SEARCH · Geology Reports
Results for “Geologic Notes”
Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Volume of organic-rich Devonian shale in the Appalachian Basin: relating "black" to organic-matter content: Geologic notes
Some estimates of natural-gas resources in the Devonian shale of the Appalachian basin depend on the volume of organic-rich shale in the basin. A map by L. G. Wallace and W. de Witt showing the thickness and extent of Devonian "black" shale facies in the Appalachian basin is widely used as an indicator of organic-rich shale, but the map is derived from subjective evaluations of shale color. Wallace and de Witt's definition of "black" is shown here to correspond to an organic-matter content of approximately 4% or more by volume and a Munsell color value for dry pressed-powder samples of about N5 (medium gray) or darker. The volume of Devonian shale with an organic-matter content greater than 2.0% by volume (a definition of "organic-rich" that is preferred by the writers) a erages 1.44 times that of the "black" shale of Wallace and de Witt, and totals about 2,574 × 10 12 cu ft (72.9 × 10 12 cu m) in the Appalachian basin.
Oil possibilities of an area northeast of Petaluma, Sonoma County, California: Geological notes
No abstract available.
Revised age and structural interpretations of Nuka Formation at Nuka Ridge, northwestern Alaska: Geologic notes
New collections of foraminifers and macrofossils from Nuka Ridge, the type area of the enigmatic Nuka Formation, demonstrate that the type Nuka Formation is not a continuous stratigraphic sequence as originally described. Paleontologic evidence indicates the presence of a structurally repeated sequence at Nuka Ridge consisting of Upper Mississippian (Meramec and younger) strata overlain by Permian beds which, in turn, are succeeded by Triassic(?) and Cretaceous rocks. Mississippian calcareous mudstone and limestone units are correlated with the Lisburne Group; microcline-bearing arkose units with Mississippian and Permian macrofossils and microfossils represent the Nuka Formation; units of chert are inferred to be of Permian and Triassic age; and wacke at the top of the sequence resembles unnamed wacke assigned to the Cretaceous elsewhere. These new data and their interpretations indicate that the type section of the Nuka Formation is inadequate. The standard for the Nuka Formation is therefore referred to a newly measured section of the middle arkosic unit of the old section.
VAMPs—Possible hydrocarbon-bearing structures in Bering Sea Basin: Geologic notes
Narrow (1 to 2 km) subsurface columns of concave reflection horizons are common time-base seismic profiles collected in the Bering Sea basin. The columns of recorded downflexures are thought to be velocity pulldowns and commonly are associated with one or more arched or gently domed high-amplitude reflection horizons about 100 m higher in the section. Inferred from this association is that subsurface deposits characterized by anomalously low acoustic velocity are present. We refer to the velocity-anomaly and reflection-amplitude association as a velocity-amplitude feature, or VAMP, and speculate that VAMPs are deep-seated “bright spots” underlain by a strong velocity pulldown possibly caused by gas-charged deposits.
Geologic Field Notes, Geochemical Analyses, and Field Photographs of Outcrops and Rock Samples from the Big Delta B-1 Quadrangle, East-Central Alaska
The U.S. Geological Survey, in cooperation with the Alaska Department of Natural Resources Division of Mining, Land, and Water, has released a geologic map of the Big Delta B-1 quadrangle of east-central Alaska (Day and others, 2007). This companion report presents the major element oxide and trace element geochemical analyses, including those for gold, silver, and base metals, for representative rock units and for grab samples from quartz veins and mineralized zones within the quadrangle. Also included are field station locations, field notes, structural data, and field photographs based primarily on observations by W.C. Day with additions by J.M. O'Neill and B.M. Gamble, all of the U.S. Geological Survey. The data are provided in both Microsoft Excel spread sheet format and as a Microsoft Access database.
