Analysis and Interpretation of Ice-Deformed Sediments from Harrison Bay, Alaska

The surficial sediments present on the continental shelf off the north coast of Alaska in the vicinity of Harrison Bay consist dominantly of fine grained sand, silt, and mud that were deposited during Holocene time. Depositional environments in Harrison Bay range from outer shelf to prodelta and delta front. Ice sediment interaction has overprinted structural deformation on many of the sediments present in Harrison Bay, and has in some cases obliterated the original lithologic continuity of the sediments. Ice related deformation ranges from simple loading features to more complex folded and faulted structures. A hypothetical model has been proposed which relates the type of deformational features found in recent sediments from an ice impacted area to the process of ice gouging. The deformational structures observed in the sediments from Harrison Bay were compared to deformational features found in sediments from ancient environments that are known to have had floating ice present. The results indicate that structures found in the modern environment bear a remarkable similarity to structures found in the ancient environments, and that the structures found in the ancient environments are believed to have been caused by the process of ice gouging

Childhood Lead Exposure in the Palestinian Authority, Israel, and Jordan: Results from the Middle Eastern Regional Cooperation Project, 1996–2000

In the Middle East, the major sources of lead exposure have been leaded gasoline, lead-contaminated flour from traditional stone mills, focal exposures from small battery plants and smelters, and kohl (blue color) in cosmetics. In 1998–2000, we measured blood lead (PbB) levels in children 2–6 years of age in Israel, Jordan, and the Palestinian Authority (n = 1478), using a fingerstick method. Mean (peak; percentage > 10 μg/dL) PbB levels in Israel (n = 317), the West Bank (n = 344), Jordan (n = 382), and Gaza (n = 435) were 3.2 μg/dL (18.2; 2.2%), 4.2 μg/dL (25.7; 5.2%), 3.2 μg/dL (39.3; < 1%), and 8.6 μg/dL (> 80.0; 17.2%), respectively. High levels in Gaza were all among children living near a battery factory. The findings, taken together with data on time trends in lead emissions and in PbB in children in previous years, indicate the benefits from phasing out of leaded gasoline but state the case for further reductions and investigation of hot spots. The project demonstrated the benefits of regional cooperation in planning and carrying out a jointly designed project

Lithofacies, Architecture and Sequence Stratigraphic Interpretation of the Upper Pennsylvanian Indian Cave Sandstone, Northern Midcontinent Shelf, U.S.A. (southeastern Nebraska).

The Virgilian “Indian Cave Sandstone” (ICS) is herein redefined as at least four incised valley fills (IVFs) of at least two different ages. These IVFs are composed of irregularly bounded, tabular-lenticular units of trough cross-bedded sandstone, grading vertically into tabular-lenticular units of mudstone-and-sandstone-dominated heterolith. Three IVFs, wider (\u3c 2 km) than they are deep (\u3e 30 m), are composed of multiple storeys grading upward from fluvial-to-estuarine facies to upper-estuarine facies. Storey boundaries are delineated by bounding surfaces underlying conglomerates with heterolithic clasts. One IVF (Honey Creek, NE) is smaller than the others, (\u3e 0.5 km wide and \u3e 25 m deep) and appears to be composed of a single-storey fill dominated by fluvial-toestuarine facies. A sequence boundary delineates the base of each IVF, with lowstand, transgressive, and highstand system tracts represented by vertical changes in lithology. Sequence boundaries are delineated by bounding surfaces underlying conglomerates with carbonate and mudrock clasts of the cyclothem host rocks. Outside of the confines of the IVFs, sequence boundaries are correlated to the position of interfluve paleosols interpreted to be contemporaneous with the IVFs. Two IVFs (Peru and Shubert, NE), are younger than previously believed,and contain a record of at least 30 m of relative sea-level change. The top of the third IVF (Brownville, NE) has been modified by Quaternary erosion and the base is not exposed, thus the exact stratigraphic position and associated relative sea-level change cannot be determined. The Honey Creek IVF is the oldest and smallest lithosome, and also is the only unit with an upper bounding surface that meets the original stratigraphic definition of the ICS. These deposits represent the filling of accommodation on the high Midcontinent shelf during periods of fluctuating relative sea-level. The IVFs and associated paleosols correlate to regional paleosols identified as fifth order sequence boundaries by other investigators. Thus, relative sea-level changes of at least (or \u3e) 30 m can be correlated to fifth order cycles. Advisor: Christopher R. Fieldin

