Post-impact depositional environments as a proxy for crater morphology, Late Devonian Alamo impact, Nevada

ABSTRACT Conformable limestone deposits bracketing the Alamo breccia (Late Devonian, Nevada) provide a robust dataset for comparisons of depositional environments and marine communities before and after a significant meteor impact. Rank abundances of more than 3000 faunal identifications from 158 sampling localities cluster in three major faunal groups that are arranged in an onshore-offshore lithofacies gradient. Comparison of faunal clusters before and after the impact show little to no dissimilarity. The recovery of marine invertebrate communities following the Alamo impact event was geologically instantaneous. Broad geographic ranges of the fauna may have contributed to ecological resilience. From a geologic perspective, marine communities appear to rebound quickly and fully following meteor impacts, leaving impact-related extinctions as outliers that correspond only to the largest impacts.

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Palaeoenvironments and palynofacies of a pulsed transgression: the late Devonian and early Dinantian (Lower Carboniferous) rocks of southeast Wales

Geological Magazine ◽

10.1017/s0016756800017623 ◽

1991 ◽

Vol 128 (4) ◽

pp. 355-380 ◽

Cited By ~ 10

Author(s):

J. R. Davies ◽

A. McNestry ◽

R. A. Waters

Keyword(s):

Coastal Plain ◽

Depositional Environments ◽

Late Devonian ◽

Lower Carboniferous ◽

Palynological Analysis ◽

Red Sandstone ◽

South Wales ◽

Kerogen Type ◽

Event Stratigraphy ◽

Size Sorting

AbstractTwo boreholes in the Vale of Glamorgan have provided new data on the nature of the early Dinantian (Courceyan) transgression in South Wales. This transgression is manifested by the transition from the largely fluviatile, late Devonian, Upper Old Red Sandstone (Quartz Conglomerate Group) to the predominantly marine, early Dinantian, Lower Limestone Shale Group. The marine sequence comprises five shoaling upwards cycles, constructed from a suite of sedimentary lithofacies which record deposition in environments ranging from coastal plain, peritidal, lagoon, barrier and embayment to subtidal, open marine shelf. Each cycle represents a pulse of the transgression, and each successive pulse appears to have been larger than the preceding one, introducing progressively less restricted and more distal marine environments.Thirty-seven samples were processed for palynological analysis. Miospore biozonation supports the cycle correlations between the two boreholes, suggested by the sedimentary event stratigraphy. Detrital kerogens from the samples comprise both terrestrially derived and marine types in varying proportions. Each kerogen type is described as well as the size, sorting and preservation of each assemblage. A palynofacies profile is presented for eachof the depositional environments recognized.

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VERTEBRATE TAPHONOMY, PALEONTOLOGY, SEDIMENTOLOGY, AND PALYNOLOGY OF A FOSSILIFEROUS LATE DEVONIAN FLUVIAL SUCCESSION, CATSKILL FORMATION, NORTH-CENTRAL PENNSYLVANIA, USA

Palaios ◽

10.2110/palo.2020.005 ◽

2020 ◽

Vol 35 (11) ◽

pp. 470-494

Author(s):

DAVID R. BROUSSARD ◽

CAYLA J. TREASTER ◽

JEFFREY M. TROP ◽

EDWARD B. DAESCHLER ◽

PIERRE A. ZIPPI ◽

...

Keyword(s):

Depositional Environments ◽

Late Devonian ◽

North Central ◽

Central Pennsylvania ◽

Bone Fragments ◽

Bivalve Shell ◽

Floodplain Deposits ◽

Stratigraphic Succession ◽

Channel Bar ◽

Vertebrate Taphonomy

ABSTRACT The fluvial facies of the Catskill Formation record important ecological events that occurred during Late Devonian time. A well-exposed section between the towns of Blossburg and Covington, in north-central Pennsylvania, contains abundant macrofossils and sedimentary features, making it well-suited for linking Upper Devonian fossil occurrences with depositional environments and sedimentary processes. Strata consist of two distinct fluvial facies: floodplain lithofacies consist of mudrocks, with evidence of pedogenic overprinting and sharp-based sandstones interpreted as crevasse splays; channel-bar lithofacies consist of single- and multi-storied cross-stratified lenticular sandstone bodies interpreted as fluvial channel-bar complexes. Macrofossils occur in 22 discrete horizons spanning > 240 m of stratigraphic succession that include Archanodon bivalve shell impressions, two genera of “placoderms” (Bothriolepis, Phyllolepis), an unidentified acanthodian, and several taxa of sarcopterygian fishes, including lungfish (Dipnoi indet.), Holoptychius, Langlieria, and Sauripterus. Most vertebrate macrofossils are preserved as disarticulated, abraded plates, scales, and bone fragments in sandstone channel-bar deposits. Articulated, unabraded remains are preserved in proximal floodplain deposits. Miospores recovered from Catskill Formation fossil sites in the Blossburg-Covington section belong to the COR subzone of the VCo (Diducites versabilis-Grandispora cornuta) palynological zone, indicating deposition ca. 362 to 361.8 Ma during the late Famennian stage of the Late Devonian. Catskill Formation fluvial strata exposed tens of kilometers to the south and west yield latest Famennian palynomorphs. These broadly contemporaneous continental depositional environments supported Late Devonian vertebrate evolution, including the fin-to-limb transition in tetrapodomorphs, and the possible euryhalinity of vertebrates occupying marine-to-nonmarine transitional habitats.

