Geologic controls on phytoplankton elemental composition

Planktonic organic matter forms the base of the marine food web, and its nutrient content (C:N:Porg) governs material and energy fluxes in the ocean. Over Earth history, C:N:Porg had a crucial role in marine metazoan evolution and global biogeochemical dynamics, but the geologic history of C:N:Porg is unknown, and it is often regarded constant at the “Redfield” ratio of ∼106:16:1. We calculated C:N:Porg through Phanerozoic time by including nutrient- and temperature-dependent C:N:Porg parameterizations in a model of the long-timescale biogeochemical cycles. We infer a decrease from high Paleozoic C:Porg and N:Porg to present-day ratios, which stems from a decrease in the global average temperature and an increase in seawater phosphate availability. These changes in the phytoplankton’s growth environment were driven by various Phanerozoic events: specifically, the middle to late Paleozoic expansion of land plants and the Triassic breakup of the supercontinent Pangaea, which increased continental weatherability and the fluxes of weathering-derived phosphate to the oceans. The resulting increase in the nutrient content of planktonic organic matter likely impacted the evolution of marine fauna and global biogeochemistry.

Geologic controls on phytoplankton elemental composition

Planktonic organic matter forms the base of the marine food web, and its nutrient content (C:N:Porg) governs material and energy fluxes in the ocean. Over Earth history, C:N:Porg had a crucial role in marine metazoan evolution and global biogeochemical dynamics, but the geologic history of C:N:Porg is unknown, and it is often regarded constant at the “Redfield” ratio of ∼106:16:1. We calculated C:N:Porg through Phanerozoic time by including nutrient- and temperature-dependent C:N:Porg parameterizations in a model of the long-timescale biogeochemical cycles. We infer a decrease from high Paleozoic C:Porg and N:Porg to present-day ratios, which stems from a decrease in the global average temperature and an increase in seawater phosphate availability. These changes in the phytoplankton’s growth environment were driven by various Phanerozoic events: specifically, the middle to late Paleozoic expansion of land plants and the Triassic breakup of the supercontinent Pangaea, which increased continental weatherability and the fluxes of weathering-derived phosphate to the oceans. The resulting increase in the nutrient content of planktonic organic matter likely impacted the evolution of marine fauna and global biogeochemistry.

Population genomic analysis of the speckled dace species complex (Rhinichthys osculus) identifies three species-level lineages in California

The speckled dace ( Rhinichthys osculus ) is small cyprinid fish that is widespread in the Western USA. Currently treated as a single species, speckled dace consists of multiple evolutionary lineages that can be recognized as species and subspecies throughout its range. Recognition of taxonomic distinctiveness of speckled dace populations is important for developing conservation strategies. In this study, we collected samples of speckled dace from 38 locations in the American West, with a focus on California. We used RAD sequencing to extract thousands of SNPs across the genome from samples to identify genetic differences among seven California populations informally recognized as speckled dace subspecies: Amargosa, Owens, Long Valley, Lahontan, Klamath, Sacramento, and Santa Ana speckled dace. We performed principal component analysis, admixture analysis, estimated pairwise Fst, and constructed a phylogeny to explore taxonomic relationships among these groups and test if these subspecies warrant formal recognition. Our analyses show that the seven subspecies fit into three major lineages equivalent to species: western (Sacramento-Klamath), Santa Ana, and Lahontan speckled dace. Death Valley speckled dace were determined to be two lineages (Amargosa and Long Valley) within Lahontan speckled dace. Western and Lahontan speckled dace lineages had branches that can be designated as subspecies. These designations fit well with the geologic history of the region which has promoted long isolation of populations. This study highlights the importance of genetic analysis for conservation and management of freshwater fishes.

Microbial and Geochemical Evidence of Permafrost Formation at Mamontova Gora and Syrdakh, Central Yakutia

