scholarly journals Stratigraphy and fossil plants from the Cutler Formation (Late Paleozoic) and their paleoclimatic implications, eastern Paradox Basin, Colorado

2015 ◽  
Vol 2 ◽  
pp. 9-27
Author(s):  
Kendall R. Grazul ◽  
Jacqueline E. Huntoon ◽  
Jennifer M.K. O’Keefe
Keyword(s):  
Alluvial Fan ◽  
Late Paleozoic ◽  
Fossil Plants ◽  
Fossil Plant ◽  
Paradox Basin ◽  
Fine Grained ◽  
Plant Fossils ◽  
The North ◽  
Arid Conditions ◽  
Semi Arid

Exposures of the late Paleozoic Cutler Formation, near the town of Gateway, Colorado, have traditionally been interpreted as the product of alluvial-fan deposition along the western flank of the Uncompahgre uplift and within the easternmost portion of the Paradox Basin. The Paradox Basin formed between the western margin of the Uncompahgre uplift, a segment of the Ancestral Rocky Mountains, and the western paleoshoreline of the North American portion of Pangea. This part of Pangea is commonly thought to have experienced semi-arid to arid conditions and warm temperatures during the Pennsylvanian and Permian. We present stratigraphic and fossil plant evidence in this paper to support prior interpretations that the Cutler near Gateway, Colorado, was deposited by alluvial fans that hosted localized wetland areas. Our findings are consistent with the results of prior studies that have suggested the climate in the area was warm, semi-arid, and ice-free at the time the plants described in this paper were living. Plant fossils collected from the Cutler Formation came from two sites in The Palisade Wilderness Study Area (managed by the U.S. Department of the Interior, Bureau of Land Management) of western Colorado. The stratigraphic sections at the sites were composed mostly of pebble to cobble conglomerate and sandstone, but the fossil plants were mainly preserved in fine-grained intervals (fine-grained sandstone to siltstone). The preservation of plant fossils in the proximal Cutler Formation is remarkable because the surrounding sections consist mostly of conglomerate and sandstone interpreted as fluvial and debris-flow deposits. The fine-grained strata containing the plant horizons must have been deposited in a wet and protected setting, possibly a spring-fed abandoned channel on the alluvial fan. The plants and their surrounding sediment must have been rapidly buried in order to allow for long-term preservation of the fossils. It seems likely that vegetation was abundant in and adjacent to low-lying wet areas on the fan’s surface, based on the abundance of plant fossils found at the two sites. The fossil plant assemblage includes Calamites, Walchia, and Pecopteris. The flora are interpreted to have lived near the apex of the alluvial-fan system. These fossils suggest that warm and at least seasonally and locally wet conditions existed in the area during the time that the plants were growing. More arid conditions during the late Paleozoic are suggested by the characteristics of some of the time-equivalent and near time-equivalent rocks exposed to the west of the study area in the central Paradox Basin.

Stratigraphy and fossil plants from the Cutler Formation (Late Paleozoic) and their paleoclimatic implications, eastern Paradox Basin, Colorado

2015 ◽  
Vol 2 ◽  
pp. 9-27 ◽  
Author(s):  
Kendall Grazul ◽  
Jacqueline Huntoon ◽  
Jennifer O’Keefe
Keyword(s):  
Alluvial Fan ◽  
Late Paleozoic ◽  
Fossil Plants ◽  
Fossil Plant ◽  
Living Plant ◽  
Paradox Basin ◽  
Fine Grained ◽  
Plant Fossils ◽  
Arid Conditions ◽  
Semi Arid