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Paleoecology and Predominance Facies of Late Devonian Foraminifera in Successions of the Catskill Delta Complex, Western New York, U.S.A.

The Journal of Foraminiferal Research ◽

10.2113/gsjfr.51.1.32 ◽

2021 ◽

Vol 51 (1) ◽

pp. 32-45

Author(s):

Isabelle Li ◽

Kimberly Bartlett ◽

Cody Kowalski ◽

Paul Bembia ◽

Kimberly C. Meehan

Keyword(s):

New York ◽

Depositional Environment ◽

Appalachian Basin ◽

Depositional Environments ◽

Species Level ◽

Late Devonian ◽

Feeding Mode ◽

Mode Identification ◽

Crisis Events ◽

Depth Zonation

ABSTRACT Beyond yielding signals of extinction or stressed ecological conditions, modern and ancient foraminiferal assemblages reflect specific marine depositional environments and depths. Foraminiferal predominance facies and benthic foraminiferal depth zonation has been successfully used to identify specific marine environments dating back to the Carboniferous. Using insights from modern equivalents, correlative assemblages allow for paleoecological analysis and insights. Middle to Late Devonian (Frasnian) black and gray shale beds of western New York contain hundreds of diminutive calcareous and agglutinated foraminifera. The genera within these beds are reminiscent of shallow modern predominance facies. These foraminiferal assemblages and their associated predominance facies correlate well with prior lithologic and geochemical investigations that establish this portion of the Appalachian Basin as a deltaic setting but suggest it is likely inner neritic zone. Dominant genera include several species of Ammobaculites and Saccammina which suggest that paleodepths did not exceed 50 m throughout the Frasnian. Opportunistic genera reflect a muted crisis associated with the punctata isotopic event (Rhinestreet Event) and Lower Kellwasser (Pipe Creek) events. While there are definite shifts in the diversity of assemblages between gray and black shale, the foraminiferal type and feeding mode, indicative of depth and oxygen availability respectively, there is little variation between the distinct shale units. No significance was found between total organic carbon and foraminiferal type of feeding mode. Identification at the species level is problematic but assemblages at the genus-level suggest that the depositional environment was stressed. However, the effects of these marine crisis events were not significant for these foraminifera in comparison to those frequently reported; we found no local extinction for foraminifera at least through the lower Hanover Shale, just prior to the Hangenberg marine crisis event, within this deltaic complex of the Appalachian Basin in western New York.

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The Hushoot Shiveetiin gol section (Baruunhuurai Terrane, Mongolia): sedimentology and facies from a Late Devonian island arc setting

Palaeobiodiversity and Palaeoenvironments ◽

10.1007/s12549-020-00445-0 ◽

2020 ◽

Author(s):

A. Munkhjargal ◽

P. Königshof ◽

S. Hartenfels ◽

U. Jansen ◽

A. Nazik ◽

...

Keyword(s):

Depositional Environments ◽

Late Devonian ◽

Pyroclastic Deposits ◽

Central Asian ◽

Environmental Setting ◽

Plant Remains ◽

Extinction Event ◽

Conodont Stratigraphy ◽

Arc Setting ◽

Abundance And Diversity

Abstract A Late Devonian to (?)Early Mississippian section at Hushoot Shiveetiin gol in the Baruunhuurai Terrane of the Central Asian Orogenic Belt (CAOB) exposes large parts of cyclic Famennian shallow-water siliciclastic shelf deposits composed of siltstones, sandstones, shales, volcaniclastics, and intercalated autochthonous carbonates. The youngest part of the section, possibly Early Mississippian, is represented by arkosic sandstones with large plant remains. The facies reflects a range from shallow-intertidal to outer ramp settings. In terms of conodont stratigraphy, the Hushoot Shiveetiin gol section ranges from the Palmatolepis minuta minuta Biozone to at least the Palmatolepis rugosa trachytera Biozone. Hiatuses of several conodont biozones occur due to the facies setting (erosion and reworked sediments which are recognized by reworked conodonts) rather than thrusting or folding. The environmental setting was characterized by coeval subaerial volcanism resulting in numerous pyroclastic deposits. The depositional environments and intense volcanic activity at the Hushoot Shiveetiin gol section limited the stratigraphic distribution, abundance, and diversity of many elements of the fauna such as brachiopods. Ostracods were very abundant and diverse through many parts of the section. Although limited in stratigraphic distribution, the crinoid fauna is the most diverse Palaeozoic fauna collected from Mongolia to date and supports the hypothesis that the CAOB was a biodiversity hotspot in the aftermath of the Frasnian–Famennian extinction event.

