{"doi":"10.2110/001c.56183","title":"Microbial Activity and Neomorphism Influence the Composition and Microfabric of Ooids From Great Salt Lake, UT","abstract":"The sediment along the shorelines of Great Salt Lake (GSL), Utah is dominated by ooids, concentrically-coated carbonate sand grains. Two characteristics differentiate GSL ooids from typical modern marine ooids: well-developed radial aragonite microfabrics and the ubiquitous occurrence of a Mg-silicate phase. The radial microfabrics have formed the basis of conceptual models applied to understand the formation of radial fabrics in ancient ooids, but the formation of the Mg-silicates, and the relationship between Mg-silicates and radial aragonite crystals have received little attention. The occurrence of Mg-silicates in GSL ooids is surprising because GSL lake water pH is ~8.3, too low for Mg-silicate precipitation (requires pH>8.7). We use transmitted light microscopy, element mapping via wavelength-dispersive x-ray spectroscopy with electron microprobe, scanning electron microscopy, and synchrotron x-ray fluorescence (XRF) mapping and sulfur K-edge absorption spectroscopy to explore the spatial relationships between the mineral phases in GSL ooids. We observe large euhedral aragonite crystals penetrating Mg-silicate zones and cutting across laminar cortices, suggesting that the characteristic radial aragonitic fabrics in GSL ooids, traditionally interpreted as a primary structure, are enhanced, or in some cases entirely created via neomorphism. XRF maps reveal that Mg-silicate zones co-occur with elemental sulfur (S 0 ), which we interpret as a metabolic intermediate of microbial sulfur cycling. This co-occurrence supports our hypothesis that microbial sulfur cycling plays a key role in the formation of GSL ooids by locally shifting pH beyond the threshold for Mg-silicate precipitation. This compositional fingerprint could serve as a biosignature in ancient lacustrine strata where Mg-silicates co-occur with carbonate minerals.","journal":"The Sedimentary Record","year":2022,"id":298450,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":6,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9502,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2022-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":312253,"name":"Samuel M. Webb","orcid":"0000-0003-1188-0464","position":1,"is_corresponding":false},{"id":987505,"name":"Theodore M. Present","orcid":"0000-0002-4747-2174","position":2,"is_corresponding":false},{"id":668321,"name":"John S. Magyar","orcid":"0000-0002-3586-8286","position":3,"is_corresponding":false},{"id":972299,"name":"Elizabeth J. Trower","orcid":"0000-0001-9898-5589","position":4,"is_corresponding":false},{"id":987504,"name":"Tyler A Lincoln","orcid":"0009-0000-8012-3104","position":0,"is_corresponding":true}],"reference_count":38,"raw_metadata":null,"created_at":"2026-07-19T00:31:36.269611Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}