Search USGS⌕ Search

Geology topics

R.E. Mattick

Publications and source records attributed to R.E. Mattick.

9 recordsLinked to original sources
USGS2003

A modern analogue for tectonic, eustatic, and climatic processes in cratonic basins: Gulf of Carpentaria, northern Australia

The Gulf of Carpentaria is a tropical, silled epicontinental sea and may be a modern analogue for ancient cratonic basins. For the purpose of this study, the Gulf of Carpentaria is compared to Pennsylvanian cratonic basins of the United States. During the Pennsylvanian, the North American continent moved from the Southern Hemisphere, through the Equator, into the Northern Hemisphere. Today, the Gulf of Carpentaria–New Guinea region is a few degrees south of the Equator and is moving towards it. During the Pennsylvanian, the world was subjected to major glaciations and associated sea-level changes. The island of New Guinea and the Gulf of Carpentaria have undergone similar processes during the Quaternary. A reconnaissance seismic survey of the gulf conducted by the USGS and the Australian National University (ANU), combined with oil-exploration well data, provided the first step in a systematic evaluation of a modern tropical epicontinental system. During the Cenozoic, the region was dominated by terrestrial sedimentation in a temperate climate. At the same time, carbonates were being deposited on the northern shelf edge of the Australian Plate. During the Miocene, carbonate deposition expanded southward into the gulf region. Then in the Late Miocene, carbonate sedimentation was replaced by terrigenous clastics derived from the developing Central Range of the island of New Guinea, which developed a wetter climate while moving northwards into the tropics. At least 14 basin-wide transgressive–regressive cycles are identified by channels that were eroded under subaerial conditions since about the Miocene. Comparison of the modern Gulf of Carpentaria sequences with those of the Pennsylvanian reveals many similarities.

Gulf Of Carpentaria↗
USGS1994

Third-order Middle Miocene-Early Pliocene depositional sequences in the prograding delta complex of the Pannonian Basin

Few studies exist in the geologic literature that show the distribution of seismic facies and depositional sequences within a lacustrine basin. The Pannonian Basin of Central Europe offers a unique opportunity to evaluate the influence of the eustatic signal on lacustrine deposition. Seismic stratigraphie and sedimentological studies indicate that the Middle Miocene-Early Pliocene infill of the transtensional Pannonian Basin was formed by large delta systems. Systematic sequence stratigraphie analysis of 6000 km of reflection seismic data and more than 100 hydrocarbon exploration wells in Hungary allowed the identification of twelve third-order sequence boundaries in the late Neogene sedimentary fill. This number of depositional sequences corresponds to that of the published global eustatic curve for this time period. Furthermore, based on magnetostratigraphic and radiometric data, the ages of these depositional sequences can be tentatively correlated with the global eustatic curve. The Pannonian Basin became isolated from the world sea at the Sarmatian/Pannonian (11.5 Ma) boundary and formed a large lake. The stratal patterns and sedimentary facies of individual systems tracts within the lacustrine sequences display the same characteristics as marine depositional sequences. The relatively low rate of thermal subsidence and the high rate of sediment supply resulted in a good sequence resolution. Within the third-order sequences higher-order sequences can be recognized with an average duration of about 0.1-0.5 Ma.

Tectonophysics↗
USGS1978

Refraction studies between Icy Bay and Kayak Island, eastern Gulf of Alaska

Results of five seismic refraction lines shot by the U.S. Geological Survey in the Gulf of Alaska between Icy Bay and Kayak Island indicate the following: (1) The Continental Shelf is underlain by as much as 11 km of sedimentary rock of probable Tertiary age where refraction velocities range from 1.2 to 5.5 kilometers per second; (2) a section approximately 5 km thick, which has velocities of 4.1-5.5 km/s and which could represent the Orca Group (lower Tertiary), is present in the western part of the study area but not in the eastern part; and (3) consistent basement velocities of approximately 7.0 km/s could indicate oceanic crust underlying the continental margin.

Alaska↗
USGS1974

Structural framework of United States Atlantic outer continental shelf north of Cape Hatteras

To assess the area’s hydrocarbon potential, regional geologic and geophysical studies are being conducted by the U.S. Geological Survey to determine the structural framework of the United States Atlantic outer continental shelf (AOCS) north of Cape Hatteras. Preliminary interpretations of geophysical data suggest that the buried ridge under the eastern edge of the AOCS in the Baltimore Canyon trough area is deeper and farther west than previously suspected. Although it is not observed under the seaward extension of the Cape Fear arch, this ridge can be traced from the south side of the Baltimore Canyon trough northeastward toward the eastern edge of the Georges Bank trough. In the Baltimore Canyon trough area, the ridge seems to be fault controlled and to form the eastern edge of a Mesozoic depocenter in which approximately 12 km of relatively undisturbed post-Paleozoic sediments accumulated. Below a depth of 6 km, rocks previously considered to be crystalline basement instead may be carbonate and/or evaporite sequences of Jurassic age or older which overlie an even deeper crystalline basement. More than 8 km of sediments are present beneath the continental shelf on Georges Bank. The preliminary regional geophysical studies indicate that thick marine sedimentary sections and geologic structures favorable for the accumulation of petroleum apparently exist under the AOCS off the northeastern part of the United States.

Atlantic outer continental shelf↗
USGS1968

Tertiary gold-bearing channel gravel in northern Nevada County, California

The remains of a huge Tertiary gravel-filled channel lie in the area between the South and Middle Yuba Rivers in northern Nevada County, Calif. The deposits in this channel were the site of some of the most productive hydraulic gold mines in California between the 1850's and 1884. The gravel occupies a major channel and parts of several tributaries that in Tertiary time cut into a surface of Paleozoic and Mesozoic igneous and metamorphic rocks. The gravel is partly covered by the remains of an extensive sheet of volcanic rocks, but it crops out along the broad crest of the ridge between the canyons of the South and Middle Yuba Rivers. The lower parts of the gravel deposits generally carry the highest values of placer gold. Traditionally, the richest deposits of all are found in the so-called blue gravel, which, when present, lies just above the bedrock and consists of a very coarse, poorly sorted mixture of cobbles, pebbles, sand, and clay. It is unoxidized, and, at least locally, contains appreciable quantities of secondary sulfide minerals, chiefly pyrite. Information in drill logs from private sources indicates that a 2-mile stretch of the channel near North Columbia contains over half a million ounces of gold dispersed through about 22 million cubic yards of gravel at a grade .averaging about 81 cents per cubic yard. The deposit is buried at depths ranging from 100 to 400 feet. Several geophysical methods have been tested for their feasibility in determining the configuration of the buried bedrock surface, in delineating channel gravel buried under volcanic rocks, and in identifying concentrations of heavy minerals within the gravel. Although the data have not yet been completely processed, preliminary conclusions indicate that some methods may be quite useful. A combination of seismic-refraction and gravity methods was used to determine the depth and configuration of the bottom of the channel to an accuracy within 10 percent as checked by the drill holes. Seismic-refraction methods have identified depressions which are in the bedrock surface, below volcanic rocks, and which may be occupied by gravels. Seismic methods, however, cannot actually recognize the presence of low-velocity gravels beneath the higher velocity volcanic rocks. Electromagnetic methods, supplemented in part by induced-polarization methods, show promise of being able to recognize and trace blue gravel buried less than 200 feet deep. A broad vague magnetic anomaly across the channel suggests that more precise magnetic studies might delineate concentrations of magnetic material. The usefulness of resistivity methods appears from this study to be quite restricted because of irregular topography and the variable conductivity of layers within the gravel.

Circular↗