebrew University Advanced School of Environmental Studies and the Rieger Foundation-Jewish National Fund program for environmental studies.
Publisher Copyright:
© 2021 Elsevier B.V.
Keywords
- Aragonite
- Dead Sea
- Dead Sea deep drilling project
- EPS
- Eastern Mediterranean
- Extracellular polymeric substances
- Lacustrine carbonate
- Lake Lisan
- Levant climate
- Paleoclimate
- Paleohydrology
- Paleolimnology
- Varves
