Thesis (doctoral)--Universität Bremen, 2006. / Includes bibliographical references (p. 94-100).

With the end of the Cold War, NATO countries have embarked on transformation initiatives within their militaries to address the new security realities of the 21st century. One of the realities that has not changed is the threat posed to modern navies by sea mines. Global proliferation of sea mines, both older variants and advanced designs, has continued to grow and presents a unique challenge to maritime security for NATO. As NATO forces engage in more expeditionary operations, they must be prepared to counter the danger posed by mines from state and non-state actors. This includes ensuring that vital sea lines of communication (SLOCS), strategic chokepoints throughout the world, commercial ports and naval bases remain open and uncontested. In order to meet the challenge of the 21st century mine threat, NATO must continue to develop balanced MCM capabilities that satisfy expeditionary requirements (such as OMCM for in-stride operations) while maintaining effective dedicated forces to conduct sustained MCM operations against more traditional mining operations.

Graduation date: 1968

The opening of the South Atlantic between 140 and 90 m. y. B. P. occurred about two poles of rotation. The initial pole of rotation was maintained until Africa and South America were completely separated. The subsequent removal of restraints imposed by the pre-existing structure of Africa and South America on the early spreading direction permitted a northward migration of the pole of rotation and concomitant reorientation of spreading direction, The NNE trending Cameroon-Gabon and southern Angola coastlines which offset the generally SSE trend of the west African margin between 5°N and the Walvis Ridge are proposed as initial transform offsets of the South Atlantic proto-rift. Location of these initial offsets was controlled by lineations of the Precambrian/Early Paleozoic belts of thermotectonic activity which occur between older, stable cratonic nuclei of Gondwana. Shorter offsets of the continental margin south of the Walvis Ridge and the two major offsets of the west African coastline north of the Walvis Ridge define a pole of rotation at 5°N, 26°w for the initial South Atlantic opening. A set of magnetic anomaly lineations near the continental margins of Angola and southwest Africa is described and named the Benguela sequence. These anomalies were formed during the initial phase of spreading and are displaced right-laterally almost 1000 kilometers across an extension of the continental offset along the southern Angola margin. This offset is named the Benguela Fracture Zone. The Benguela anomalies are correlated with anomalies of the Lynch sequence in the western North Atlantic. The change in direction between the two pre-Cenozoic phases of South Atlantic spreading is dated at roughly 120 m. y. B. P. based upon an extrapolation of the ages of anomalies in the Lynch sequence to the time of reorientation in the South Atlantic. Formation of the South Atlantic quiet zones occurred by sea-floor spreading about a pole of rotation at 21. 5°N, 14. 0°W during the second phase of opening. The present structure of the Walvis Ridge is controlled by nearly orthogonal NE and NW trending faults shown by seismic reflection profiling. The NE trending set of faults approximate small circles of the pole of rotation at 21. 5°N, 14. 0°W and appear to offset the Walvis Ridge topography in a right-lateral sense. Reorientation of spreading would have produced extension across the Benguela Fracture Zone; development of short offset spreading centers along the Benguela Fracture Zone during this reorientation is proposed to explain the right-lateral offsets of the Walvis Ridge topography. Lack of geophysical information on the lower crustal structure prevents a direct explanation of the present elevation of the Walvis Ridge. However the Walvis Ridge is probably underlain by a low density root produced by alteration of the lower crust and upper mantle materials beneath the Benguela Fracture Zone which began during the spreading reorientation. Asymmetric spreading over the Walvis Ridge may have permitted the zone of crustal accretion to remain near the older Benguela Fracture Zone long enough to allow the creation of an anomalously broad low-density root which is responsible for the uplift of the Walvis Ridge. / Graduation date: 1974

The thermal regime of a postulated descending lithospheric slab is calculated. The gravity anomaly associated with such a structure is large in amplitude and long in wavelengh. Observed free-air gravity anomalies in the Pacific Northwest do not indicate a gravitational effect due to a descending slab. Two hypothetical compensation models proposed may mask the effects of the slab. However, a more complex form of compensation seems required. Extraction of long wavelength signals from the gravity record using matched filters is demonstrated. Caution in the interpretation of potential field records by this class of filters is recommended. / Graduation date: 1975