Exposures of the late Paleozoic Cutler Formation, near the town of Gateway, Colorado, have traditionally been interpreted as the product of alluvial-fan deposition along the western flank of the Uncompahgre uplift and within the easternmost portion of the Paradox Basin. The Paradox Basin formed between the western margin of the Uncompahgre uplift, a segment of the Ancestral Rocky Mountains, and the western paleoshoreline of the North American portion of Pangea. This part of Pangea is commonly thought to have experienced semi-arid to arid conditions and warm temperatures during the Pennsylvanian and Permian. We present stratigraphic and fossil plant evidence in this paper to support prior interpretations that the Cutler near Gateway, Colorado, was deposited by alluvial fans that hosted localized wetland areas. Our findings are consistent with the results of prior studies that have suggested the climate in the area was warm, semi-arid, and ice-free at the time the plants described in this paper were living. Plant fossils collected from the Cutler Formation came from two sites in The Palisade Wilderness Study Area (managed by the U.S. Department of the Interior, Bureau of Land Management) of western Colorado. The stratigraphic sections at the sites were composed mostly of pebble to cobble conglomerate and sandstone, but the fossil plants were mainly preserved in fine-grained intervals (fine-grained sandstone to siltstone). The preservation of plant fossils in the proximal Cutler Formation is remarkable because the surrounding sections consist mostly of conglomerate and sandstone interpreted as fluvial and debris-flow deposits. The fine-grained strata containing the plant horizons must have been deposited in a wet and protected setting, possibly a spring-fed abandoned channel on the alluvial fan. The plants and their surrounding sediment must have been rapidly buried in order to allow for long-term preservation of the fossils. It seems likely that vegetation was abundant in and adjacent to low-lying wet areas on the fan’s surface, based on the abundance of plant fossils found at the two sites. The fossil plant assemblage includes Calamites, Walchia, and Pecopteris. The flora are interpreted to have lived near the apex of the alluvial-fan system. These fossils suggest that warm and at least seasonally and locally wet conditions existed in the area during the time that the plants were growing. More arid conditions during the late Paleozoic are suggested by the characteristics of some of the time-equivalent and near time-equivalent rocks exposed to the west of the study area in the central Paradox Basin.

scholarly journals Latest Cretaceous eggshell assemblage from the Willow Creek Formation (upper Maastrichtian – lower Paleocene) of Alberta, Canada, reveals higher dinosaur diversity than represented by skeletal remains

2017 ◽  
Vol 54 (2) ◽  
pp. 134-140 ◽  
Author(s):  
Darla K. Zelenitsky ◽  
François Therrien ◽  
Kohei Tanaka ◽  
Philip J. Currie ◽  
Christopher L. DeBuhr
Keyword(s):  
North American ◽  
Skeletal Remains ◽  
Taxonomic Affinity ◽  
The North ◽  
Arid Conditions ◽  
Fossil Bones ◽  
Semi Arid ◽  
Upper Maastrichtian

The Willow Creek Formation (upper Maastrichtian – lower Paleocene) of southwestern Alberta is a poorly fossiliferous formation that preserves a low end-Cretaceous dinosaur diversity compared with most correlative terrestrial deposits in the North American Western Interior. Although only three dinosaur taxa are known from skeletal remains (Tyrannosaurus rex, Hadrosauridae indet., and Leptoceratopsidae indet.), study of hundreds of dinosaur eggshells recovered from several sites in the formation reveals the presence of a more diverse dinosaur assemblage. Morphological and histological analyses of the eggshells indicate the presence of at least seven dinosaur ootaxa (Continuoolithus, Montanoolithus, Porituberoolithus, Prismatoolithus spp., Spheroolithus spp.). These ootaxa are referable to at least two ornithopod and five small theropod species, likely including dromaeosaurids, oviraptorosaurs, and troodontids. When considering the taxonomic affinity of eggshells and skeletal remains, the present study triples the known dinosaur diversity of the Willow Creek Formation, increasing the number of dinosaurs from three to at least nine species. Probable ornithopod eggshells comprise most of the eggshells preserved, although small theropods were likely an important component of the Willow Creek ecosystem, as most ootaxa can be ascribed to these dinosaurs. Although fossil bones are rarely found in the Willow Creek Formation, fossil eggshells are common compared with most other dinosaur-bearing formations in Alberta. The caliche-bearing deposits, indicative of arid to semi-arid conditions, typical of the formation were likely conducive to the preservation of calcareous eggshells.

XII.—On Salpingostoma dasu: A New Carboniferous Seed from East Lothian

1942 ◽  
Vol 60 (2) ◽  
pp. 427-464 ◽  
Author(s):  
W. T. Gordon
Keyword(s):  
Arid Climate ◽  
Fossil Plants ◽  
Lower Carboniferous ◽  
Positive Evidence ◽  
Arid Conditions ◽  
Lithological Character ◽  
Semi Arid

In a recent paper (Gordon, 1938) reasons were given for the belief that semi-arid conditions prevailed during Lower Carboniferous times in the neighbourhood of North Berwick, East Lothian. The evidence was opposed, in a measure, to that advanced by Mr George Barrow in the East Lothian Memoir (1910) to substantiate the same position. He had relied on the absence of fossils as part proof; but, in point of fact, fossil plants have been obtained in abundance from the actual bedded ashes of Oxroad Bay that he considered (a) to be unfossiliferous, and (b) to have been formed in a manner similar to beds on the Springbok Flats of the Transvaal. The plants that have now been obtained showed xerophytic features, and, consequently, a semi-arid climate was proved on positive evidence. Other positive evidence of a lithological character was also presented in confirmation (Gordon, 1938, pp. 352, 353).

