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ORIGINAL RESEARCH article

Front. Earth Sci.
Sec. Quaternary Science, Geomorphology and Paleoenvironment
Volume 12 - 2024 | doi: 10.3389/feart.2024.1450001

Paleosalinity characteristics of the 1st Member in the Lower Cretaceous Prosopis Formation, Baobab North Sag, Bongor Basin

Provisionally accepted
XIANBING LI XIANBING LI 1KANG XIAO KANG XIAO 1*LONG SUN LONG SUN 2SHENGHE WU SHENGHE WU 2Zhenhua Xu Zhenhua Xu 2SICHONG JIANG SICHONG JIANG 2
  • 1 Research Institute of Petroleum Exploration and Development (RIPED), Beijing, China
  • 2 College of Geosciences, China University of Petroleum, Beijing, China

The final, formatted version of the article will be published soon.

    Paleosalinity is one of the important properties of paleolake water and is crucial for paleoenvironmental and paleoclimatic reconstruction. However, the paleosalinity characteristics of the 1st Member in the Lower Cretaceous Prosopis Formation (P1 Member) from the Baobab North Sag have not been systematically reported until now.In this study, 16 representative mudstone samples were collected from three coring wells and detailed elemental geochemical investigations were presented to reconstruct the salinity and water types for the P1 Member. The results show that the Sr/Ba ratios range from 0.32 to 0.93, indicating fresh water and brackish water, while the B/Ga ratios range from 1.6 to 3.4, also exhibiting the presence of fresh water and brackish water.The equivalent boron contents range from 84.3 ppm to 185 ppm, with the cast point located in the freshwater interval. Moreover, salinity values ranging from 1.2‰ to 11.0‰ for the Adams' paleosalimeter and from 6.1‰ to 9.3‰ for the Couch's paleosalimeter are indicative of brackish water, precisely mesohaline water. After sufficiently eliminating the interferences of diagenesis from the results, combined evaluation of evolutionary profiles and cross-plots of paleosalinity proxies suggest that the B/Ga ratio is the most important proxies for distinguishing water salinity types within the studied interval. The results of the B/Ga ratio indicate that the presence of two main water salinity types: fresh water (mainly distributed in the P1 4 and P1 2 sub-members) and brackish water (mainly distributed in the P1 3 and P1 1 sub-members). Furthermore, high salinity records in the study area correspond to arid climates, while low salinity intervals correspond to semi-arid and humid pulses, which provides a useful reference for the reconstruction of paleosalinity in terrestrial closed lake basins during the Cretaceous global warming period.

    Keywords: Paleosalinity, paleoclimate, paleosalinity proxy, Baobab North Sag, Prosopis Formation

    Received: 16 Jun 2024; Accepted: 04 Sep 2024.

    Copyright: © 2024 LI, XIAO, SUN, WU, Xu and JIANG. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: KANG XIAO, Research Institute of Petroleum Exploration and Development (RIPED), Beijing, China

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