Biotracers marking the geologic history and permafrost evolution in Central Yakutia, including Yedoma Ice Complex (IC) deposits, were identified in a multiproxy analysis of water chemistry, isotopic signatures, and microbial datasets. The key study sections were the Mamontova Gora and Syrdakh exposures, well covered in the literature. In the Mamontova Gora section, two distinct IC strata with massive ice wedges were described and sampled, the upper and lower IC strata, while previously published studies focused only on the lower IC horizon. Our results suggest that these two IC horizons differ in water origin of wedge ice and in their cryogenic evolution, evidenced by the differences in their chemistry, water isotopic signatures and the microbial community compositions. Microbial community similarity between ground ice and host deposits is shown to be a proxy for syngenetic deposition and freezing. High community similarity indicates syngenetic formation of ice wedges and host deposits of the lower IC horizon at the Mamontova Gora exposure. The upper IC horizon in this exposure has much lower similarity metrics between ice wedge and host sediments, and we suggest epigenetic ice wedge development in this stratum. We found a certain correspondence between the water origin and the degree of evaporative transformation in ice wedges and the microbial community composition, notably, the presence of Chloroflexia bacteria, represented by Gitt-GS-136 and KD4-96 classes. These bacteria are absent at the ice wedges of lower IC stratum at Mamontova Gora originating from snowmelt, but are abundant in the Syrdakh ice wedges, where the meltwater underwent evaporative isotopical fractionation. Minor evaporative transformation of water in the upper IC horizon of Mamontova Gora, whose ice wedges formed by meltwater that was additionally fractionated corresponds with moderate abundance of these classes in its bacterial community.

Redwood National and State Parks: Geologic resources inventory report

Comprehensive park management to fulfill the NPS mission requires an accurate inventory of the geologic features of a park unit, but Comprehensive park management to fulfill the NPS mission requires an accurate inventory of the geologic features of a park unit, but park managers may not have the needed information, geologic expertise, or means to complete such an undertaking; therefore, the Geologic Resources Inventory (GRI) provides information and resources to help park managers make decisions for visitor safety, planning and protection of infrastructure, and preservation of natural and cultural resources. Information in the GRI report may also be useful for interpretation. park managers may not have the needed information, geologic expertise, or means to complete such an undertaking; therefore, the Geologic Resources Inventory (GRI) provides information and resources to help park managers make decisions for visitor safety, planning and protection of infrastructure, and preservation of natural and cultural resources. Information in the GRI report may also be useful for interpretation. This report synthesizes discussions from a scoping meeting for Redwood National and State Parks (referred to as the “parks” throughout this report) held in 2004 and a follow-up conference call in 2019. Two GRI–compiled GIS data sets of the geology and geohazards of the parks are the principal deliverables of the GRI. The GRI GIS data are available on the GRI publications website http://go.nps.gov/gripubs and through the NPS Integrated Resource Management Applications (IRMA) portal https://irma.nps.gov/App/Portal/Home. Enter “GRI” as the search text and select a park from the unit list. Writing of this report was based on those data and the interpretations of the source map authors (see “GRI Products” and “Acknowledgements”). A geologic map poster illustrates the geology GRI GIS data set and serves as a primary figure for this GRI report. No poster was prepared for the geohazards GRI GIS data set. Additionally, figure 7 of this report illustrates the locations of the major geologic features in the parks. Unlike the poster, which is divided into a northern and southern portion to show detail while accommodating the parks’ length, figure 7 is a single-page, simplified map. The features labeled on figure 7 are discussed in the “Geologic History, Features, and Processes” chapter. To provide a context of geologic time, this report includes a geologic time scale (see "Geologic History, Features, and Processes"). The parks’ geologic story encompasses 200 million years, starting in the Jurassic Period. Following geologic practice, the time scale is set up like a stratigraphic column, with the oldest units at the bottom and the youngest units at the top. Organized in this manner, the geologic time scale table shows the relative ages of the rock units that underlie the parks and the unconsolidated deposits that lie at the surface. Reading the “Geologic Event” column in the table, from bottom to top, will provide a chronologic order of the parks’ geologic history. The time scale includes only the map units within the parks that also appear on the geologic map poster; that is, map units of the geohazards data are not included. Geology is a complex science with many specialized terms. This report provides definitions of geologic terms at first mention, typically in parentheses following the term. Geologic units in the GRI GIS data are referenced in this report using map unit symbols; for example, map unit KJfrc stands for the Cretaceous (K) and Jurassic (J) Franciscan Complex (f), Redwood Creek schist (rc), which underlies a portion of the Redwood Creek watershed (see “GRI Products”).

Arc versus river—The geology of the Columbia River Gorge

ABSTRACT The Columbia River Gorge is the Columbia River’s long-held yet evolving passage through the volcanic arc of the Cascade Range. The globally unique setting of a continental-scale river bisecting an active volcanic arc at the leading edge of a major plate boundary creates a remarkable setting where dynamic volcanic and tectonic processes interact with diverse and energetic fluvial processes. This three-day field trip explores several elements of the gorge and its remarkable geologic history—cast here as a contest between regional tectonic and volcanic processes building and displacing landscapes, and the relentless power of the Columbia River striving to maintain a smooth passage to the sea. DEDICATION Dedicated to Russell C. Evarts (7 April 1947–11 July 2017) and his contributions to Pacific Northwest geology. Russ Evarts devoted most of his 30-year career with the U.S. Geological Survey to geologic mapping of Oregon and Washington. His thorough geologic mapping of the near-vertical terrain of the western Columbia River Gorge underpins much of what is reported in this guide and continues to inspire our studies of the geology of the Pacific Northwest.

