SEDIMENTOLOGY AND CARBON ISOTOPE (δ13C) STRATIGRAPHY OF SILURIAN–DEVONIAN BOUNDARY INTERVAL STRATA, APPALACHIAN BASIN (PENNSYLVANIA, USA)

Palaios ◽  
2019 ◽  
Vol 34 (9) ◽  
pp. 405-423
Author(s):  
ANYA V. HESS ◽  
JEFFREY M. TROP
Keyword(s):  
New York ◽  
Carbon Isotope ◽  
Lower Devonian ◽  
Appalachian Basin ◽  
Sediment Supply ◽  
Fine Grained ◽  
Marine Strata ◽  
Central Pennsylvania ◽  
Storm Wave ◽  
Upper Silurian

ABSTRACT Silurian–Devonian boundary interval strata deposited during the expansion of land plants record a major perturbation of the carbon cycle, the global Klonk Event, one of the largest carbon isotope excursions during the Phanerozoic. In the Appalachian Basin, these marine strata record the regional buildup to the Acadian Orogeny. This study reports new sedimentologic, paleontologic, ichnologic, and carbon isotope data from an exceptional quarry exposure in central Pennsylvania, USA, a historically understudied area between better-documented outcrops >500 km away to the southwest (West Virginia, Virginia, Maryland) and northeast (New York). Facies spanning the continuous 113-m thick outcrop are dominantly carbonate and fine-grained siliciclastic strata interpreted as being deposited in supratidal through subtidal environments, including oxygen-limited environments below storm wave base. They record parts of three transgressive-regressive cycles, in the (1) upper Silurian Tonoloway Formation, (2) upper Silurian–Lower Devonian Keyser Formation through lower Mandata Member of the Old Port Formation, and (3) Lower Devonian Mandata through Ridgeley Members of the Old Port Formation. Micrite matrix δ13Ccarb analyses exhibit a large, positive δ13Ccarb excursion (>5‰ amplitude). Outcrops of this interval in the Appalachian Basin occur in two belts, between which correlation has been historically challenging. The regional correlation presented herein is based on carbon-isotope trends and is more consistent with published conodont biostratigraphy and volcanic ash ages, an improvement over published correlations based on lithostratigraphy. Transgressive-regressive trends at the central Pennsylvania study site are not consistent with regional trends, indicating that local controls (tectonics, sediment supply) rather than global (eustasy) dominated depositional patterns in the Silurian–Devonian boundary interval in the Appalachian Basin.

Vertebrate remains from Upper Silurian – Lower Devonian beds of Hall Land, North Greenland

1999 ◽  
pp. 1-80 ◽  
Author(s):  
Henning Blom
Keyword(s):  
Lower Devonian ◽  
Age Determination ◽  
Early Devonian ◽  
Marine Strata ◽  
South Of Siberia ◽  
Minor Part ◽  
Upper Silurian ◽  
A Minor ◽  
Devonian Age ◽  
North Greenland

NOTE: This monograph was published in a former series of GEUS Bulletin. Please use the original series name when citing this monograph, for example: Blom, H. (1999). Vertebrate remains from Upper Silurian – Lower Devonian beds of Hall Land, North Greenland. Geology of Greenland Survey Bulletin, 182, 1-80. https://doi.org/10.34194/ggub.v182.5126 _______________ Vertebrate microscopic remains of twenty-six taxa of thelodonts, heterostracans, osteostracans, anaspids, acanthodians and chondrichthyans are described from limestone beds in two localities of Late Silurian - Early Devonian age of the Chester Bjerg Formation, Hall Land, North Greenland. The limestone beds form a minor part of a monotonous calcareous sandstone-siltstone-mudstone sequence at the top of the Franklinian Basin succession.Stratigraphical recognition using several thelodont and acanthodian taxa, supported by regional geological and structural trends, suggests a Silurian-Devonian boundary interval between beds of the Halls Grav and Monument localities. This possible resolution of the previous problematic correlation between the two distant sections of monotonous nature demonstrates the potential biostratigraphic utility of thelodonts in Silurian -Devonian marine successions.The Chester Bjerg Formation thelodont assemblage is unique with several new endemic taxa, but Loganellia cf. L. tuvaensis is very similar to the type material of the Tuva region south of Siberia, Russia and indicates a Late Silurian age for the beds of the Halls Grav locality. Canonia cf. C. grossi suggests an Early Devonian age for the Monument locality, since Canonia is so far only found in Lower Devonian marine strata of Arctic Canada and Russia. Fragments of cosmopolitan acanthodian genera such as Poracanthodes, Gomphonchus and Nostolepis are found together with heterostracans, osteostracans, anaspids and chondrichthyans at both localities but do not give a more exact age determination than Late Silurian - Early Devonian. New thelodont taxa are Loganellia almgreeni sp. nov., Paralogania foliala sp. nov., Praetrilogania grabion gen. et sp. nov. and Thulolepis striaspina gen. et sp. nov. Nostolepis halli sp. nov. is a new acanthodian species.

