scholarly journals Conodont biostratigraphy and depositional history of the Darriwilian (Middle Ordovician) Pygodus serra Zone, western Argentina

2019 ◽  
Vol 46 (2) ◽  
pp. 336
Author(s):  
Susana Heredia ◽  
Ana Mestre ◽  
Cintia Kaufmann ◽  
Tatiana Soria
Keyword(s):  
Variable Amount ◽  
Depositional History ◽  
Middle Ordovician ◽  
Clastic Rocks ◽  
Stratigraphic Record ◽  
Conodont Zone ◽  
History Of ◽  
San Rafael ◽  
Clastic Sedimentary ◽  
Almost All

The stratigraphic record of the Pygodus serra conodont Zone in the Cuyania terrane of western Argentina is discussed in this contribution. Three well-known sections were sampled in Precordillera and the San Rafael Block. The studied successions are composed mainly by clastic rocks with variable amount of carbonate. The lower part of Ponón Trehué Formation of the San Rafael Block and the La Cantera Formation of the Eastern Precordillera are composed of conglomerate and represent the input of coarse clastic deposits to the Cuyania basin. The Los Azules Formation, in Los Amarillitos section of the Central Precordillera, has a massive sandstone bed with carbonate nodules in a section largely of black shale. Key conodonts recovered from these sections indicate a correlation to the E. robustus and E. lindstroemi subzones of the Pygodus serra Zone of the upper Darriwillian Stage (Middle Ordovician Series). The species in the Ponón Trehué Formation are almost all the same as those in the Precordillera sections. Correlation of the clastic sedimentary successions between the three sections indicates that vertical facies changes were not controlled by eustasy. More likely, they were controlled by differential tectonic subsidence.

The tectonics and depositional history of the Ordovician and Silurian rocks of Notre Dame Bay, Newfoundland

1985 ◽  
Vol 22 (4) ◽  
pp. 607-618 ◽  
Author(s):  
R. J. Arnott ◽  
W. S. McKerrow ◽  
L. R. M. Cocks
Keyword(s):  
Strike Slip ◽  
Late Ordovician ◽  
Island Arc ◽  
The West ◽  
Depositional History ◽  
Middle Ordovician ◽  
The North ◽  
Lower Ordovician ◽  
History Of ◽  
Ophiolitic Rocks

In the Notre Dame Bay region, ophiolitic rocks underlie a thick sequence of Lower Ordovician volcanic-arc rocks to the north of the Lobster Cove – Chanceport Fault. Neither this fault nor the Lukes Arm – Sops Head Fault shows evidence of very large strike-slip movements, as parts of the same arc, together with much arc-derived detritus, straddle both faults. Towards the east, this arc-derived detritus becomes more distal in aspect and passes laterally into the Dunnage Mélange. During the Middle Ordovician Epoch (late Llandeilo and early Caradoc), most areas show a marked decrease in volcanic activity and in the amount of coarse detritus deposited. Coarse turbidites reappear, at different times in different areas, during the Late Ordovician. These are related to several fault-bounded basins and to movements on the Lukes Arm – Sops Head Fault. Many of these faults, particularly in the east, are marked by olistostromes, several of which can be dated by fossils as Late Ordovician and Early Silurian. The whole region, between the Reach Fault on the east and the Baie Verte – Brompton Line on the west, has a stratigraphic unity. If it has been moved by strike slip relative to the Long Range, then any such fault must lie to the west of the Baie Verte – Brompton Line. The interpretation of an Early Ordovician island arc moving above an easterly directed subduction zone is in accord with both the geochemical and palaeontological evidence. The Notre Dame Bay region may have been converted into a transform-dominated margin in the Late Ordovician and Early Silurian in a manner analogous to the oblique slip tectonic regimes of the Californian and New Zealand margins during the Tertiary, with a precursor of the Reach Fault marking the edge of the continent after the Notre Dame island arc had collided with North America.

