UNUSUAL FOSSILIFEROUS CONCRETIONS FROM LACUSTRINE DEPOSITS IN THE LOWER JURASSIC MOENAVE FORMATION IN ST. GEORGE, UTAH, USA: IMPLICATIONS FOR ANCIENT FISH MASS MORTALITIES

ABSTRACT Two types of unusual concretions with similar biotic contents but markedly different shapes and distributions were found in close stratigraphic proximity within the Lower Jurassic Whitmore Point Member of the Moenave Formation in St. George, Utah. Both types of concretions formed in lacustrine sediments and contain abundant ganoid fish scales, numerous ostracode carapaces, and apparent rip-up clasts. Elongate, cylindrical concretions developed in parallel and regularly spaced rows in one horizon, and comparatively flat and irregularly shaped and distributed concretions formed in an overlying layer only a few centimeters above. Microprobe and Raman analyses of concretion samples reveal abundant hematite in both concretions as well as groundmass minerals dominated by silica in the cylindrical concretions and dolomite in the flat concretions. The abundance of fish skeletal debris in concretions from two consecutive horizons may suggest recurring fish mass mortality in ancient Lake Dixie, the large lake that occupied the St. George area during the Early Jurassic. We propose a model for the formation of the concretions based on their shapes, distributions, and chemistry. In this model, accumulations of disarticulated fish debris were colonized and consolidated by microbial mats and shaped by oscillatory flow (in the case of the cylindrical concretions) or lack thereof (in the case of the flat concretions). Then, after burial, groundwater chemistry and possibly the metabolic activities of microorganisms led to the precipitation of minerals around and within the masses of fish material. Finally, diagenetic alteration changed the mineral makeups of the cylindrical and flat concretions into what they are today.

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The ‘Last Hurrah of the Reigning Darwinulocopines’? Ostracoda (Arthropoda, Crustacea) from the Lower Jurassic Moenave Formation, Arizona and Utah, USA

Journal of Paleontology ◽

10.1017/jpa.2017.150 ◽

2018 ◽

Vol 92 (4) ◽

pp. 648-660 ◽

Cited By ~ 3

Author(s):

Lucas S. Antonietto ◽

Lisa E. Park Boush ◽

Celina A. Suarez ◽

Andrew R.C. Milner ◽

James I. Kirkland

Keyword(s):

Asexual Reproduction ◽

Fossil Record ◽

Late Jurassic ◽

Lacustrine Sediments ◽

Lower Jurassic ◽

Late Triassic ◽

Geographical Isolation ◽

Central Atlantic Magmatic Province ◽

Central Atlantic ◽

Moenave Formation

AbstractAn ostracode fauna is described from lacustrine sediments of the Hettangian, Lower Jurassic, Whitmore Point Member of the Moenave Formation. The Moenave is well known for its rich, Late Triassic?–Early Jurassic fossil record, which includes fossil fishes, stromatolites, ostracodes, spinicaudatans, and a diverse ichnofauna of invertebrates and vertebrates. Four ostracode species, all belonging to the suborder Darwinulocopina, were recovered from these sediments:Suchonellina globosa,S. stricta,Whipplella? sp. 1, andW.? sp. 2. The diversity and composition of the Whitmore Point Member ostracode fauna agree with previous interpretations about Lake Dixie and nearby paleoenvironments as shallow lakes inhabited by darwinulocopine species that survived the effects of the Central Atlantic Magmatic Province and the subsequent end-Triassic extinction and quickly recolonized these areas, thanks to asexual reproduction by parthenogenesis. The Lake Dixie region, in its geographical isolation, could represent the last episode of darwinulocopine dominance in nonmarine environments before the Late Jurassic diversification of the cypridocopine/cytherocopine modern ostracodes.

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Deposition and deformation of fluvial–lacustrine sediments of the Upper Triassic–Lower Jurassic Whitmore Point Member, Moenave Formation, northern Arizona

Sedimentary Geology ◽

10.1016/j.sedgeo.2009.11.010 ◽

2010 ◽

Vol 223 (1-2) ◽

pp. 180-191 ◽

Cited By ~ 12

Author(s):

Lawrence H. Tanner ◽

Spencer G. Lucas

Keyword(s):

Lacustrine Sediments ◽

Lower Jurassic ◽

Upper Triassic ◽

Northern Arizona ◽

Moenave Formation

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Transcriptomic evidence for versatile metabolic activities of mercury cycling microorganisms in brackish microbial mats

npj Biofilms and Microbiomes ◽

10.1038/s41522-021-00255-y ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Adrien Vigneron ◽

Perrine Cruaud ◽

Johanne Aubé ◽

Rémy Guyoneaud ◽

Marisol Goñi-Urriza

Keyword(s):