Geologic field notes and geochemical analyses of outcrop and drill core from Mesoproterozoic rocks and iron-oxide deposits and prospects of southeast Missouri
The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources/Missouri Geological Survey, undertook a study from 1988 to 1994 on the iron-oxide deposits and their host Mesoproterozoic igneous rocks in southeastern Missouri. The project resulted in an improvement of our understanding of the geologic setting, mode of formation, and the composition of many of the known deposits and prospects and the associated rocks of the St. Francois terrane in Missouri. The goal for this earlier work was to allow the comparison of Missouri iron-oxide deposits in context with other iron oxide-copper ± uranium (IOCG) types of mineral deposits observed globally. The raw geochemical analyses were released originally through the USGS National Geochemical Database (NGDB, http://mrdata.usgs.gov). The data presented herein offers all of the field notes, locations, rock descriptions, and geochemical analyses in a coherent package to facilitate new research efforts in IOCG deposit types. The data are provided in both Microsoft Excel (Version Office 2010) spreadsheet format (*.xlsx) and MS-DOS text formats (*.txt) for ease of use by numerous computer programs.
Geologic studies in Alaska by the U.S. Geological Survey, 1993
This collection of 19 papers continues the annual series of U.S. Geological Survey reports on geologic investigations in Alaska. Contributions include 14 Articles and 5 shorter Geologic Notes that report results from all corners of the State. USGS activities in Alaska cover a broad spectrum of earth science topics, including the environment, hazards, resources, and geologic framework studies. Three articles focus on the environmental geochemistry of parts of south-central, west-central, and southwestern Alaska. An article on methane released from permafrost near Fairbanks and a note on paleowind direction indicators on the Arctic coastal plain contribute to ongoing climate and paleoclimate investigations. Landslide hazards in the Talkeetna Mountains and Wrangell-St. Elias National Park are discussed in two notes. Possible active fault traces near Alaska's main population center are described in an article on the Castle Mountain fault. An article on Aniakchak volcano presents evidence for a previously unrecognized catastrophic flooding event. Resources and resource assessment on gold, base metals, and coal are discussed in several articles and a note. Geologic framework studies cover tectonics, paleontology, stratigraphy, and metamorphic petrology. One contribution involves field methods; it evaluates the relative accuracy of global positioning systems and topographic map-based methods for deriving location data for field stations. Two bibliographies at the end of the volume list reports about Alaska in USGS publications released in 1993 and reports about Alaska by USGS authors in non-USGS publications in 1993.
Drilling, construction, and caliper-log data for wells 3-3204-01, Kaheaka exploratory well, Oahu, Hawaii
The Kaheaka exploratory well (State well number 3-3204-01) was drilled about 3.3 miles southeast of the town of Haleiwa. The well is on agricultural land in the Waialua ground-water area. The well penetrates about 67 feet into a basalt aquifer. Well-construction data, logs of drilling notes, geologic descriptions for the samples, and caliper-log data are presented for the well. The well is one of 12 exploratory wells drilled in the north-central Oahu area between July 1993 and May 1994 in cooperation with the Honolulu Board of Water Supply.
Drilling, construction, and aquifer-test data from wells 3-3307-20 and -21, Thompson Corner exploratory wells I and II, Oahu, Hawaii
The Thompson Corner exploratory wells I and II (State well numbers 3-3307-20 and -21) were drilled near Thompson Corner, about 2.2 miles south-southwest of the town of Haleiwa. The wells are located on agricultural land in the Waialua ground-water area. The wells are about 50 feet apart and penetrate about 90 feet into the ground water. Aquifer tests were conducted using well 3-3307-20 as a pumping well and well 3-3307-21 as an observation well. Well-construction data, logs of drilling notes, geologic descriptions for the samples, and aquifer-test data are presented for the wells. The wells are two of twelve exploratory wells drilled in the north-central Oahu area between July 1993 and May 1994 in cooperation with the Honolulu Board of Water Supply.
Drilling, construction, caliper-log, and specific-conductance data for well 3-3406-12, Twin Bridge Road deep monitor well, Oahu, Hawaii
The Twin Bridge Road deep monitor well (State well number 3-3406-12) was drilled about 2,000 feet northeast of Weed Circle in the town of Haleiwa. The well is on agricultural land. The well penetrates through the freshwater lens and into the freshwater-saltwater transition zone of the Waialua ground-water area to an elevation of -596 feet below mean sea level. Well-construction data, logs of drilling notes, geologic descriptions for the samples, caliper-log, and specific-conductance data are presented for the well. The well is one of 12 exploratory wells drilled in the north- central Oahu area between July 1993 and May 1994 in cooperation with the Honolulu Board of Water Supply.
