scholarly journals A chronostratigraphic framework for the Upper Jurassic Morrison Formation, western U.S.A.

2019 ◽  
Vol 89 (10) ◽  
pp. 1017-1038 ◽  
Author(s):  
Susannah C.R. Maidment ◽  
Adrian Muxworthy
Keyword(s):  
Community Structure ◽  
Evolutionary Dynamics ◽  
Upper Jurassic ◽  
Radiometric Dating ◽  
Morrison Formation ◽  
Tectonic Control ◽  
Lacustrine Deposits ◽  
The North ◽  
Fluvial Architecture

ABSTRACT The fluvial, overbank, and lacustrine deposits of the Upper Jurassic Morrison Formation of the Western Interior, U.S.A. have been intensively studied due to their diverse and well-preserved dinosaurian fauna, and the presence of economic quantities of uranium and vanadium ores. The formation crops out over 12 degrees of latitude and 1.2 million km2, and is an excellent case study for the examination of paleoecology, community structure, and evolutionary dynamics at a time in Earth's history when the climate was significantly warmer than today. However, paleoecological studies have been hampered by lack of correlation across the formation. Assuming a primarily tectonic control on fluvial architecture, we propose the first chronostratigraphic framework of the formation, which is based on sequence stratigraphy, magnetostratigraphy, and radiometric dating. The formation can be divided into three sequences each represented by a period of degradation followed by aggradation. This chronostratigraphic framework indicates that the formation youngs to the north, and was deposited over about 7 million years during the late Kimmeridgian and Tithonian. This framework provides a foundation for future sedimentological, stratigraphic, and paleobiological studies of the iconic dinosaurian fauna known from the Morrison.

scholarly journals The Upper Jurassic Morrison Formation in north-central New Mexico–Linking Colorado Plateau stratigraphy to the stratigraphy of the High Plains

2018 ◽  
Vol 5 ◽  
pp. 117-129 ◽  
Author(s):  
Spencer Lucas
Keyword(s):  
New Mexico ◽  
Colorado Plateau ◽  
Far East ◽  
River System ◽  
Upper Jurassic ◽  
High Plains ◽  
Morrison Formation ◽  
Southern High Plains ◽  
North Central ◽  
The North

Most study of the Upper Jurassic Morrison Formation has focused on its spectacular and extensive outcrops on the southern Colorado Plateau. Nevertheless, outcrops of the Morrison Formation extend far off the Colorado Plateau, onto the southern High Plains as far east as western Oklahoma. Outcrops of the Morrison Formation east of and along the eastern flank of the Rio Grande rift in north-central New Mexico (Sandoval, Bernalillo, and San­ta Fe Counties) are geographically intermediate between the Morrison Formation outcrops on the southeastern Colorado Plateau in northwestern New Mexico and on the southern High Plains of eastern New Mexico. Previous lithostratigraphic correlations between the Colorado Plateau and High Plains Morrison Formation outcrops using the north-central New Mexico sections encompassed a geographic gap in outcrop data of about 100 km. New data on previously unstudied Morrison Formation outcrops at Placitas in Sandoval County and south of Lamy in Santa Fe County reduce that gap and significantly add to stratigraphic coverage. At Placitas, the Morrison Formation is about 141 m thick, in the Lamy area it is about 232 m thick, and, at both locations, it consists of the (ascending) sandstone-dominated Salt Wash Member, mudstone-dominated Brushy Basin Member, and sandstone-dominat­ed Jackpile Member. Correlation of Morrison strata across northern New Mexico documents the continuity of the Morrison depositional systems from the Colorado Plateau eastward onto the southern High Plains. Along this transect, there is significant stratigraphic relief on the base of the Salt Wash Member (J-5 unconformity), the base of the Jackpile Member, and the base of the Cretaceous strata that overlie the Morrison Formation (K unconfor­mity). Salt Wash Member deposition was generally by easterly-flowing rivers, and this river system continued well east of the Colorado Plateau. The continuity of the Brushy Basin Member, and its characteristic zeolite-rich clay facies, onto the High Plains suggests that localized depositional models (e.g., “Lake T’oo’dichi’) need to be re-eval­uated. Instead, envisioning Brushy Basin Member deposition on a vast muddy floodplain, with some localized lacustrine and palustrine depocenters, better interprets its distribution and facies.

scholarly journals Decomposition of dinosaurian remains inferred by invertebrate traces on vertebrate bone reveal new insights into Late Jurassic ecology, decay, and climate in western Colorado

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9510
Author(s):  
Julia B. McHugh ◽  
Stephanie K. Drumheller ◽  
Anja Riedel ◽  
Miriam Kane
Keyword(s):  
Late Jurassic ◽  
Upper Jurassic ◽  
Site Formation ◽  
Morrison Formation ◽  
Bone Surface ◽  
The North ◽  
Western Colorado ◽  
Burial Rates ◽  
Minimum Residence Time ◽  
Taphonomic Analysis