Stromatoporoid Beds and Flat-Pebble Conglomerates Interpreted as Tsunami Deposits in the Upper Silurian of Podolia, Ukraine

2014 ◽  
Vol 64 (3) ◽  
pp. 261-280 ◽  
Author(s):  
Piotr Łuczyński ◽  
Stanisław skompski ◽  
Wojciech Kozłowski
Keyword(s):  
Large Scale ◽  
Energy Levels ◽  
High Energy ◽  
Tsunami Deposits ◽  
Growth Environment ◽  
Tsunami Waves ◽  
Fine Grained ◽  
Storm Wave ◽  
Very High Energy ◽  
Upper Silurian

Abstract Tsunami deposits are currently a subject of intensive studies. Tsunamis must have occurred in the geological past in the same frequency as nowadays, yet their identified depositional record is surprisingly scarce. Here we describe a hitherto unrecognized example of probable palaeotsunamites. The Upper Silurian (Pridoli) carbonate succession of Podolia (southwestern Ukraine) contains variously devel-oped event beds forming intercalations within peritidal deposits (shallow water limestones, nodular marls and dolomites). The event beds are represented by stromatoporoid and fine-grained bioclastic limestones, in some places accompanied by flat-pebble conglomerates. The interval with event beds can be traced along the Zbruch River in separate outcrops over a distance of more than 20 km along a transect oblique to the palaeoshoreline. The stro-matoporoid beds have erosional bottom surfaces and are composed of overturned and often fragmented massive skele-tons. The material has been transported landward from their offshore habitats and deposited in lagoonal settings. The flat-pebble conglomerates are composed of sub-angular micritic clasts that are lithologically identical to the sediments forming the underlying beds. Large-scale landward transport of the biogenic material has to be attributed to phenomena with very high energy levels, such as tropical hurricanes or tsunamis. This paper presents a tsunamigenic interpretation. Morphome-tric features of redeposited stromatoporoids point to a calm original growth environment at depths well below storm wave base. Tsunami waves are the most probable factor that could cause their redeposition from such a setting. The vastness of the area covered by parabiostromal stromatoporoid beds resembles the distribution of modern tsunami deposits in offshore settings. The stromatoporoid beds with unsorted stromatoporoids of various dimensions evenly distributed throughout the thickness of the beds and with clast-supported textures most probably represent deposition by traction. In some sections, the stromatoporoids are restricted to the lowermost parts of the beds, which pass upwards into bioclastic limestones. In this case, the finer material was deposited from suspension. The coexistence of stromatoporoid beds and flat-pebble conglomerates also allows presenting a tsunami interpretation of the latter. The propagating tsunami waves, led to erosion of partly lithified thin-layered mudstones, their fragmentation into flat clasts and redeposition as flat-pebble conglomerates.

The stromatoporoid Habrostroma in the upper Silurian (uppermost Pridoli)–Lower Devonian (Lochkovian) of North America, and the paleobiogeographic significance of H. centrotum (Girty, 1895)

2019 ◽  
Vol 94 (1) ◽  
pp. 11-27
Author(s):  
Carl W. Stock ◽  
Judith A. Burry-Stock
Keyword(s):  
New York ◽  
Cluster Analysis ◽  
North America ◽  
Lower Devonian ◽  
The Arctic ◽  
Water Filter ◽  
Hit Rate ◽  
Average Linkage ◽  
Morphological Variables ◽  
Upper Silurian

AbstractThree species of Habrostroma dominate stromatoporoid faunas in the Lower Devonian (Lochkovian) of five areas in North America: New York, Virginia, Maine, Bathurst Island, and Ellesmere Island. In addition, they occur in what could be the upper Silurian (uppermost Pridoli) of Virginia, and possibly New York. Measurements of nine morphologies from 127 specimens of Habrostroma were subjected to an average linkage cluster analysis. Using average linkage between groups, three distinct clusters were revealed. Group assignments made from the cluster analysis were saved, and entered into a canonical discriminant analysis with the nine morphological variables. An overall Wilks’ lambda was calculated, and is statistically significant at alpha <0.001. The hit rate for classifying group 1 is 98%, that for group 2 is 100%, and that for group 3 is 97.9%; the total hit rate is 100%. The morphological variables contributing most to group membership are: (1) percent cystlike microlaminae, (2) microlaminae per mm, (3) gallery height, (4) laminae per mm, and (5) laminar thickness. The statistics confirm that there are three species: H. centrotum, H. microporum, and H. consimile.Habrostroma centrotum occurs in all five areas. This is unusual because Virginia, New York, and Maine are part of the Eastern Americas Realm, and the arctic islands are part of the Old World Realm. Separation of the realms is based on a high percentage of unique genera in each. A breach in the inter-realm barrier is proposed to have existed across the Canadian Shield during the Lochkovian. The nature of the breach is determined to be a shallow-water filter, allowing the passage of a limited number of taxa.