Drilling, construction, and caliper-log data for wells 3-3406-14 and -15, Helemano exploratory wells I and II, Oahu, Hawaii
The Helemano exploratory wells I and II (State well numbers 3-3406-14 and -15) were drilled near Weed Circle, about 3,000 feet south of the town of Haleiwa. The wells are located on agricultural land in the Waialua ground-water area. The wells penetrate through sedimentary deposits (caprock) and into a basalt aquifer. Both wells have short open intervals cased with well screen at the bottom of the hole, and are cased and sealed through the caprock and basalt to the well screen. The shallow well, Helemano exploratory well I, penetrates about 10 feet into the basalt aquifer below the contact of the caprock and basalt. The deep well, Helemano exploratory well II, penetrates about 210 feet into the basalt aquifer. The deep well has a 20-foot open interval at the bottom. Well construction data, logs of drilling notes, geologic descriptions for drill samples, and caliper-log data are presented for the wells. The wells are two of twelve exploratory wells drilled in the north-central Oahu area between July 1993 and May 1994 in cooperation with the Honolulu Board of Water Supply.
Drilling, construction, and caliper-log data for well 3-3505-25, North Lower Anahulu exploratory well, Oahu, Hawaii
The North Lower Anahulu exploratory well (State well number 3-3505-25) was drilled about 1.4 miles east-northeast of the town of Haleiwa. The well was drilled on agricultural land in the Kawailoa ground-water area. The well was drilled from an elevation of about 232 feet above mean sea level and penetrates about 22 feet into a basalt aquifer. Well-construction data, logs of drilling notes, geologic descriptions for the samples, and caliper-log data are presented for the well. The well is one of 12 exploratory wells drilled in the north-central Oahu area between July, 1993 and May, 1994 in cooperation with the Honolulu Board of Water Supply.
Drilling, construction, and caliper-log data for well 3-3505-26, Opaeula exploratory well, Oahu, Hawaii
The Opaeula exploratory well (State well number 3-3505-26) was drilled about 1.2 miles east- southeast of the town of Haleiwa. The well is located on agricultural land in the Waialua ground-water area. The well was drilled at an elevation of about 287 feet above mean sea level and penetrates about 75 feet into a basalt aquifer. Well-construction data, logs of drilling notes, geologic descriptions for the samples, and caliper-log data are presented for the well. The well is one of 12 exploratory wells drilled in the north-central Oahu area between July 1993 and May 1994 in cooperation with the Honolulu Board of Water Supply.
Drilling, construction, caliper-log, and specific-conductance data for well 3-3604-01, Kawailoa deep monitor well, Oahu, Hawaii
The Kawailoa deep monitor well (State well number 3-3604-01) was drilled about 1.9 miles east- northeast of the town of Haleiwa. The well is on agricultural land in the Kawailoa ground-water area. The well penetrates through the freshwater lens and into the freshwater-saltwater transition zone to an elevation of -392 feet below mean sea level. Well-construction data, logs of drilling notes, geologic descriptions for the samples, specific-conductance and caliper-log data are presented for the well. The well is one of 12 exploratory wells drilled in the north-central Oahu area between July 1993 and May 1994 in cooperation with the Honolulu Board of Water Supply.
