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James E. Fassett

Publications and source records attributed to James E. Fassett.

18 recordsLinked to original sources
USGS2002

Dinosaurs that did not die: Evidence for Paleocene dinosaurs in the Ojo Alamo Sandstone, San Juan Basin, New Mexico

Palynologic and paleomagnetic data confirm a Paleocene age for the Ojo Alamo Sandstone (and its contained dinosaurs) throughout the San Juan Basin of New Mexico. The recently reported discovery of 34 skeletal elements from a single hadrosaur in the Ojo Alamo provides unequivocal evidence that these bones were not reworked from underlying Cretaceous strata. Geochemical studies of samples from several single-dinosaur-bone specimens from the Paleocene Ojo Alamo Sandstone and the underlying Late Cretaceous (Campanian) Kirtland Formation show that mineralized bones from these two rock units contain distinctly different abundances of uranium and rare-earth elements and demonstrate that Cretaceous and Paleocene bones were mineralized at different times when mineralizing fluids had distinctly different chemical compositions. These findings indicate that the dinosaur bone from the Paleocene Ojo Alamo is indigenous and not reworked. These data show that a relatively diverse assemblage of dinosaurs survived the end-Cretaceous asteroid-impact extinction event of 65.5 Ma. The San Juan Basin’s Paleocene dinosaur fauna is herein named the Alamoan fauna. Magnetic-polarity chronology shows that these survivors lived for about one million years into the Paleocene and then became extinct around 64.5 Ma. We suggest that a plausible survival mechanism for this Lazarus fauna may have been the large numbers of buried dinosaur eggs, laid just before the asteroid impact occurred. These buried eggs would have provided a safe haven for developing dinosaur embryos for the first one to two years after the impact, thereby making it possible for them to survive the worst of the impact’s early devastation.

Colorado, New Mexico↗
USGS2000

Evidence for Paleocene dinosaurs in the Ojo Alamo Sandstone, San Juan Basin, New Mexico

Dinosaur fossils from the Ojo Alamo Sandstone, San Juan Basin, New Mexico, have been a puzzle to geologists for decades because other stratigraphic and paleontologic evidence indicates that this formation is Paleocene in age. The Paleocene age of the Ojo Alamo is based on the following evidence: (1) the lowermost part of the Nacimiento Formation, which conformably overlies and intertongues with the Ojo Alamo Sandstone in the Ojo Alamo type area in the southern part of the basin, contains Paleocene (Puercan) mammalian fossils; (2) plant megafossils collected from the Ojo Alamo indicate a Tertiary age for this rock unit; (3) pollen-productive rock samples collected from the Ojo Alamo at several localities in the basin have, without exception, yielded Paleocene-age palynomorph assemblages, and conversely, no Cretaceous pollen has ever been reported from Ojo Alamo rock samples. We report here the first discovery of Paleocene palynomorphs from Ojo Alamo Sandstone outcrops in the northern San Juan Basin. The pollen-producing rock samples were collected from a coaly, carbonaceous shale bed 12-m above the base of the Ojo Alamo and 3-m below the level of a large hadrosaur femur (1310-mm long and weighing about 130 kg) collected from this site. The bone was recovered from a cobble-to-boulder conglomeratic sandstone but shows no evidence of abrasion by erosion indicating almost instant burial after death of the animal and early mineralization of the femur. It is our opinion that this bone was not reworked from underlying Cretaceous strata. The data from the San Juan River site indicate that dinosaurs did not die out at the end of the Cretaceous in the San Juan Basin, but lived on for as much as a few hundred thousand years into the Paleocene before finally becoming extinct.

