Two geoscientists at SUNY Potsdam have received a $411,477 grant from the U.S. National Science Foundation to investigate the chemistry of ancient waters preserved in sedimentary rocks across Atlantic Canada. The three-year project, led by Earth and environmental scientists Page Quinton and Michael Rygel, will examine rocks formed between approximately 419 million and 251 million years ago, during the Devonian through Permian periods. By determining whether ancient wetlands and coastal environments were freshwater, brackish or marine, the researchers hope to clarify how changing water chemistry influenced the early evolution of life on land and shaped the distribution of energy and mineral resources in the Maritimes Basin.
The project, titled “Salinity, Source Rocks, and Cyclothems: Using Paleosalinity Proxies to Track Marine Influence in the Maritimes Basin,” will take researchers into Nova Scotia, New Brunswick, Prince Edward Island and Newfoundland. The Maritimes Basin contains thousands of feet of sedimentary strata that record repeated changes in rivers, lakes, wetlands, coastal plains and shallow seas. These sequences, known as cyclothems when they preserve recurring sedimentary cycles, formed as environmental conditions shifted over immense periods of time. Sea-level fluctuations, tectonic activity and changes in climate repeatedly altered the balance between terrestrial and marine conditions, leaving behind layers that can now be studied for chemical evidence of those transitions.
The rocks are scientifically important far beyond their value as geological records. They contain evidence of a pivotal stage in Earth’s history, when organisms were establishing increasingly complex ecosystems on land. Fossils found in the region include trackways made by early amphibians, skeletal remains attributed to some of the oldest unequivocal reptiles, early land snails and remarkably preserved fossil forests. The rocks also preserve what may be the oldest evidence of parental care in synapsids, the evolutionary group that includes mammals and their extinct mammal-like relatives, as well as traces suggesting coordinated movement among groups of organisms across ancient landscapes. Yet the wetlands and lowland environments in which many of these organisms lived have remained chemically mysterious.
“Those environments could have been fresh, brackish, or marine—we have no idea,” Rygel said. “Geologists have been wondering about the chemistry of these wetlands for nearly 200 years.” The question matters because salinity can strongly influence which organisms are able to survive, reproduce and become preserved in the geological record. It can also affect sediment production, mineral formation and the preservation of organic material. A wetland periodically invaded by seawater would have supported a very different biological community from an isolated freshwater basin, even if the two environments appeared similar in the rock record.
Traditionally, geologists have attempted to estimate the salinity of ancient environments by identifying fossils associated with marine or freshwater conditions. In the Maritimes Basin, however, this strategy has produced only limited results despite nearly two centuries of investigation. The relevant organisms may not have lived in the environments being studied, may not have been preserved, or may have been excluded by chemical conditions that made survival difficult. Fossil evidence can also be unevenly distributed, making it dangerous to interpret a single discovery as representative of an entire sedimentary interval. The new project will use geochemical paleosalinity proxies—measurable chemical signatures that reflect the composition of the water and the conditions under which minerals formed—to analyze the rocks directly.
Quinton’s expertise in stable isotope geochemistry will be central to the investigation. Stable isotopes are nonradioactive forms of elements that can vary in predictable ways as water evaporates, minerals precipitate, organic matter accumulates or fluids mix. By measuring isotopic patterns and other chemical indicators in carefully selected minerals and sedimentary layers, researchers can reconstruct aspects of the waters that existed millions of years ago. These methods cannot provide a simple snapshot of an ancient landscape, but when combined with sedimentology, stratigraphy and fossil evidence, they can reveal whether marine water entered a basin, how persistent that influence was and how environmental conditions changed through time.
The results could also help explain why economically important resources occur where they do. The Maritimes Basin has supported more than 200 years of resource-based economic activity, including industries connected to coal and other geological materials. Understanding the origin and movement of ancient water can improve interpretations of how sedimentary rocks formed and how minerals, organic-rich deposits and other resources became concentrated. “Beyond its pure scientific value, gaining a better understanding of the chemistry of these ancient waters could potentially improve our understanding of the distribution of energy and mineral resources in this part of the world,” Quinton said. Some of the field sites are located along remote and rugged coastlines, including areas bordering the Bay of Fundy, where modern tides provide a dramatic reminder of the power of marine processes.
The investigation will be designed as an intensive undergraduate research experience as well as a scientific study. SUNY Potsdam students will participate in field mapping and sampling, laboratory preparation, geochemical analysis, data interpretation and the presentation of results. The project will also create opportunities for future K-12 Earth science teachers to gain direct experience with field and laboratory research. Rather than observing only one part of the process, students will work as members of a research team, linking geological theory learned in lectures with practical skills and real-world questions. Rygel said the experience will help students identify whether they are most interested in field-based research, laboratory work or a combination of both, while improving their preparation for graduate study and scientific careers.
The NSF award extends an established collaboration between Quinton and Rygel. In 2021, the pair received $370,113 through an NSF Research in Undergraduate Institutions grant to study ancient climate cycles while mentoring students during field investigations in Montana and Texas. They have also worked together on a campus Geoscience Garden and co-authored an open educational textbook for their students. Quinton studies the links among the carbon cycle, ancient climate change and major mass extinction events, including research that gained international attention after its publication in Science in 2018. Rygel is a sedimentologist and stratigrapher whose research focuses on Paleozoic rocks, ancient environments and the geological record associated with coal-bearing regions of the Appalachian and Maritimes basins, as well as ancient glacial deposits in Australia.
By combining newly developed geochemical techniques with detailed field observations, the SUNY Potsdam team aims to turn an enduring geological uncertainty into a measurable history of environmental change. Their work could identify intervals when marine waters penetrated inland wetlands, establish how long those incursions lasted and reveal whether major biological developments coincided with shifts in salinity. The findings may ultimately connect the chemistry of ancient water with the rise of terrestrial ecosystems, the preservation of exceptional fossils and the formation of economically valuable rocks. For a basin that records the moment when life was transforming the land, the chemistry hidden inside its minerals may provide one of the clearest clues to how that transformation unfolded.
Subject of Research: Ancient water chemistry, paleosalinity, marine influence, sedimentary rocks, cyclothems, Devonian-Permian environments, terrestrial evolution and resource geology in Atlantic Canada.
Article Title: NSF Grant Will Reveal the Salinity of Ancient Wetlands That Hosted Early Life on Land
Web References: https://www.potsdam.edu/academics/aas/depts/earth ; https://www.potsdam.edu/news/GeologyFacultyMembersAwardedNSFGrantResearch ; https://www.potsdam.edu/academics/aas/depts/earth/QuintonRygelTextbook
References: SUNY Potsdam announcement on the NSF-funded project; U.S. National Science Foundation; research statements from Page Quinton and Michael Rygel.
Image Credits: Dr. Page Quinton
Keywords: sedimentary rocks, paleosalinity, ancient water chemistry, Maritimes Basin, Devonian, Permian, Atlantic Canada, geology, geochemistry, cyclothems, marine influence, terrestrial evolution, fossils, SUNY Potsdam, National Science Foundation, undergraduate research