Microbial Mats ◽

Food Chains ◽

Mercury Cycling ◽

Aquatic Life ◽

A Genome ◽

Large Panel ◽

Different Populations ◽

Halogen Compound ◽

Metabolic Activities

AbstractMethylmercury, biomagnifying through food chains, is highly toxic for aquatic life. Its production and degradation are largely driven by microbial transformations; however, diversity and metabolic activity of mercury transformers, resulting in methylmercury concentrations in environments, remain poorly understood. Microbial mats are thick biofilms where oxic and anoxic metabolisms cooccur, providing opportunities to investigate the complexity of the microbial mercury transformations over contrasted redox conditions. Here, we conducted a genome-resolved metagenomic and metatranscriptomic analysis to identify putative activity of mercury reducers, methylators and demethylators in microbial mats strongly contaminated by mercury. Our transcriptomic results revealed the major role of rare microorganisms in mercury cycling. Mercury methylators, mainly related to Desulfobacterota, expressed a large panel of metabolic activities in sulfur, iron, nitrogen, and halogen compound transformations, extending known activities of mercury methylators under suboxic to anoxic conditions. Methylmercury detoxification processes were dissociated in the microbial mats with methylmercury cleavage being carried out by sulfide-oxidizing Thiotrichaceae and Rhodobacteraceae populations, whereas mercury reducers included members of the Verrucomicrobia, Bacteroidetes, Gammaproteobacteria, and different populations of Rhodobacteraceae. However most of the mercury reduction was potentially carried out anaerobically by sulfur- and iron-reducing Desulfuromonadaceae, revising our understanding of mercury transformers ecophysiology.

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Posterolateral markings on dinosaur tracks, Cameron Dinosaur Tracksite, Lower Jurassic Moenave Formation, northeastern Arizona

Journal of Paleontology ◽

10.1017/s0022336000035289 ◽

1995 ◽

Vol 69 (4) ◽

pp. 779-784 ◽

Cited By ~ 10

Author(s):

Grace V. Irby

Keyword(s):

New Mexico ◽

Sexual Dimorphism ◽

Lower Jurassic ◽

Dinosaur Tracks ◽

Size And Morphology ◽

Working Hypotheses ◽

Moenave Formation

Posterolateral markings, appearing as short, rectilinear grooves projecting from the posterior margins of digit IV, occur on tracks in five of 34 trackways at the Cameron Dinosaur Tracksite in the Dinosaur Canyon Member of the Lower Jurassic Moenave Formation, northeastern Arizona. A new ichnospecies, Grallator (Anchisauripus) madseni, is described from these five trackways made by bipedal, tridactyl dinosaurs. The size and morphology of the tracks suggest that they may represent trackmakers similar to Coelophysis and Syntarsus, two dinosaurs described from Triassic and Jurassic deposits in northeastern Arizona and northwestern New Mexico.Among the working hypotheses cited as possible causes of the posterolateral markings are: 1) they were made by the dragging of digit III or of the metatarsus; 2) they are marks produced by a feature similar to a horny excrescence or cornified ridge on digitometatarsal pad IV; and 3) they are related to a peculiarity that may have resulted from sexual dimorphism.

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Biogeochemical Characteristics of Lacustrine Sediments Reflecting a Changing Alpine Neotropical Ecosystem during the Pleistocene

Quaternary Research ◽

10.1006/qres.2002.2369 ◽

2002 ◽

Vol 58 (2) ◽

pp. 189-196 ◽

Cited By ~ 6

Author(s):

Germán Mora ◽

Lisa M. Pratt ◽

Arnoud Boom ◽

Henry Hooghiemstra

Keyword(s):

Algal Blooms ◽

Lacustrine Sediments ◽

Organosulfur Compounds ◽

Alpine Ecosystems ◽

Tropical Andes ◽

Isotopic Signatures ◽

Climatic Variations ◽

Lacustrine Deposits ◽

Reducing Conditions ◽

Vegetation Expansion

AbstractContinuous lacustrine deposits of the Funza-II core from the Bogotá basin, Colombia (5°N74°W) record late Pleistocene climatic variations, providing an opportunity to assess the influence of glacial–interglacial climate changes on alpine ecosystems in equatorial South America. Biogeochemical response of this tropical alpine system to climate change was inferred from changes in elemental concentrations and ratios and isotopic signatures in the upper 120 m of the lacustrine Funza core.Values of δ13Corg exhibit eight abrupt, positive shifts that are thought to reflect rapid expansions of C4 grasses in the tropical Andes and algal blooms. One of these excursions, interpreted to correspond to C4 vegetation expansion, occurred in sediments accumulated during the last glaciation (∼30,000–50,000 yr B.P.) and implies a downslope shift of the upper Andean treeline, regardless of prevailing temperatures.Sedimentary carbon/sulfur ratios are low and indicate significant sequestering of sulfur. Monosulfides are the dominant constituent of sedimentary sulfur during relatively humid intervals, when increased supply of iron caused by enhanced weathering favored the formation of monosulfide minerals under strongly reducing conditions. In contrast, organosulfur compounds dominate the sedimentary sulfur-species in relatively drier intervals when mildly reducing conditions and limited iron input promoted the diagenetic incorporation of sulfur in organic matter. Dry events inferred from the sulfur record typically correlate with glacial maxima, whereas glacial terminations are usually associated with wet periods.