New Mexico↗
USGS1997

Geology and structure of the Pine River, Florida River, Carbon Junction, and Basin Creek gas seeps, La Plata County, Colorado

Introduction: This study was commissioned by a consortium consisting of the Bureau of Land Management, Durango Office; the Colorado Oil and Gas Conservation Commission; La Plata County; and all of the major gas-producing companies operating in La Plata County, Colorado. The gas-seep study project consisted of four parts; 1) detailed surface mapping of Fruitland Formation coal outcrops in the above listed seep areas, 2) detailed measurement of joint and fracture patterns in the seep areas, 3) detailed coal-bed correlation of Fruitland coals in the subsurface adjacent to the seep areas, and 4) studies of deep-seated seismic patterns in those seep areas where seismic data was available. This report is divided into three chapters labeled 1, 2, and 3. Chapter 1 contains the results of the subsurface coal-bed correla-tion study, chapter 2 contains the results of the surface geologic mapping and joint measurement study, and chapter 3, contains the results of the deep-seismic study. A preliminary draft of this report was submitted to the La Plata County Group in September 1996. All of the members of the La Plata Group were given an opportunity to critically review the draft report and their comments were the basis for revising the first draft to create this final version of a geologic report on the major La Plata County gas seeps located north of the Southern Ute Indian Reservation.

Open-File Report↗
USGS1997

Precise age of C33N-C32R magnetic-polarity reversal, San Juan Basin, New Mexico and Colorado

Polarity-chron boundary C33n-C32r has been identified in the Upper Cretaceous continental Farmington Sandstone Member of the Kirtland Shale in Hunter Wash in the southwest part of the San Juan Basin of New Mexico, and in the marine Lewis Shale at Chimney Rock, Colorado, in the northeast part of the basin. Single- and multiple-crystal laser fusion 40 Ar/ 39 Ar ages of sanidine crystals from volcanic ash beds bracketing the C33n-C32r polarity reversal at Hunter Wash establish its age as 73.50 ± 0.18 Ma. The reversal apparently occurs within the Baculites compressus Western Interior ammonite zone and within the Edmontonian land-vertebrate faunal zone. An 8 Ma hiatus separates Cretaceous and Tertiary rocks in the southern San Juan Basin. These findings provide a precise new interpolated Late Cretaceous tie point for geologic time scales, provide the basis for the direct correlation of Western Interior ammonite zones to European open-ocean faunal zones, and establish the first direct tie between continental and marine fossil zones within the Western Interior of North America.

Colorado;New Mexico↗
USGS1994

Report on drilling activities in the Thar Desert, Sindh Province, Pakistan

Coal test drilling in the Thar Desert of southeast Pakistan was conducted as part of the Coal Exploration and Assessment Program (COALREAP) involving the United States Agency for International Development (USAID), the Geological Survey of Pakistan (GSP), and the U.S. Geological Survey. Drilling was performed in the Thar Desert, or Great Indian Desert, approximately 175 km northeast of Karachi. Twenty five exploration holes were drilled between January 1992 and May 1994. Drill core was described by geologists of the Pakistan Geological Survey and coal samples were analyzed in both the United States and Pakistan. U.S. Geological Survey geologists offered technical assistance, trained GSP personnel, and managed the drilling program according to an agreement with USAID under the Energy Planning and Development Project. Drilling was performed by the Geological Survey of Pakistan. During drilling, the first 50 m was rotary drilled and cuttings collected every 2 m for examination. Average depth for all coal beds is 214 m with a total average thickness of 10 m of coal per drill hole. Core was described, boxed, and stored at the Geological Survey of Pakistan core library at Sonda, near Hyderabad. Approximately 6,412 m of Paleocene to Eocene rock was drilled of which 3,990 m was cored and 1,113 m was rotary drilled. There was 1,309 m of core loss. Geophysical logging of each drill hole permitted detailed thicknesses of coal to be determined. Analysis of the coal indicated a rank of lignite B with an as-received heating value over 5,000 Btu. This report presents data collected at the drill sites and should be used in conjunction with the published interpretive report (Fassett and Durrani, 1994) and the USGS Open-File Report 94-167, which contains analysis of the coal samples. Tables provide quick reference to numeric data and results. Detailed index maps and specific data, for each drill hole are included. This report covers drill holes TP-5 to TP-31. Drill holes TP-16, 17, 21, 26, 27, and 29 were planned but not drilled due to time restraints and (or) a determination that those drill sites were not needed to effectively delineate the coal deposit. The basic data for drill holes TP-1 through TP-4 are included in SanFilipo and others, 1994 however, some data for these drill holes are included for consistency.