XII.—On Salpingostoma dasu: A New Carboniferous Seed from East Lothian

1942 ◽  
Vol 50 (2) ◽  
pp. 427-464
Author(s):  
W. T. Gordon
Keyword(s):  
Arid Climate ◽  
Fossil Plants ◽  
Lower Carboniferous ◽  
Positive Evidence ◽  
Arid Conditions ◽  
Lithological Character ◽  
Semi Arid

In a recent paper (Gordon, 1938) reasons were given for the belief that semi-arid conditions prevailed during Lower Carboniferous times in the neighbourhood of North Berwick, East Lothian. The evidence was opposed, in a measure, to that advanced by Mr George Barrow in the East Lothian Memoir (1910) to substantiate the same position. He had relied on the absence of fossils as part proof; but, in point of fact, fossil plants have been obtained in abundance from the actual bedded ashes of Oxroad Bay that he considered (a) to be unfossiliferous, and (b) to have been formed in a manner similar to beds on the Springbok Flats of the Transvaal. The plants that have now been obtained showed xerophytic features, and, consequently, a semi-arid climate was proved on positive evidence. Other positive evidence of a lithological character was also presented in confirmation (Gordon, 1938, pp. 352, 353).

scholarly journals A Multidisciplinary Approach for Clarifying the Recharge Processes and Origin of Saline Water in the Semi-Arid Punata Alluvial fan in Bolivia

Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 946 ◽  
Author(s):  
Andres Gonzales Amaya ◽  
Gerhard Barmen ◽  
Galo Muñoz
Keyword(s):  
Stable Isotopes ◽  
Ion Exchange ◽  
Saline Water ◽  
Bottom Layer ◽  
Alluvial Fan ◽  
Aquifer System ◽  
Fine Grained ◽  
The North ◽  
Geophysical Surveys ◽  
Interpretation Process

The analysis of stable isotopes assisted in identifying that groundwater in the Punata alluvial fan is mainly recharged by heavy flash floods, and the recharge from rainfall is of less importance. In addition, the hydrochemical analysis identified the Pucara River as the main source of recharge. Other streams in the north and northwest of the fan do not seem to contribute to the recharge. The hydrochemistry also shows that there is an increase of the Na+ and Cl− concentrations in the middle and distal part of the fan. The salinization of groundwater is most likely a result of the mixing of fresh water with residual saline pore water in the lacustrine deposits and/or ion exchange within these layers. Geophysical surveys assisted in describing the aquifer system layering, and indicated a fine-grained bottom layer where ion exchange might occur. This study demonstrates that the integration of several methods (e.g., hydrochemistry, hydrogeophysics, and stable isotopes) is valuable for clarifying ambiguities during the interpretation process and for characterizing hydrogeological processes in alluvial fans in general.

scholarly journals Geology of the area between Bardibas and Sindhuli Madi, Sub-Himalaya, Central Nepal

2019 ◽  
Vol 58 ◽  
pp. 131-138 ◽  
Author(s):  
Amit Shrestha ◽  
Govind Joshi ◽  
Lalu Prasad Paudel ◽  
Soma Nath Sapkota ◽  
Rafael Almeida
Keyword(s):  
Coarse Grained ◽  
Calcareous Sand ◽  
Gangetic Plain ◽  
Fine Grained ◽  
Plant Fossils ◽  
The North ◽  
Central Nepal ◽  
Middle Siwalik ◽  
Siwalik Group ◽  
Salt And Pepper