Is geoheritage a “cutting-edge” science? Promotion of an extension to the definition of geoheritage with emphasis as a significant discipline in geosciences with cultural and societal relevance

ABSTRACT Geoheritage documentation is critical for the academic community, and thus incurs an expense to the general public, who may or may not feel the need to fund such an “academic” database. Fortunately, this documentation helps foster appreciation of geosites within a geotouristic framework and can inspire a nationalistic sense of pride, thus bringing about an economic incentive to countries actively involved in geoheritage research and documentation. Yet there remains a prejudice within academia that geoheritage is a descriptive field, is arbitrarily qualitative, and lacks the capacity to create new and important scientific discoveries. We present herein a description and discussion of the results of applying “cutting-edge” science in a geoheritage framework with ample examples from Greece and two case studies of its application. The first of these is The Aliakmon Legacy Project of Northern Greece that necessitated modern documentation to preserve its heritage base when plate tectonic global geoheritage localities were flooded. The second summarizes the geologic history of the Meteora World Heritage Site with an emphasis on how its long complex geologic history ultimately resulted in the Byzantine Monastic community. We propose this paper as a discussion model for the integration of primary geologic research with cultural heritage localities and emphasize that these promise to elevate geoheritage studies to a scale critical for documentation of human civilization itself. It is our opinion that geoheritage is capable of becoming a dynamic field of study in which documentation and preservation expands to integrate renewed multidisciplinary research that in turn comprises the scientific foundation of a “new” cutting-edge geologic field of study.

Amsassia (calcareous alga) from the Lower Ordovician (Tremadocian) of western Newfoundland, and the biologic affinity and geologic history of the genus

Modular coral-like fossils from Lower Ordovician (Tremadocian) thrombolitic mounds in the St. George Group of western Newfoundland were initially identified as Lichenaria and thought to include the earliest tabulate corals. They are here assigned to Amsassia terranovensis n. sp. and Amsassia? sp. A from the Watts Bight Formation, and A. diversa n. sp. and Amsassia? sp. B from the overlying Boat Harbour Formation. Amsassia terranovensis n. sp. and A. argentina from the Argentine Precordillera are the earliest representatives of the genus. Amsassia is considered to be a calcareous alga, possibly representing an extinct group of green algae. The genus originated and began to disperse in the Tremadocian, during the onset of the Great Ordovician Biodiversification Event, on the southern margin of Laurentia and the Cuyania Terrane. It inhabited small, shallow-marine reefal mounds constructed in association with microbes. The paleogeographic range of Amsassia expanded in the Middle Ordovician (Darriwilian) to include the Sino-Korean Block, as well as Laurentia, and its environmental range expanded to include non-reefal, open- and restricted-marine settings. Amsassia attained its greatest diversity and paleogeographic extent in the Late Ordovician (Sandbian–Katian), during the culmination of the Great Ordovician Biodiversification Event. Its range included the South China Block, Tarim Block, Kazakhstan, and Siberia, as well as the Sino-Korean Block and Laurentia, and its affinity for small microbial mounds continued during that time. In the latest Ordovician (Hirnantian), the diversity of Amsassia was reduced, its distribution was restricted to non-reefal environments in South China, and it finally disappeared during the end-Ordovician mass extinction. UUID: http://zoobank.org/ef0abb69-10a6-46de-8c78-d6ec7de185fe

“But why paint a dinosaur blue?”: Envisioning the Cretaceous— A vitalizing, multidisciplinary project in a university museum

ABSTRACT In 2017–2018, two fine arts undergraduate students, Todd Rowan and Moesha Wright, conceived and created a mural for the Dunn-Seiler Museum at Mississippi State University, Mississippi, USA, under the supervision of art professor emeritus Brent Funderburk. Students researched, conceptualized, and painted Mississippi Cretaceous Panorama, which interpreted the Late Cretaceous landscape that once surrounded the university and the momentous extinction event that brought the Mesozoic Era to its close. The project necessitated creativity to address several chal lenges, including funding, space constraints, and a local population with Young Earth views. The completed mural engages museum visitors with a mosasaur, ceratopsian dinosaur, and a meteorite impact—illustrating the local, terminal Mesozoic geologic history in a nonthreatening venue that can improve community geoliteracy.