Power spectral analysis using the maximum entropy method is applied to the estimation of depth to the source of magnetic anomalies. The method assumes that the source is two-dimensional and has a magnetization with random intensity. The predictive ability of the maximum entropy technique permits analysis of short segments of data in order to resolve short wavelength variations in source depth. The method does not require knowledge of susceptibilities or the magnetic declination and inclination. An application of the method to theoretical data and observed marine anomalies over the Peru-Chile trench yields encouraging results. Specifically, for the eastern margin of the Nazca plate, analyses generally indicate a continuous magnetic basement extending into the subduction zone. The basement is shallow seaward of the trench axis and deepens as the plate approaches the convergent margin. This apparent deepening is postulated to be due to the thickening of the oceanic crust and the deterioration of its magnetization, possibly caused by the compressional disruption of the basaltic layer. Landward of the trench axis, the depth estimates indicate possible uplift of the oceanic material into the lower slope of the continental margin. / Graduation date: 1976

The continental margin off southern Oregon, which includes the shelf and slope from Cape Blanco to the Oregon-California border, exhibits a distinctive marginal-plateau structural pattern which divides the margin into the continental shelf, the upper continental slope and its associated benches, and the lower continental slope. Lutum transport and deposition have dominated the sedimentary processes on the margin since the start of Holocene time. The structure of the southern Oregon margin is characterized by north-south trending compressional folds, and near-vertical faults which have been down-dropped to the west. Large-scale folds on the upper slope have ponded sediments behind them resulting in the formation of the Klamath Plateau, Cape Blanco Bench, and other bench-like features. Development of the structural pattern is most likely a result of the compressive underthrusting of the oceanic lithospheric plate beneath the southernmost Oregon-northern California margin and the crustal extension which exists throughout the nearby continent and ocean basin. Useful stratigraphic horizons within the late Pleistocene and Holocene margin deposits include Mazama Ash (6600 years B.P.) and several recognizable shifts in the abundance of Radiolaria and planktonic Foraminifera, particularly one dating from 5000-4000 years B.P. Holocene sedimentation rates vary from an average of 10 cm/ 1000 years on the upper slope to an average of 50 cm/1000 years on the lower slope, indicating that the lower slope is out-building and up-building more rapidly than the upper slope. The paleo-depth range of Pliocene fauna in sedimentary rocks from the margin suggests that subsequent to their deposition both uplift and subsidence occurred on the southern Oregon margin. Sediments from the southern Oregon margin consist primarily of olive gray lutite, gray lutite, and sand-silt layers. Olive gray lutite is Holocene in age and is ubiquitous on the margin, with the thickest accumulation (10 m average) found on the lower slope, while the distribution of Holocene lutite on the upper slope is thin and patchy (3-4 m or less). The gray lutite appears to be a late Pleistocene deposit, and the sand-silt layers reflect both ages. The surface sediment distribution pattern on the shelf consists of modern inner shelf sand, modern central shelf mud, and mixed deposits of both types. Relict deposits are present at the shelf edge. The lower slope consists entirely of modern mud, but the surface sediment on the upper slope and benches consists of both modern and relict deposits, and mixtures of the two. The mineralogy of the unconsolidated and consolidated sediments from the margin indicates that the Klamath Mountains have been the dominant source for these deposits since early Tertiary time. This is reflected in the abundance of blue-green hornblende and other heavy minerals indicative of the Mesozoic rocks of the Klamath Mountains; the same source is suggested for the abundant chlorite found in the clay fraction of margin sediments and rocks. There are indications in the mineralogy of lower slope sediments which suggest that the Tertiary strata of the southern Oregon Coast Ranges may be a secondary source for the deposits in this environment. When compared to the upper slope sediments, those from the lower slope have a higher feldspar content, a higher pyroxene-to-amphibole ratio, and an apparently higher illite content. As a result of the Holocene rise in sea level, the deposition of coarse clastics on the southern Oregon margin has been restricted to the inner shelf. Consequently, only the fine-grained lutum discharged from rivers is deposited on the outer margin environments. Submarine topography, oceanographic conditions, and gravity are important factors which effect transport and deposition of lutum on the margin. A model of modern lutum transport by bottom turbid layers and fine-particle suspensate is proposed for the southern Oregon margin. Long-period swell is believed to be responsible for much of the formation of bottom turbid layers on the shelf. Once formed, these turbid layers move north and west over the shelf under the influence of shelf currents, alternating tidal action, and gravity; upon reaching the slope they are funneled into submarine valleys and deposited on the lower slope and adjacent deep sea. Lutum deposited on the upper slope is eventually re-suspended and transported by southerly bottom currents into down-slope valleys; very little lutum remains behind on the upper slope. Deposition of the fine-particle suspensate as well as slumping and other gravitational processes contribute to the lower slope sediments. The end result of modern lutum transport is the continual up-building and out-building of the lower slope. / Graduation date: 1971

Thesis (M. Sc.)--University of Hong Kong, 2008. / Includes bibliographical references (p. 65-66)

Thesis (Ph. D.) - Oregon State University, 1968. / Bibliography: leaves 205-222.

Univ., Diss.--Bremen.