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Depositional environments and sequence stratigraphy of the Bahram Formation (middle–late Devonian) in north of Kerman, south-central Iran

Geoscience Frontiers ◽

10.1016/j.gsf.2015.07.002 ◽

2016 ◽

Vol 7 (5) ◽

pp. 821-834 ◽

Cited By ~ 8

Author(s):

Afshin Hashmie ◽

Ali Rostamnejad ◽

Fariba Nikbakht ◽

Mansour Ghorbanie ◽

Peyman Rezaie ◽

...

Keyword(s):

Sequence Stratigraphy ◽

Depositional Environments ◽

Central Iran ◽

Late Devonian ◽

South Central ◽

Bahram Formation

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Stratigraphy and depositional environments of the Upper Mississippian Codroy Group: Port au Port Peninsula, western Newfoundland

Canadian Journal of Earth Sciences ◽

10.1139/e89-094 ◽

1989 ◽

Vol 26 (6) ◽

pp. 1089-1100 ◽

Cited By ~ 8

Author(s):

George R. Dix ◽

Noel P. James

Keyword(s):

Nova Scotia ◽

Depositional Environments ◽

Late Devonian ◽

Red Beds ◽

Freshwater Runoff ◽

Carbonate Buildups ◽

Formed Part ◽

Key Indicators ◽

Lithostratigraphic Correlation

Upper Mississippian (middle Viséan) biohermal limestones, siliciclastics, evaporites, and red beds of the lower Codroy Group (correlative with the lower Windsor Group in Nova Scotia) bevel a rugged paleokarst of Late Devonian – Early Mississippian age on the Port au Port Peninsula, western Newfoundland. Laminated limestones (Ship Cove Formation) and overlying evaporites (Codroy Road Formation) are similar to the sequence in the Bay St. George Subbasin, southwestern Newfoundland. In the Port au Port region, this sequence is laterally equivalent to biohermal limestones and plant-bearing siliciclastics of the proposed Big Cove Formation and red beds of the Lower Cove Formation. Lithostratigraphic correlation is supported by miospore and conodont biostratigraphies. Use of macrofaunal subzones is cautioned because there is evidence for the need to reevaluate the ranges of fossils that have previously been considered key indicators (e.g., Martinia galataea Bell) for parts of the Codroy and Windsor groups.The nature and lateral changes in Late Mississippian depositional environments and biofacies in the Port au Port region were the result of partial submergence of a complex predepositional topography and differential freshwater runoff (from the exposed Port au Port Ridge) creating fluctuating salinities and varying influx of siliciclastics. Limestone–evaporite sequences developed in broad, flat basins, carbonate buildups and siliciclastics accumulated in partially submerged paleokarst valleys adjacent to a rocky shoreline, and red beds formed part of the adjacent terrestrial landscape.

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Morphometric Study of Craters on Saturn’s Moon Rhea

The Planetary Science Journal ◽

10.3847/psj/ac32d4 ◽

2021 ◽

Vol 2 (6) ◽

pp. 235

Author(s):

Betzaida Aponte-Hernández ◽

Edgard G. Rivera-Valentín ◽

Michelle R. Kirchoff ◽

Paul M. Schenk

Keyword(s):

Surface Properties ◽

Crater Depth ◽

Morphometric Study ◽

Crater Wall ◽

Icy Moons ◽

Modification Process ◽

Post Impact ◽

Crater Morphology ◽

Impact Modification ◽

Wall Slope

Abstract Morphometric studies of impact craters on icy moons can be used to understand modification of crater topography. Several processes (e.g., viscous relaxation, ejecta deposition, repeated and overlapping impacts) act to shallow crater depth and relax the crater wall slope to similar or varying extents. Resolving these processes can help constrain the interior structure and surface properties of icy moons. Here, using morphometric measurements of craters on Rhea, we aim to constrain the processes that led to the observed crater population. We measured crater diameter, depth, and wall slope, as well as overall crater morphology (e.g., simple versus complex craters). Our results indicate that there exists a linear correlation between impact crater depth-to-diameter ratio and crater wall slope. This may suggest that the dominant modification process on Rhea is one that affects both properties simultaneously, which supports past heating events as the primary post-impact modification process. Additionally, the simple-to-complex crater transition for Rhea was found to be 12 ± 2 km, which is consistent with reported transition diameters for comparably sized icy bodies, indicating similar surface properties. A transition to shallower crater depths for large complex craters was not documented, indicating the absence of a rheological transition at depth in Rhea’s icy lithosphere, which may support the interpretation that Rhea is not fully differentiated.

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