Sindh Province↗
USGS1987

Dinosaurs, pollen and spores, and the age of the Ojo Alamo Sandstone, San Juan Basin, New Mexico

The Ojo Alamo Sandstone of the San Juan Basin of New Mexico is composed of interbedded conglomeratic sandstone, sandstone, siltstone, and mudstone. Conglomerates are found in the western part of the basin; siliceous pebbles diminish in size both southward and eastward across the basin, becoming rare to nonexistent in the eastern part. There is great variation in the internal stratigraphy of the Ojo Alamo: Individual sandstone or mudstone beds thicken, thin, and pinch out laterally. The thickness of the Ojo Alamo varies from 6 m (20 ft) to more than 122 m (400 ft). The formation varies in composition from one to as many as five sandstone beds with interbeds of siltstone or mudstone. Dinosaur bone has been found within the Ojo Alamo at several sites in the western part of the basin. Paleocene pollen has been found within the Ojo Alamo in the eastern part of the basin. To date, no Cretaceous pollen has been found at or above the stratigraphic level of dinosaur bone within the Ojo Alamo Sandstone. Near Barrel Spring, in the southwest part of the basin, both dinosaur bone and Paleocene pollen have been found. One bone, found at the top of the Ojo Alamo, was loose on the surface, and its significance is therefore equivocal. Dinosaur bone, however, has also been found in place in the upper part of the Ojo Alamo about 1.6 km (1 mi) west of Barrel Spring, at about the same stratigraphic level as Paleocene pollen from a site just east of Barrel Spring. Because there is no apparent unconformity between the highest in-place bone level and the Paleocene pollen level in this area, the Ojo Alamo dinosaurs, if not reworked, are Paleocene in age at this site and probably throughout the San Juan Basin.

Colorado, New Mexico↗
USGS1987

The ages of the continental, Upper Cretaceous, Fruitland Formation and Kirtland Shale based on a projection of ammonite zones from the Lewis Shale, San Juan Basin, New Mexico and Colorado

The Kirtland Shale or Fruitland Formation directly underlies the Cretaceous-Tertiary boundary throughout most of the San Juan Basin of northwest New Mexico and southwest Colorado. These formations have been known to be Late Cretaceous in age since the early 1900s. Now, with the greatly renewed interest in rocks adjacent to mass extinction boundaries, it is important to place more precise ages on such rock units as the Fruitland and Kirtland. Deposition of the Fruitland and Kirtland was closely related to deposition of the underlying marine-regressive Pictured Cliffs Sandstone. Because the Pictured Cliffs was deposited as a strandline sandstone in a subsiding seaway, its stratigraphic expression, when related to a time horizon (the Huerfanito Bentonite Bed), is a series of rising-to-the-northeast, time transgressive, stair steps. Thus, time lines (or horizons) drawn parallel to the Huerfanito cut through the marine Lewis Shale, the strandline Pictured Cliffs Sandstone, and the continental Fruitland Formation and Kirtland Shale. Ammonites have been collected and identified from various stratigraphic levels within the Lewis Shale around the northwest, north, and east sides of the San Juan Basin. These fossils can be tied in to the established ammonite zonation of the Western Interior seaway. Because some of these ammonite zones have been radiometrically dated outside the San Juan Basin, it is possible to project these dated faunal zones from the Lewis Shale along time lines into the Fruitland Formation and Kirtland Shale and thereby estimate the age of those rocks. Based on these projections the part of the Fruitland and Kirtland laterally time-equivalent to the Lewis Shale is estimated to range from 73.2 ± 0.7 Ma to 73.9 ± 0.8 Ma. The average age for this interval based on these dates is 73.5 ± 0.5 Ma; the maximum range of the interval at the 95 percent confidence level is 71.8 to 75.5 Ma. This age range puts these rocks in the Campanian Stage of the upper Cretaceous in the San Juan Basin.

