Using the Fluvial-Lacustrine Interface in a Glaciodeltaic Deposit to Redefine the Valparaiso Moraine, Berrien County, Michigan, USA

The Valparaiso morainic system in eastern Berrien County, southwestern Michigan, is a 10-18 km-wide continuous belt of collapsed glacial landforms. Previously, the composition of the moraine belt was inferred to be of unsorted materials, including coarse- to fine-textured tills, and some stratified deposits. The moraine boundary was defined primarily on classical geomorphic evidence of relative high elevation, "kettled" or "swell & sag" topography, presence of boulders at the surface, steep ice-contact face, etc. Recent mapping, which included well records, geophysics, and test drilling, revealed the moraine to be composed of glacial meltwater deposits, commonly 30 m thick. The deposits include >50 separate glaciodeltaic morphosequences, mostly ice-marginal deltas, graded to proglacial Lakes Madron (new name) and Dowagiac. Both Lake Madron and younger Lake Dowagiac were dammed to the south by the older Kalamazoo moraine and to the west by the retreating edge of the Michigan ice lobe. Each delta grades from ice-contact landforms underlain by coarse-grained facies at its head to non-collapsed landforms underlain distally by fine-grained facies. Proximal deltaic deposits are coarse grained, locally containing boulders and lenses of poorly sorted flowtill with zones of collapsed bedding along ice-contact slopes. A composite section of a delta, derived from a gravel pit exposure extended by a drillhole showed, from top to bottom: 6 m glaciofluvial sand and gravel; 4.5 m deltaic foreset sand, silt, and gravel, dipping 10o SSE; 9 m pebbly sand; 10.5 m ft coarse to medium sand; 8 m medium to very fine sand and silt at the base; overlying 1.7 m of gray silty diamicton. Deltaic glaciofluvial plains of Lake Madron grade from 256 m altitude to distal distributary plains at 241 m, controlled by the lake level and spillway at 239 m. Lake Dowagiac deltas have fluvial plains as high as 250 m graded to distal plain altitudes of 225 m. The Lake Dowagiac spillway crossed older deposits south of Niles, MI. Both lakes discharged through the St. Joseph River valley south across the regional drainage divide. Wide heads of deltas trending ENE within the Valparaiso moraine belt document ice-margin retreat positions, similar to older ice margins within the outer Kalamazoo Moraine. Correlating the elevations of the heads of deltas and the fluvial/lacustrine interface allowed us to group glaciodeltaic morphosequences by outlet/proglacial lake level and therefore, infer the location of nine ice margins at various stages during construction of the Valparaiso Moraine. The resulting map shows shingled deposits from a highly undulating ice margin, rather than the single, linear margin shown on older maps

Seismic-reflection study in Rice County, Kansas

During the summer of 1983, a MiniSOSIE seismic-reflection study was conducted in Rice County in which an 11.2-km (7-mi) 12-fold common depth point (CDP) profile was shot to investigate several local structural and stratigraphic features. The seismic line was oriented east-west, perpendicular to the local structural grain. Several units, ranging from the Arbuckle through the Mississippian limestones, subcrop beneath the basal Pennsylvanian angular unconformity in this area. The subcrop pattern is dominantly north-south and is related to the eastward dip of these units off the Central Kansas uplift. Reflectors in excess of 1,070-m (3,500-ft) depth are detectable on the seismic profile. The deepest reflectors (0.850 secs) correspond to the Precambrian Rice Formation. Good reflectors occur in the lower Paleozoic section corresponding to a local limestone in the Chattanooga Shale and the subjacent Maquoketa-Viola formations. Several limestones in the Upper Pennsylvanian and Permian section also are good reflectors of seismic energy. Stratigraphic features such as local thinning or thickening and channel cuts can be detected in this part of the stratigraphic section. The Lyons anticline, a local north-south-trending structure currently used for gas storage, also is expressed on the seismic line. The seismic profile shows the structural history of this anticline to be long and complex. Initially, the anticline was a broad, symmetric feature possibly related to the formation of the Precambrian Keweenawan rift. Minor growth may have occurred prior to the deposition of the Chattanooga Shale. A third major period of movement occurred during Late Mississippian to Early Pennsylvanian time when a reverse fault developed on the west flank of the structure, thereby making the structure an asymmetric anticline. Minor structural movement occurred again subsequent to the development of the basal Pennsylvanian angular unconformity