A survey of 2,368 vertebrate fossils from the Upper Jurassic Mygatt-Moore Quarry (MMQ) (Morrison Formation, Brushy Basin Member) in western Colorado revealed 2,161 bone surface modifications on 884 specimens. This is the largest, site-wide bone surface modification survey of any Jurassic locality. Traces made by invertebrate actors were common in the assemblage, second in observed frequency after vertebrate bite marks. Invertebrate traces are found on 16.174% of the total surveyed material and comprise 20.148% of all identified traces. Six distinct invertebrate trace types were identified, including pits and furrows, rosettes, two types of bioglyph scrapes, bore holes and chambers. A minimum of four trace makers are indicated by the types, sizes and morphologies of the traces. Potential trace makers are inferred to be dermestid or clerid beetles, gastropods, an unknown necrophagous insect, and an unknown osteophagus insect. Of these, only gastropods are preserved at the site as body fossils. The remaining potential trace makers are part of the hidden paleodiversity from the North American Late Jurassic Period, revealed only through this ichnologic and taphonomic analysis. Site taphonomy suggests variable, but generally slow burial rates that range from months up to 6 years, while invertebrate traces on exposed elements indicate a minimum residence time of five months for carcasses with even few preserved invertebrate traces. These traces provide insight into the paleoecology, paleoclimate, and site formation of the MMQ, especially with regards to residence times of the skeletal remains on the paleolandscape. Comprehensive taphonomic studies, like this survey, are useful in exploring patterns of paleoecology and site formation, but they are also rare in Mesozoic assemblages. Additional work is required to determine if 16.174% is typical of bulk-collected fossils from Jurassic ecosystems in North America, or if the MMQ represents an unusual locality.

scholarly journals The Morrison Formation and its bounding strata on the western side of the Blanding basin, San Juan County, Utah

2020 ◽  
Vol 7 ◽  
pp. 137-195
Author(s):  
James Kirkland ◽  
Donald DeBlieux ◽  
ReBecca Hunt-Foster ◽  
John Foster ◽  
Kelli Trujillo ◽  
...  
Keyword(s):  
Upper Jurassic ◽  
Climatic Conditions ◽  
Morrison Formation ◽  
National Monument ◽  
The North ◽  
Type Area ◽  
Fossil Vertebrate ◽  
Western Side ◽  
San Juan County ◽  
San Rafael

In 2016 and 2017, the Utah Geological Survey partnered with the U.S. Bureau of Land Management to conduct a paleontological inventory of the Morrison Formation south and west of Blanding, Utah, along the eastern margin of the Bears Ears National Monument. The Morrison in this region is critical to understanding Upper Jurassic stratigraphy across the Colorado Plateau because it is the type area for the Bluff Sandstone, Recapture, Westwater Canyon, and Brushy Basin Members of the Morrison Formation, which are the basis for nomenclature in New Mexico and Arizona as well. Researchers have disagreed about nomenclature and correlation of these units, which transition northward in the study area into the Tidwell, Salt Wash, and Brushy Basin Members. Numerous vertebrate localities make inclusion of the Bluff Sandstone and Recapture Members in the Middle Jurassic San Rafael Group, as suggested by some previous workers, unlikely. The Salt Wash Member does not separate the Bluff Sandstone and Recapture Members at Recapture Wash, but sandstone lenses of Salt Wash facies occur higher in northern Recapture exposures. Northward, along the outcrop belt east of Comb Ridge, the Bluff-Recapture interval thins, interlenses, and pinches out into the Tidwell and lower Salt Wash, with the main lower sandstone interval of the Westwater Canyon merging northward into the upper Salt Wash Member. The partly covered, 1938 type section of the Brushy Basin Member is identified along Elk Mountain Road at the southern end of Brushy Basin. We describe a detailed, accessible Morrison Formation reference section about 11.2 km (7 mi) to the south along Butler Wash. There, 81.68 m (268 ft) of Brushy Basin Member is well exposed along a road between the top of the Westwater Canyon Member and the base of the Lower Cretaceous Burro Canyon Formation. We informally call the upper sandstone bed(s) of the Westwater Canyon Member that cap mesas and benches in the region “No-Mans Island beds.” Smectitic mudstones between the No-Mans Island beds and the main sandstone body of the Westwater Canyon suggest that the Salt Wash-Brushy Basin contact to the north may be somewhat older than the base of the Brushy Basin Member as originally defined in its type area. Determining whether the No-Mans Island beds pinch out to the north or are removed by erosion below the regional basal Brushy Basin paleosol requires further research. Several significant fossil vertebrate and plant sites have been documented in the Brushy Basin type area. Newly identified volcanic ashes provided zircons for U-Pb ages of 150.67 ± 0.32 Ma from near the top of the Brushy Basin Member and of 153.7 ± 2.1 Ma and 153.8 ± 2.2 Ma for two zircons in lower part of Recapture Member. At the top of the Brushy Basin Member, ferruginous paleosols commonly overlying conglomeratic sandstone are speculated to be of Early Cretaceous age (detrital zircon age pending) and are assigned herein to the Yellow Cat Member of the Burro Canyon Formation. These iron-rich paleosols suggest wetter climatic conditions during the Jurassic-Cretaceous transition in the Blanding basin.