Colorado, New Mexic↗
USGS1986

The non-transferability of a Cretaceous coal model in the San Juan Basin of New Mexico and Colorado

The San Juan Basin of northwest New Mexico and southwest Colorado contains several Upper Cretaceous coal-bearing formations. The coals in these formations were deposited in environments associated with repeated transgressions and regressions of the Western Interior seaway in Late Cretaceous time. A detailed subsurface and surface study of the coal beds in one of these units, the Fruitland Formation, formed the basis for a coal-depositional model (Fassett and Hinds, 1971). This model basically shows that the thickest Fruitland coals formed landward of thickly stacked sandstone beds of the regressive-marine Pictured Cliffs Sandstone. Transferability of the Fruitland coal model was tested by comparing it to another San Juan Basin coal-bearing rock unit, the lower Menefee Formation. Lower Menefee coal deposits were formed in association with the Point Lookout Sandstone, an older regressive-marine unit. The purpose of this comparison was to see if thick lower Menefee coal beds were also concentrated adjacent to thick vertical shoreface-sandstone buildups. This comparison showed that even though thick sandstone buildups were found in the Point Lookout, no thick coal beds were found in the lower Menefee Formation adjacent to them. This test suggests that certain coal depositional models may have limited value as predictive tools and must be used with caution by coal explorationists. Even more importantly, potential coal-bearing areas should never be written off simply because they do not fit a previously described model.

Colorado, New Mexico↗
USGS1982

Iridium abundance measurements across the Cretaceous/Tertiary boundary in the San Juan and Raton Basins of northern New Mexico

During the past year we have been measuring trace element abundances and searching for anomalously high iridium (Ir) concentrations in continental sedimentary rocks that span the Cretaceous-Tertiary boundary in the Raton and San Juan Basins of northern New Mexico and southern Colorado. Using neutron activation and radiochemical separations, we have identified anomalous concentrations of Ir in samples from two sites in the Raton Basin: in a drill core at York Canyon, about 50 km west of Raton, New Mexico, and in a road cut near the city of Raton. In both cases the anomaly occurs essentially at the base of thin coal beds, across a thickness span of only a few cm and at the same level at which several species of Cretaceous pollen become extinct and the ratio of angiosperm pollen to fern spores drops sharply. The Ir surface density ranges from 8 to 40 × 10 −9 g cm −2 . In the York Canyon core the Ir concentration reaches a value of 5.6 × 10 −9 g/g of rock over a local background of about 10 −11 g/g; the Pt abundance distribution is similar to that for Ir, while Au reaches its maximum concentration about 10 cm below the Ir peak. Se, V, Cr, Mn, Co, and Zn are about two-fold more abundant at the anomaly zone than in adjacent zones, and mass spectrometric 244 Pu analysis showed the 244 Pu/Ir atom ratio ⩽ 1 × 10 7 . In the San Juan Basin we have located a small Ir spike (55 × 10 −12 g/g over a local background of 8 × 10 −12 g/g) that is accompanied by high concentrations of Co and Mn. It is thought to be due to geochemical enrichment processes.

Colorado, New Mexico↗
USGS1967

Core description from GB-1 (Gasbuggy 1) in the northeastern part of the San Juan Basin, Rio Arriba County, New Mexico

The core herein described came from the first test hole drilled for Project Gasbuggy--a project designed to stimulate gas production by the use of nuclear explosives from the Pictured Cliffs Sandstone in the northeastern part of the San Juan Basin, N. Mex. Project Gasbuggy is a cooperative experiment principally involving the El Paso Natural Gas Co., the Atomic Energy Commission, and the U.S. Bureau of Mines. Permission to describe the core from the well was kindly granted by these three organizations.

New Mexico↗