Seismic-reflection study in Rice County, Kansas

During the summer of 1983, a MiniSOSIE seismic-reflection study was conducted in Rice County in which an 11.2-km (7-mi) 12-fold common depth point (CDP) profile was shot to investigate several local structural and stratigraphic features. The seismic line was oriented east-west, perpendicular to the local structural grain. Several units, ranging from the Arbuckle through the Mississippian limestones, subcrop beneath the basal Pennsylvanian angular unconformity in this area. The subcrop pattern is dominantly north-south and is related to the eastward dip of these units off the Central Kansas uplift. Reflectors in excess of 1,070-m (3,500-ft) depth are detectable on the seismic profile. The deepest reflectors (0.850 secs) correspond to the Precambrian Rice Formation. Good reflectors occur in the lower Paleozoic section corresponding to a local limestone in the Chattanooga Shale and the subjacent Maquoketa-Viola formations. Several limestones in the Upper Pennsylvanian and Permian section also are good reflectors of seismic energy. Stratigraphic features such as local thinning or thickening and channel cuts can be detected in this part of the stratigraphic section. The Lyons anticline, a local north-south-trending structure currently used for gas storage, also is expressed on the seismic line. The seismic profile shows the structural history of this anticline to be long and complex. Initially, the anticline was a broad, symmetric feature possibly related to the formation of the Precambrian Keweenawan rift. Minor growth may have occurred prior to the deposition of the Chattanooga Shale. A third major period of movement occurred during Late Mississippian to Early Pennsylvanian time when a reverse fault developed on the west flank of the structure, thereby making the structure an asymmetric anticline. Minor structural movement occurred again subsequent to the development of the basal Pennsylvanian angular unconformity

Suitability of high-resolution seismic method to identifying petroleum reservoirs in Kansas--a geological perspective

Kansas has been a part of a stable craton since at least the beginning of the Paleozoic some 550 m. y. ago. The majority of the sedimentary rocks deposited during the last 550 m. y. are products of numerous inundations by shallow seas. Interspersed with these transgressions were periods of erosion, many coinciding with widespread uplift. The distribution of reservoir-quality rocks has been controlled by the varying structural and depositional settings in both time and space. The identification of these reservoirs begins with a knowledge of the geologic history as detailed by the vast subsurface information base, mainly wire line logs and completion records, that is available for Kansas. Seismic profiling has been and will continue to be used effectively to resolve structural traps. The trend in exploration in the midcontinent has been to strengthen the search for reservoirs associated with more subtle structures and difficult-to-find stratigraphic traps. Stratigraphic traps will become increasingly important, particularly within established production trends. The many unconformities in the midcontinent stratigraphic column afford numerous types of trapping geometry such as truncation beneath an unconformity, traps associated with buried valleys, discontinuous onlap onto erosion surfaces, and porosity pinchouts due to changes in original depositional conditions and diagenetic alteration. The most widespread petroleum accumulations in Kansas occur in structural and stratigraphic traps associated with the pre-Pennsylvanian unconformity. Production associated with the unconformity includes numerous lower Paleozoic pay zones which subcrop directly beneath the unconformity in the Sedgwick, Salina, and Anadarko basins; the Arbuckle production on the Central Kansas uplift; and numerous fields which payout from either conglomerates or weathered zones along the unconformity. Considerable production also occurs farther up-section with the Cherokee and Lansing-Kansas City groups, and down-section in the Viola Formation and Simpson Group. In order to demonstrate the potential use of the seismic method in defining subtle traps, synthetic seismograms were produced for selected strata in central Kansas. Critical attributes of reservoir rock and associated strata conducive to seismic stratigraphic processing include the thickness of a potential reservoir bed and its velocity and density contrast with adjacent strata. Thicker strata such as the Morrow and most lower Paleozoic formations may be more easily defined by seismic-stratigraphic methods. In contrast, the stratigraphy of the Pennsylvanian and Permian cyclothems may not be amenable to definition by seismic methods because these units contain heterogenous reservoirs interbedded with other thin strata of similar composition