Depositional Environments and Conodont-Based Correlation of the Long Point Formation (Middle Ordovician), Western Newfoundland

1973 ◽  
Vol 10 (12) ◽  
pp. 1822-1833 ◽  
Author(s):  
Lars E. Fåhræus
Keyword(s):  
Depositional Environments ◽  
Total Thickness ◽  
Depositional History ◽  
British Standard ◽  
Fringing Reef ◽  
Middle Ordovician ◽  
History Of ◽  
Carbonate Bank

The depositional history of the neoautochthonous mid-Caradocian Long Point Formation, which overlies the lower clastic slices of the Humber Arm Klippe, is characterized by two major periods of sedimentation. Out of a total thickness of some 600 m, slightly less than 60 m make up a lower sequence of limestone, minor shales, and a basal sandstone unit, which appears to have been deposited in an environment (or series of environments) characterized by beachsands, mudflats, lagoons, (?) carbonate bank, and a fringing reef. The remainder of the Long Point deposits exhibit several criteria that are suggestive of the general environment of a prograding fluviomarine delta. It appears possible that uppermost Long Point strata are fluviatile in origin.In terms of graptolite and conodont zonations, the Long Point Formation belongs within the Diplograptus multidens and Amorphognathus tvaerensis Zones, respectively. The base of the Long Point Formation probably coincides with the base of the Climacograptus peltifer Zone of the British standard graptolite zonation and with that of the Prioniodus gerdae conodont subzone.

From the Tower of London to the Thomas More Society of Buenos Aires: “Give me thy grace, good Lord, to set the world at nought”

Moreana ◽  
2005 ◽  
Vol 42 (Number 164) (4) ◽  
pp. 187-206
Author(s):  
Clare M. Murphy
Keyword(s):  
Buenos Aires ◽  
Short History ◽  
Thomas More ◽  
Tower Of London ◽  
Hebrew Poetry ◽  
Prayer Book ◽  
The World ◽  
History Of ◽  
Book Of Hours ◽  
Almost All

The Thomas More Society of Buenos Aires begins or ends almost all its events by reciting in both English and Spanish a prayer written by More in the margins of his Book of Hours probably while he was a prisoner in the Tower of London. After a short history of what is called Thomas More’s Prayer Book, the author studies the prayer as a poem written in the form of a psalm according to the structure of Hebrew poetry, and looks at the poem’s content as a psalm of lament.

Tracking dinosaurs in BLM canyon country, Utah

2018 ◽  
Vol 3 ◽  
pp. 67-100 ◽  
Author(s):  
ReBecca K. Hunt-Foster ◽  
Martin G. Lockley ◽  
Andrew R.C. Milner ◽  
John R. Foster ◽  
Neffra A. Matthews ◽  
...  
Keyword(s):  
Colorado Plateau ◽  
Foreland Basin ◽  
Salt Tectonics ◽  
Initial Development ◽  
Paradox Basin ◽  
Cedar Mountain Formation ◽  
History Of ◽  
San Rafael ◽  
San Rafael Swell ◽  
Biological History

Although only recognized as a discrete stratigraphic unit since 1944, the Cedar Mountain Formation represents tens of millions of years of geological and biological history on the central Colorado Plateau. This field guide represents an attempt to pull together the results of recent research on the lithostratigraphy, chronostratigraphy, sequence stratigraphy, chemostratigraphy, and biostratigraphy of these medial Mesozoic strata that document the dynamic and complex geological history of this region. Additionally, these data provide a framework by which to examine the history of terrestrial faunas during the final breakup of Pangaea. In fact, the medial Mesozoic faunal record of eastern Utah should be considered a keystone in understanding the history of life across the northern hemisphere. Following a period of erosion and sediment bypass spanning the Jurassic–Cretaceous boundary, sedimentation across the quiescent Colorado Plateau began during the Early Cretaceous. Thickening of these basal Cretaceous strata across the northern Paradox Basin indicate that salt tectonics may have been the predominant control on deposition in this region leading to the local preservation of fossiliferous strata, while sediment bypass continued elsewhere. Thickening of overlying Aptian strata west across the San Rafael Swell provides direct evidence of the earliest development of a foreland basin with Sevier thrusting that postdates geochemical evidence for the initial development of a rain shadow.

