MUD & GEOCHEM

TO UNDERSTAND EARTH'S EVOLUTION

I am Mariano Remírez and I am a Postdoctoral Researcher in the Department of Geosciences and Natural Resources Management at the University of Copenhagen. I am part of the Earth History and Geobiology research group led by Tais Dahl.

My work focuses on reconstructing paleoenvironmental and paleoclimatic conditions of the Earth through studies that involve stratigraphy, petrography, SEM, and geochemical analysis of fine-grained rocks and carbonates. But I am also interested in the history and philosophy of science, as well as education-related topics.

mnr@ign.ku.dk

News

Visit to China

I am really happy to have spent some time in China for the International Workshop on Mesozoic–Palaeogene Hyperthermal Events & the Fifth IGCP 739 Workshop, which wrapped up the IUGS–UNESCO IGCP 739 project that I am very glad to be part of. Special thanks to Xiumian Hu and Zhong Han for the kind invitation. It was a fantastic opportunity not only to discuss exciting science, but also to catch up with colleagues and finally meet in person some collaborators I’ve been working with for years. I’m also very grateful for the warm hospitality of our Chinese colleagues. Beyond the workshop, I had the chance to visit some iconic sites, including the Sun Yat-sen Mausoleum in Nanjing and the Great Wall in Beijing—truly unforgettable experiences!

Conference season

This summer, I had the pleasure of attending two inspiring conferences: the International Meeting of Sedimentology in Huelva, Spain, and the Goldschmidt Conference in Prague, Czech Republic. Both events were fantastic opportunities to share science, reconnect with friends and colleagues, and engage in meaningful discussions. I’m also grateful for the opportunity to serve our community through roles in the IAS Early Career Researcher Committee and on the Board of the Geochemical Society. These meetings were not only important scientific events—they also offered space for vital discussions about the future of our disciplines, collaboration, and how we support each other as researchers.

Research visit to Royal Holloway

Wrapping up a fantastic research visit to the Department of Earth Sciences, Royal Holloway University of London where I had the opportunity to work alongside Alex Dickson to collect uranium isotope data for my current project on past ocean global redox dynamics. Special thanks to Alex for being such a generous host including a wonderful trip to Lyme Regis, where we walked the same cliffs where Mary Anning discovered the first complete ichthyosaur almost 200 years ago.

New collaboration paper in Chemical Geology III

In this paper, we test the reliability of B/Ga ratios as a paleosalinity proxy across diverse sedimentary settings, from modern environments to Devonian shales. While boron uptake varies with clay content, normalization to Ga effectively removes this influence. We find no consistent relationship between B/Ga and specific clay minerals, suggesting that mineralogy generally does not bias B/Ga-based salinity reconstructions. These results support the broad applicability of B/Ga as a salinity proxy, with clay mineral analysis recommended as a complementary tool in select cases.

Appointment as Early Career Director on the Geochemical Society Board

I am honored to be elected as an Early Career Director on the Geochemical Society Board, the governing body of the Society. I sincerely thank all the members for their participation in the election. I am eager to contribute new perspectives to the board and help support our community.

New paper in Chemical Geology II

In our latest research, with input from colleagues across different institutions and countries, we explored the use of elemental salinity proxies (B/Ga, Sr/Ba, S/TOC) in various modern and Holocene environments, ranging from freshwater lakes to marine settings. Our findings show that these proxies are generally reliable (with a few exceptions!). We also found that factors like clay mineralogy have less of an impact than we expected. Overall, our work reinforces the value of these proxies for studying past salinity, while emphasizing the importance of context.

New paper in Chemical Geology!

In this paper, we reconstruct the history of connection and disconnection of an epeiric sea from the open ocean using redox and, primarily, salinity proxies. Analyzing the Cretaceous Agrio Formation (Argentina), we show that initial isolation of the Neuquén Basin led to hypersalinity and anoxia, followed by freshening, with later reconnection marked by a sharp salinity rise before marine fossils and transgressive surfaces appeared. Our findings reveal that salinity proxies are powerful tools for detecting marine-lacustrine transitions in fine-grained successions, even in the absence of fossils.

New collaboration paper in Sedimentology

As part of our efforts to reconstruct ancient epeiric seas, we have combined a comprehensive set of sedimentological and geochemical tools to trace the littoral drift of a Cretaceous shoreline. Using the well-studied deltaic and shoreface sandstones from the Pilmatué Member (Agrio Formation, Neuquén Basin, Argentina), we reconstruct the sand pathways along the shoreline and define this as a Sediment Routing Tract—a segment of the larger Sediment Routing System. Have a look into this multidisciplinary work that truly uses the present as the key to the past!

New project funded!

Thrilled to announce that we’ve been awarded an NSF grant to dive deeper into the history of ocean oxygen levels along with Geoff Gilleaudeau! We’re set to explore the dynamics of Devonian marine oxygenation, aiming to unlock new insights into how early ocean ecosystems adapted to big shifts in climate. Excited to get started on this journey that will bring us to Bolivia and Australia!

Appointment as IAS ECSC member

I am truly happy and honored to be appointed as a new member of the IAS Early Career Scientists Committee. This role comes with significant challenges, but I am eager to contribute my skills and previous experience to address them. I look forward to collaborating with the future generation of sedimentologists 💪💪💪

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