Mapping the Evolution of Optically-Generated Rotational Wavepackets in a Room Temperature Ensemble of D2_2

A coherent superposition of rotational states in D$_2$ has been excited by nonresonant ultrafast (12 femtosecond) intense (2 $\times$ 10$^{14}$ Wcm$^{-2}$) 800 nm laser pulses leading to impulsive dynamic alignment. Field-free evolution of this rotational wavepacket has been mapped to high temporal resolution by a time-delayed pulse, initiating rapid double ionization, which is highly sensitive to the angle of orientation of the molecular axis with respect to the polarization direction, $\theta$. The detailed fractional revivals of the neutral D$_2$ wavepacket as a function of $\theta$ and evolution time have been observed and modelled theoretically.Comment: 4 pages, 3 figures. Accepted for publication in Phys. Rev. A. Full reference to follow.

Suitability of high-resolution seismic method to identifying petroleum reservoirs in Kansas--a geological perspective

Kansas has been a part of a stable craton since at least the beginning of the Paleozoic some 550 m. y. ago. The majority of the sedimentary rocks deposited during the last 550 m. y. are products of numerous inundations by shallow seas. Interspersed with these transgressions were periods of erosion, many coinciding with widespread uplift. The distribution of reservoir-quality rocks has been controlled by the varying structural and depositional settings in both time and space. The identification of these reservoirs begins with a knowledge of the geologic history as detailed by the vast subsurface information base, mainly wire line logs and completion records, that is available for Kansas. Seismic profiling has been and will continue to be used effectively to resolve structural traps. The trend in exploration in the midcontinent has been to strengthen the search for reservoirs associated with more subtle structures and difficult-to-find stratigraphic traps. Stratigraphic traps will become increasingly important, particularly within established production trends. The many unconformities in the midcontinent stratigraphic column afford numerous types of trapping geometry such as truncation beneath an unconformity, traps associated with buried valleys, discontinuous onlap onto erosion surfaces, and porosity pinchouts due to changes in original depositional conditions and diagenetic alteration. The most widespread petroleum accumulations in Kansas occur in structural and stratigraphic traps associated with the pre-Pennsylvanian unconformity. Production associated with the unconformity includes numerous lower Paleozoic pay zones which subcrop directly beneath the unconformity in the Sedgwick, Salina, and Anadarko basins; the Arbuckle production on the Central Kansas uplift; and numerous fields which payout from either conglomerates or weathered zones along the unconformity. Considerable production also occurs farther up-section with the Cherokee and Lansing-Kansas City groups, and down-section in the Viola Formation and Simpson Group. In order to demonstrate the potential use of the seismic method in defining subtle traps, synthetic seismograms were produced for selected strata in central Kansas. Critical attributes of reservoir rock and associated strata conducive to seismic stratigraphic processing include the thickness of a potential reservoir bed and its velocity and density contrast with adjacent strata. Thicker strata such as the Morrow and most lower Paleozoic formations may be more easily defined by seismic-stratigraphic methods. In contrast, the stratigraphy of the Pennsylvanian and Permian cyclothems may not be amenable to definition by seismic methods because these units contain heterogenous reservoirs interbedded with other thin strata of similar composition

A Pacific University optometry graduate survey

A Pacific University optometry graduate surve

Kink Arrays and Solitary Structures in Optically Biased Phase Transition

An interphase boundary may be immobilized due to nonlinear diffractional interactions in a feedback optical device. This effect reminds of the Turing mechanism, with the optical field playing the role of a diffusive inhibitor. Two examples of pattern formation are considered in detail: arrays of kinks in 1d, and solitary spots in 2d. In both cases, a large number of equilibrium solutions is possible due to the oscillatory character of diffractional interaction.Comment: RevTeX 13 pages, 3 PS-figure

Statistical Description of Acoustic Turbulence

We develop expressions for the nonlinear wave damping and frequency correction of a field of random, spatially homogeneous, acoustic waves. The implications for the nature of the equilibrium spectral energy distribution are discussedComment: PRE, Submitted. REVTeX, 16 pages, 3 figures (not included) PS Source of the paper with figures avalable at http://lvov.weizmann.ac.il/onlinelist.htm