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Diatomaceous origin of siliceous shale in Eocene lake beds of central British Columbia

Canadian Journal of Earth Sciences ◽

10.1139/e04-099 ◽

2005 ◽

Vol 42 (2) ◽

pp. 231-241 ◽

Cited By ~ 15

Author(s):

George E Mustoe

Keyword(s):

British Columbia ◽

Lacustrine Sediments ◽

X Ray Diffraction ◽

Element Geochemistry ◽

X Ray ◽

Diagenetic Alteration ◽

Extant Species ◽

Geologic Record ◽

Siliceous Shale ◽

Lake Beds

The abundance of diatoms in Neogene lacustrine sediments and their apparent scarcity in Paleogene deposits have long perplexed geoscientists, but siliceous shales from Eocene lake beds of central British Columbia provide new insights. Major element geochemistry, X-ray diffraction patterns, and relict diatom frustules suggest that Eocene beds at Horsefly, McAbee, and Princeton originated as lacustrine diatomite that underwent diagenetic alteration to produce siliceous shale. The combination of high SiO2 and low Al2O3 values and the presence of opal-CT X-ray diffraction peaks provide a distinctive geochemical fingerprint for biogenic silica deposits that have been remineralized. The discovery of diatomaceous geochemical signatures in siliceous shales may prove to be a useful tool for extending the geologic record of diatoms, perhaps helping to reduce the apparent discrepancy between fossil evidence and evolutionary interpretations based extant species.

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Diagenetic alteration of basaltic tephra in lacustrine deposits, southwestern Idaho and southeastern Oregon

Open-File Report ◽

10.3133/ofr96697 ◽

1996 ◽

Cited By ~ 1

Author(s):

R.A. Sheppard

Keyword(s):

Lacustrine Deposits ◽

Diagenetic Alteration

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Diversity and Stratification of Archaea in a Hypersaline Microbial Mat

Applied and Environmental Microbiology ◽

10.1128/aem.01811-08 ◽

2008 ◽

Vol 75 (7) ◽

pp. 1801-1810 ◽

Cited By ~ 68

Author(s):

Charles E. Robertson ◽

John R. Spear ◽

J. Kirk Harris ◽

Norman R. Pace

Keyword(s):

Microbial Mats ◽

Pcr Primers ◽

Microbial Mat ◽

Rrna Genes ◽

Universal Primers ◽

Rrna Gene ◽

Ocean Water ◽

Chemical Gradients ◽

Specific Pcr ◽

Metabolic Activities

ABSTRACT The Guerrero Negro (GN) hypersaline microbial mats have become one focus for biogeochemical studies of stratified ecosystems. The GN mats are found beneath several of a series of ponds of increasing salinity that make up a solar saltern fed from Pacific Ocean water pumped from the Laguna Ojo de Liebre near GN, Baja California Sur, Mexico. Molecular surveys of the laminated photosynthetic microbial mat below the fourth pond in the series identified an enormous diversity of bacteria in the mat, but archaea have received little attention. To determine the bulk contribution of archaeal phylotypes to the pond 4 study site, we determined the phylogenetic distribution of archaeal rRNA gene sequences in PCR libraries based on nominally universal primers. The ratios of bacterial/archaeal/eukaryotic rRNA genes, 90%/9%/1%, suggest that the archaeal contribution to the metabolic activities of the mat may be significant. To explore the distribution of archaea in the mat, sequences derived using archaeon-specific PCR primers were surveyed in 10 strata of the 6-cm-thick mat. The diversity of archaea overall was substantial albeit less than the diversity observed previously for bacteria. Archaeal diversity, mainly euryarchaeotes, was highest in the uppermost 2 to 3 mm of the mat and decreased rapidly with depth, where crenarchaeotes dominated. Only 3% of the sequences were specifically related to known organisms including methanogens. While some mat archaeal clades corresponded with known chemical gradients, others did not, which is likely explained by heretofore-unrecognized gradients. Some clades did not segregate by depth in the mat, indicating broad metabolic repertoires, undersampling, or both.

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