scholarly journals The Upper Jurassic Morrison Formation in north-central New Mexico–Linking Colorado Plateau stratigraphy to the stratigraphy of the High Plains

2018 ◽  
Vol 5 ◽  
pp. 117-129
Author(s):  
Spencer G Lucas
Keyword(s):  
New Mexico ◽  
Colorado Plateau ◽  
Far East ◽  
River System ◽  
Upper Jurassic ◽  
High Plains ◽  
Morrison Formation ◽  
Southern High Plains ◽  
North Central ◽  
The North

Most study of the Upper Jurassic Morrison Formation has focused on its spectacular and extensive outcrops on the southern Colorado Plateau. Nevertheless, outcrops of the Morrison Formation extend far off the Colorado Plateau, onto the southern High Plains as far east as western Oklahoma. Outcrops of the Morrison Formation east of and along the eastern flank of the Rio Grande rift in north-central New Mexico (Sandoval, Bernalillo, and San­ta Fe Counties) are geographically intermediate between the Morrison Formation outcrops on the southeastern Colorado Plateau in northwestern New Mexico and on the southern High Plains of eastern New Mexico. Previous lithostratigraphic correlations between the Colorado Plateau and High Plains Morrison Formation outcrops using the north-central New Mexico sections encompassed a geographic gap in outcrop data of about 100 km. New data on previously unstudied Morrison Formation outcrops at Placitas in Sandoval County and south of Lamy in Santa Fe County reduce that gap and significantly add to stratigraphic coverage. At Placitas, the Morrison Formation is about 141 m thick, in the Lamy area it is about 232 m thick, and, at both locations, it consists of the (ascending) sandstone-dominated Salt Wash Member, mudstone-dominated Brushy Basin Member, and sandstone-dominat­ed Jackpile Member. Correlation of Morrison strata across northern New Mexico documents the continuity of the Morrison depositional systems from the Colorado Plateau eastward onto the southern High Plains. Along this transect, there is significant stratigraphic relief on the base of the Salt Wash Member (J-5 unconformity), the base of the Jackpile Member, and the base of the Cretaceous strata that overlie the Morrison Formation (K unconfor­mity). Salt Wash Member deposition was generally by easterly-flowing rivers, and this river system continued well east of the Colorado Plateau. The continuity of the Brushy Basin Member, and its characteristic zeolite-rich clay facies, onto the High Plains suggests that localized depositional models (e.g., “Lake T’oo’dichi’) need to be re-eval­uated. Instead, envisioning Brushy Basin Member deposition on a vast muddy floodplain, with some localized lacustrine and palustrine depocenters, better interprets its distribution and facies.

Sport and nationalism in the Republic of North Macedonia

Focaal ◽  
2019 ◽  
pp. 1-13
Author(s):  
Vasiliki P. Neofotistos
Keyword(s):  
Direct Product ◽  
Nation Building ◽  
National History ◽  
Sports Teams ◽  
The Balkans ◽  
The North ◽  
Political Forces ◽  
The Republic

Using the Republic of North Macedonia as a case study, this article analyzes the processes through which national sports teams’ losing performance acquires a broad social and political significance. I explore claims to sporting victory as a direct product of political forces in countries located at the bottom of the global hierarchy that participate in a wider system of coercive rule, frequently referred to as empire. I also analyze how public celebrations of claimed sporting victories are intertwined with nation-building efforts, especially toward the global legitimization of a particular version of national history and heritage. The North Macedonia case provides a fruitful lens through which we can better understand unfolding sociopolitical developments, whereby imaginings of the global interlock with local interests and needs, in the Balkans and beyond.

The transformative power of European technology in resource exploitation: reflections on the oil presses and railways of colonial Nigeria

2020 ◽  
Vol 13 (3) ◽  
pp. 555-582
Author(s):  
Nkemjika Chimee
Keyword(s):  
Technological Innovations ◽  
Resource Exploitation ◽  
Transformative Power ◽  
The North ◽  
Indigenous Production ◽  
Impact Of Technology ◽  
Transformative Impact ◽  
North And South ◽  
European Technology

Technological innovations, which in the nineteenth century were principally developed by European nations, were a crucial factor in transforming economies – not only those of the countries in which they originated, but also those of their colonies. This case study of Nigeria explores the way the British controlled the colony and subjugated the local people as a result of their superior technology. Upon taking over the territory, to aid the country's economic development, they began to construct railway lines to link major resource zones of the north and south. This facilitated the more efficient shipment of natural resources from these zones to the coastal ports for onward shipment to Britain. Indigenous production and the rendering of palm oil were transformed by the introduction of oil presses. The article examines the transformative impact of technology in resource exploitation, focusing specifically on railways and oil presses and their impact on Nigerian society.

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