The Somerset Island Formation: an upper Silurian to ?Lower Devonian intertidal/supratidal succession, Boothia Uplift region, Arctic Canada

1978 ◽  
Vol 15 (2) ◽  
pp. 181-189 ◽  
Author(s):  
A. D. Miall ◽  
J. Wm. Kerr ◽  
M. R. Gibling
Keyword(s):  
Lower Devonian ◽  
Alluvial Fan ◽  
Similar Sequence ◽  
Island Formation ◽  
Fine Grained ◽  
Rock Types ◽  
Sandstone Rock ◽  
Upper Silurian ◽  
Somerset Island ◽  
Cornwallis Island

The Somerset Island Formation of Somerset Island is a newly defined unit consisting of interbedded fine-grained, grey, planar-laminated dolomite and limestone, grey mottled limestone and dolomite, red quartzose siltstone and red dolosiltite. It forms a transitional unit between the limestone and dolomite of the underlying Read Bay Formation and the sandstone and conglomerate of the overlying Peel Sound Formation, and ranges in thickness from 150 to more than 400 m. The formation was formed predominantly in intertidal and supratidal environments and forms the lowest part of a regressive sequence that culminates in boulder conglomerates of alluvial fan origin in the Peel Sound Formation. The Somerset Island Formation is predominantly Pridolian in age, but may include some strata of Ludlovian and Gedinnian age.The regressive sequence reflects a major pulse of the Cornwallis Disturbance of Boothia Uplift. A similar sequence occurs in Prince of Wales Island, although the lower part of the succession there contains conglomerate and sandstone, rock types that are absent in Somerset Island. These rocks are formally assigned to the Lower Peel Sound Formation but are of similar age to the Somerset Island Formation of the type area.Rocks of similar facies to the Somerset Island Formation of Somerset Island comprise the upper member of the Drake Bay Formation on Russell Island and Member D of the Read Bay Formation on Cornwallis Island. The latter unit is younger than the Somerset Island Formation, reflecting a later commencement of regression in that area.

A subaerial arthropod trackway from the Upper Silurian Clam Bank Formation of Newfoundland

1995 ◽  
Vol 32 (3) ◽  
pp. 304-313 ◽  
Author(s):  
J. L. Wright ◽  
L. Quinn ◽  
D. E. G. Briggs ◽  
S. H. Williams
Keyword(s):  
Lower Devonian ◽  
Trace Fossil ◽  
Environment Analysis ◽  
Fine Grained ◽  
Body Drag ◽  
Upper Silurian ◽  
First Time ◽  
Parallel Series

Trackways are reported for the first time from Silurian rocks in Newfoundland. They occur in the Clam Bank Formation of the Port au Port Peninsula. At least one of the trackways represents one of the earliest known occurrences of a large subaerial arthropod trace fossil. It is preserved in hyporelief in a red fine-grained sandstone. The trackway, Diplichnites Dawson, 1873, consists of two parallel series of clearly defined imprints. It is attributed to a myriapod similar to the Lower Devonian Eoarthropleura. The sandstone contains halite pseudomorphs that indicate that the sediment horizon had been subject to desiccation immediately prior to the formation of the trackway. The arthropod walked on a red siltstone deposited in an alluvial flats environment. Analysis of the trackway suggests that the arthropod was approximately 23 cm long and had 17 pairs of walking appendages. It appears that a high-geared gait with a ratio of forestroke:backstroke of 8:2 was used in walking across the substrate, that is, approximately 20% of walking appendages were in contact with the substrate at any one time. This rapid gait, and the lack of a body drag mark, indicates that the arthropod was well adapted to subaerial locomotion. Knowledge of modern myriapod gaits has been used to extrapolate a theoretical trail, which compares well with the fossil trackway. Smaller, less well preserved trackways occur elsewhere in the Clam Bank Formation and may have been made by a similar arthropod.

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