Tracking dinosaurs in BLM canyon country, Utah

2016 ◽  
Vol 3 ◽  
pp. 67-100
Author(s):  
ReBecca Hunt-Foster ◽  
Martin Lockley ◽  
Andrew Milner ◽  
John Foster ◽  
Neffra Matthews ◽  
...  
Keyword(s):  
Colorado Plateau ◽  
Foreland Basin ◽  
Salt Tectonics ◽  
Initial Development ◽  
Paradox Basin ◽  
Cedar Mountain Formation ◽  
History Of ◽  
San Rafael ◽  
San Rafael Swell ◽  
Biological History

Although only recognized as a discrete stratigraphic unit since 1944, the Cedar Mountain Formation represents tens of millions of years of geological and biological history on the central Colorado Plateau. This field guide represents an attempt to pull together the results of recent research on the lithostratigraphy, chronostratigraphy, sequence stratigraphy, chemostratigraphy, and biostratigraphy of these medial Mesozoic strata that document the dynamic and complex geological history of this region. Additionally, these data provide a framework by which to examine the history of terrestrial faunas during the final breakup of Pangaea. In fact, the medial Mesozoic faunal record of eastern Utah should be considered a keystone in understanding the history of life across the northern hemisphere. Following a period of erosion and sediment bypass spanning the Jurassic–Cretaceous boundary, sedimentation across the quiescent Colorado Plateau began during the Early Cretaceous. Thickening of these basal Cretaceous strata across the northern Paradox Basin indicate that salt tectonics may have been the predominant control on deposition in this region leading to the local preservation of fossiliferous strata, while sediment bypass continued elsewhere. Thickening of overlying Aptian strata west across the San Rafael Swell provides direct evidence of the earliest development of a foreland basin with Sevier thrusting that postdates geochemical evidence for the initial development of a rain shadow.

The Lower Cretaceous in east-central Utah—The Cedar Mountain Formation and its bounding strata

2016 ◽  
Vol 3 ◽  
pp. 101-228 ◽  
Author(s):  
James Kirkland ◽  
Marina Suarez ◽  
Celina Suarez ◽  
ReBecca Hunt-Foster
Keyword(s):  
Colorado Plateau ◽  
Foreland Basin ◽  
Salt Tectonics ◽  
Initial Development ◽  
Paradox Basin ◽  
Cedar Mountain Formation ◽  
History Of ◽  
San Rafael ◽  
San Rafael Swell ◽  
Biological History

Although only recognized as a discrete stratigraphic unit since 1944, the Cedar Mountain Formation represents tens of millions of years of geological and biological history on the central Colorado Plateau. This field guide represents an attempt to pull together the results of recent research on the lithostratigraphy, chronostratigraphy, sequence stratigraphy, chemostratigraphy, and biostratigraphy of these medial Mesozoic strata that document the dynamic and complex geological history of this region. Additionally, these data provide a framework by which to examine the history of terrestrial faunas during the final breakup of Pangaea. In fact, the medial Mesozoic faunal record of eastern Utah should be considered a keystone in understanding the history of life across the northern hemisphere. Following a period of erosion and sediment bypass spanning the Jurassic–Cretaceous boundary, sedimentation across the quiescent Colorado Plateau began during the Early Cretaceous. Thickening of these basal Cretaceous strata across the northern Paradox Basin indicate that salt tectonics may have been the predominant control on deposition in this region leading to the local preservation of fossiliferous strata, while sediment bypass continued elsewhere. Thickening of overlying Aptian strata west across the San Rafael Swell provides direct evidence of the earliest development of a foreland basin with Sevier thrusting that postdates geochemical evidence for the initial development of a rain shadow.

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