Analysis and interpretation of ice-deformed sediments from Harrison Bay, Alaska

The surficial sediments present on the continental shelf off the north coast of Alaska in the vicinity of Harrison Bay consist dominantly of fine grained sand, silt, and mud that were deposited during Holocene time. Depositional environments in Harrison Bay range from outer shelf to prodelta and delta front. Ice sediment interaction has overprinted structural deformation on many of the sediments present in Harrison Bay, and has in some cases obliterated the original lithologic continuity of the sediments. Ice related deformation ranges from simple loading features to more complex folded and faulted structures. A hypothetical model has been proposed which relates the type of deformational features found in recent sediments from an ice impacted area to the process of ice gouging. The deformational structures observed in the sediments from Harrison Bay were compared to deformational features found in sediments from ancient environments that are known to have had floating ice present. The results indicate that structures found in the modern environment bear a remarkable similarity to structures found in the ancient environments, and that the structures found in the ancient environments are believed to have been caused by the process of ice gouging

Lithofacies, architecture and sequence stratigraphic interpretation of the upper Pennsylvanian Indian Cave Sandstone, Northern Midcontinent Shelf, United States of America (southeastern Nebraska)

The Virgilian Indian Cave Sandstone (ICS) is herein redefined as at least four incised valley fills (IVFs) of at least two different ages. These IVFs are composed of irregularly bounded, tabular-lenticular units of trough cross-bedded sandstone, grading vertically into tabular-lenticular units of mudstone-and-sandstone-dominated heterolith. Three IVFs, wider (\u3c2 km) than they are deep (\u3e30 m), are composed of multiple storeys grading upward from fluvial-toestuarine facies to upper-estuarine facies. Storey boundaries are delineated by bounding surfaces underlying conglomerates with heterolithic clasts. One IVF (Honey Creek, NE) is smaller than the others, (\u3e0.5 km wide and \u3e25 m deep) and appears to be composed of a single-storey fill dominated by fluvial-to-estuarine facies. A sequence boundary delineates the base of each IVF, with lowstand, transgressive, and highstand system tracts represented by vertical changes in lithology. Sequence boundaries are delineated by bounding surfaces underlying conglomerates with carbonate and mudrock clasts of the cyclothem host rocks. Outside of the confines of the IVFs, sequence boundaries are correlated to the position of interfluve paleosols interpreted to be contemporaneous with the IVFs. Two IVFs (Peru and Shubert, NE), are younger than previously believed, and contain a record of at least 30 m of relative sea-level change. The top of the third IVF (Brownville, NE) has been modified by Quaternary erosion and the base is not exposed, thus the exact stratigraphic position and associated relative sea-level change cannot be determined. The Honey Creek IVF is the oldest and smallest lithosome, and also is the only unit with an upper bounding surface that meets the original stratigraphic definition of the ICS. These deposits represent the filling of accommodation on the high Midcontinent shelf during periods of fluctuating relative sea-level. The IVFs and associated paleosols correlate to regional paleosols identified as fifth order sequence boundaries by other investigators. Thus, relative sea-level changes of at least (or \u3e) 30 m can be correlated to fifth order cycles

Fluvial-estuarine reinterpretation of large, isolated sandstone bodies in epicontinental cyclothems, Upper Pennsylvanian, northern Midcontinent, USA, and their significance for understanding late Paleozoic sea-level fluctuations

The Upper Pennsylvanian Indian Cave Sandstone (ICS) in southeastern Nebraska is herein reinterpreted as three multistory incised valley fills and one single-storey channel fill, altogether representing at least two different intervals of time. ICS lithosomes are linear bodies, as much as 2000 m wide and 30 m thick, incised into pre-existing cyclothems, and have relatively steep sides and flat bases. They include crudely fining-upwards successions of trough cross-bedded sandstones, interpreted as tidally-influenced fluvial deposits, overlain by upper estuarine heterolithic facies, with local coals, and a restricted trace fossil assemblage. The vertical facies succession suggests sediment accumulation in a regime of gradually increasing accommodation, i.e., during rising relative sea level. The basal erosion surfaces of ICS bodies can be traced out onto the adjacent interfluves where they correspond to well-developed paleosols, indicating sequence boundaries. Furthermore, the sequences defined herein can be correlated closely with recently published sequence stratigraphic frameworks from the region, suggesting that the ICS bodies record repeated, fifth-order (Milankovitch band), relative sea-level fluctuations of a minimum of 30 m during latest Pennsylvanian time Significantly, this estimate is half or less of those made by many other studies. Such a local quantification of relative sea-level change provides a critical constraint on eustatic sea-level fluctuation during the late Paleozoic Gondwanan Ice Age