Geologic map of the Valdez D-1 and D-2 quadrangles (Mount Wrangell Volcano), Alaska
Geologic Note Mount Wrangell (elev. 4,317 m) is the youngest and only active volcano in the Oligocene to Holocene-aged Wrangell volcanic field that extends from beyond the Alaska-Yukon border northwest through the Wrangell Mountains to the Copper River Basin. The volcano is a very large (900 km 3 ) broad shield containing an ice-filled, nonexplosive, collapse caldera measuring 3.2 by 5.6 kilometers. Three known craters, the West, North, and East occur along the north and west margins of the caldera; the caldera is open to the southeast. The volcano is best exposed on its southwest flank (this map area) where a number of deep glaciated canyons cut through hundreds of meters of shield lava flows creating routes for younger, valley-filling lava flows. The shield extends north into the Gulkana A-1 quadrangle, northeast into the Nabesna A-6 quadrangle, and east into the McCarthy quadrangle where it is almost entirely covered by ice. The present extent of the Mount Wrangell shield showing the entire caldera and locations of the three summit craters is depicted in figure 1. Mount Wrangell was built rapidly beginning about 650 ka by the outpourings of hundreds of voluminous lava flows from a vent, or vents, apparently in the present summit area. By 200 ka to 300 ka, activity waned and only an occasional lava flow coursed down the glacially carved valleys radiating from the summit or flowed over the upper summit area above the heads of the glacial valleys. The youngest dated valley-fill lava flow is approximately 25,000 years old; one or two undated flows may be younger. In historical times there have been several reports of lava flows issuing from the summit area. The most reliable and convincing of these were two independent observations from Copper Center, Alaska on September 3, 1899 that described great earth movements (the 1899 Yakutat Bay earthquake) followed by an eruption at Mount Wrangell’s summit, consisting of vigorous ash emission and flowing lava on the volcano’s northwest flank. This eruptive activity apparently continued for several years after the earthquake, as a photo taken around 1901–02 shows a large part of Mount Wrangell’s summit blanketed by ash. During this study, no evidence of young lava flows in the region were found, although it is very possible that a small-volume flow could be entirely hidden by snow and ice in the 100 years since the event. However, abundant juvenile andesitic pumice was found on the upper Chetaslina Glacier, strongly supporting a very young pyroclastic eruption. In addition to the 1899–1902 eruptions there have been accounts of strong ash-producing activity on at least four different occasions: 1912, July 3, 1921, April 6, 1930, and February 20, 1982. Of these, the 1921 activity was the most spectacular, and possibly erupted from the northeast side of the summit caldera. Present activity is limited to fumaroles in North and West Crater at the summit, at the summit ridge near East Crater, and at two localities at an elevation of 3,657 m on the southwest flank. The summit fumaroles frequently give rise to visible steam plumes, and occasionally sporadic explosive phreatic activity in North and West Crater will put a thin dusting of ash on the summit ice. This study was directed toward Mount Wrangell volcano and the older Wrangell volcanic field rocks that underlie the volcano. These older lavas include the Chetaslina lavas (867 ka–1,650 ka) and a basaltic andesite–dacite center (1,590 ka–1,640 ka) whose source areas are not well defined. Older Paleozoic and Mesozoic sedimentary, igneous, and metamorphic rocks of the Wrangellia terrane underlie the entire Wrangell volcanic field.
A geological reconnaissance in northern Idaho and northwestern Montana, with notes on the economic geology
No abstract available.
Notes on the geology of northeastern New Mexico
In the region of the headwaters of the Canadian is embraced a territory which, for the completeness of its geological record and the interest of its concomitant topographical and scenic features, is not excelled perhaps by a similar extent of country in the West. It is bounded on the west by the Spanish range, which in this part of its course consists of a densely-wooded watershed-divide, 9,000 to 11,000 feet in altitude, from which at intervals lofty lateral spurs are thrown off, whose bald summits overtop by 1,000 to 2,000 feet the actual watershed, which latter extends in a general north-south direction. Near the Colorado line, the range is intersected by the Raton Mountains, a range of gladed hills extending eastward forty or fifty miles, and constituting, with the still easterly prolongation in the Chicorica Mesa, the northern limits of the district, which opens out to the southeastward into the great plain. Thus defined, the district comprises an area of about twenty-five hundred square miles. During the season of 1869, in the progress of his extended reconnaissance of the Rocky Mountains, Dr. Hayden visited this region, from whom we have authentic account of its general geological features, and their intimate relation to those prevailing in other and similar districts to the north and south. A few months' residence in this part of the country in 1874-'75* afforded the writer opportunity to become somewhat familiar with its geological features; and the purpose of the present communication is to present such facts as may tend to contribute something toward a similar knowledge of remote and perhaps hitherto rarely-visited localities, and their connection with already examined districts.