The Siwalik Group (Sub-Himalaya) is the east-west extending youngest mountain belt formed by the sediments derived from the rising Himalaya on the north. The Siwalik Group is separated from the Lesser Himalaya to the north by the Main Boundary Thrust (MBT), and the Indo-Gangetic Plain to the south by the Main Frontal Thrust (MFT). The study was carried out mainly along the Ratu Nadi, Kamala Nadi river sections and was lithostratigraphically divided into the Lower Siwalik, Middle Siwalik, and Upper Siwalik, from the bottom to the top section, respectively. The Lower Siwalik is composed of fine-grained greenish grey calcareous sandstone (subarkose and lithic arenite), variegated mudstone, and calcareous siltstone. The Lower Siwalik is exposed due to the Marine Khola Thrust in the Gadyauli Khola, and sandstone there is more indurated and non-calcareous. The Middle Siwalik is mainly comprised of the medium- to coarse-grained salt-and-pepper sandstone (arkose and subarkose) with large cross lamination, calcareous sand lenses, convolute bedding, dark grey siltstone and mudstone. Plant fossils are also present in the finely laminated clay bed of the Middle Siwalik along the Ratu Nadi section. The Upper Siwalik comprises of mud- to sand-supported pebble to cobble conglomerates.  

scholarly journals Weltrichia magna sp. nov., a new record for the Middle Jurassic of Oaxaca, México

2021 ◽  
Vol 61 (1) ◽  
pp. 95-106
Author(s):  
Diana Silvia Guzmán-Madrid ◽  
María Patricia Velasco de León
Keyword(s):  
New Record ◽  
Fossil Plants ◽  
Reproductive Structure ◽  
Fine Grained ◽  
Reproductive Structures ◽  
The North ◽  
Mechanical Separation ◽  
Anatomical Characters ◽  
Pollen Sacs ◽  
San Juan Mixtepec

The Jurassic locality San Juan Mixtepec (Zorrillo Formation in the state of Oaxaca) contains fossil plants of the order Bennettitales, mainly of the genus Zamites, as well as reproductive structures of the genera Williamsonia, Williamsoniella and Weltrichia, but male reproductive structures of the latter genus are scarce and almost restricted to the south of Mexico; they have also been reported in the Triassic of the north of Mexico. Here we report a new record for this locality and a new species of male reproductive structure of the genus Weltrichia. We recovered half of an adpression in fine-grained sandstone with the positive and negative of the adaxial part of the male reproductive structure, which when open measures 22.6 cm in diameter. A reconstruction suggests the presence of ten centrifugal rays that become thinner towards the acute apex and are fused in a central basal cup. The structure exhibits complete centrifugal rays with basal structures that are interpreted as insertion sites for pollen sacs. We employed acetate peel, mechanical separation and hydrofluoric acid (HF) maceration techniques for extraction of anatomical samples. We compared 13 morphological and 10 anatomical characters with previous records from localities in México, Europe, Asia and other parts of the world. We observed epidermal cells and syndetocheilic stomatal apparatuses, which corroborate an epidermal affinity to the Bennettitales. This new record would be the largest male reproductive structure found in the region thus far, and increases the distribution of Weltrichia in the Jurassic of Oaxaca.

Deglacial Flood Origin of the Charleston Alluvial Fan, Lower Mississippi Alluvial Valley

1994 ◽  
Vol 41 (3) ◽  
pp. 278-284 ◽  
Author(s):  
Donna A. Porter ◽  
Margaret J. Guccione
Keyword(s):  
Mississippi River ◽  
Alluvial Fan ◽  
Coarse Grained ◽  
Silty Clay ◽  
Mississippi Valley ◽  
Lower Mississippi Valley ◽  
Fine Grained ◽  
The North ◽  
Sand Body ◽  
Braided Stream

AbstractLarge-magnitude flooding of the Mississippi River from proglacial lakes Agassiz and Superior most likely occurred between 11,300 and 10,900 and 9900 and 9500 yr B.P. The Charleston alluvial fan, a depositional remnant of one of these floods, is located at the head of a wide alluvial plain near Charleston, Missouri. The fan is an elongate, convex-up sand body (16 × 24 km) composed of medium- and fine-grained sand at least 8 m thick. This sand contrasts with the older coarse-grained sand of the braided stream surface to the west and south and younger silty clay of the meandering stream level to the north and east. A weakly developed soil separates the underlying braided steam deposits from the alluvial fan. A bulk-soil radiocarbon date of 10,590 ± 200 yr B.P. from the contact between the fan and clays of the meandering stream system indicates that the Charleston fan was deposited near the end of the early interval of flooding from Lake Agassiz about 10,900 yr B.P. If the Charleston fan is the last remnant of deglacial flooding in the lower Mississippi Valley, then deposition of significant quantities of sediment from largemagnitude floods between 10,000 and 9500 yr B.P. did not extend into the lower Mississippi Valley through Thebes Gap.

Sign in / Sign up

Export Citation Format

Share Document