Upper Wisconsinan Submarine End Moraines off Cape Ann, Massachusetts

1985 ◽  
Vol 24 (2) ◽  
pp. 187-196 ◽  
Author(s):  
R.N. Oldale
Keyword(s):  
New England ◽  
Sea Level ◽  
Gulf Of Maine ◽  
Silty Clay ◽  
Seismic Profiles ◽  
Late Wisconsinan ◽  
Water Depths

Seismic profiles across the southwest end of Jeffreys Ledge, a bathymetric high north of Cape Ann, Massachusetts, reveal two end moraines. The moraines overlie upper Wisconsinan glacialmarine silty clay and are composed mostly of subaqueous ice-contact deposits and outwash. They were formed below sea level in water depths of as much as 120 m during fluctuations of a calving ice front. The moraines are late Wisconsinan in age and were formed after the Cambridge readvance, about 14,000 yr B.P., and before the Kennebunk readvance, about 13,000 yr B.P. They represent fluctuations of the ice front during overall retreat of Laurentide ice from the Gulf of Maine and New England.

Evidence for a Postglacial Low Relative Sea-Level Stand in the Drowned Delta of the Merrimack River, Western Gulf of Maine

1983 ◽  
Vol 19 (3) ◽  
pp. 325-336 ◽  
Author(s):  
R. N. Oldale ◽  
L. E. Wommack ◽  
A. B. Whitney
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
New Hampshire ◽  
Gulf Of Maine ◽  
Relative Sea Level ◽  
Radiocarbon Dates ◽  
Late Wisconsinan

AbstractA submerged delta of the Merrimack River, located offshore between Cape Ann, Massachusetts, and the New Hampshire border, indicates a postglacial low relative see-level stand of about −47 m. The low stand is inferred to date to 10,500 yr B.P., but a lack of age control makes this assignment uncertain. A curve based on a late Wisconsinan, high relative sea-level stand of +32m at 13,000 yr B.P., a low stand of −47m at 10,500 yr B.P., and younger radiocarbon dates related to sea-level rise indicates an early postglacial crustal rise of at least 5 m per century.

scholarly journals New Findings on Submerged Patch-reefs and Reefal Carbonate Rocks at Water Depths of 70-100 meters on the Insular Shelf off Miyako-jima, South Ryukyus, Japan

2020 ◽  
Author(s):  
Takahiko Inoue ◽  
Kohsaku Arai
Keyword(s):  
Sea Level ◽  
Tectonic Setting ◽  
Ryukyu Island ◽  
Seismic Profiles ◽  
Offshore Area ◽  
New Findings ◽  
Bathymetric Mapping ◽  
Convex Upward ◽  
Sediment Layers ◽  
Water Depths

Abstract Sub-bottom profiling (SBP) surveys and bathymetric mapping conducted off the shore of Miyako-jima, which belongs to the southern Ryukyus in the Ryukyu Island Arc, have revealed the presence of mound-shaped structures 3-8 m high and 50-120 m wide at depths ranging from 70-100 m. The SBP surveys showed that the mounds possess strong distinct, convex upward reflector shapes at the top, which we interpret as submerged reefs and reefal sediments. Additionally, modern stratified sediment layers that cover these mound-shaped structures indicate that those reefs began forming and advancing shoreward in a back-stepping fashion as a result of sea level rise. An analysis of the mound distribution shown by SBP and multibeam echo sounding (MBES) surveys suggest that they might have been formed during the lowstand stage of sea level change, which includes the last glacial period, because the distribution of these mounds is limited to water depths of 70 m to 100 m, which are deeper than where present-day reefs grow. The SBP images hint that such high-resolution seismic profiles, accompanied by detailed bathymetric mapping off the reefal area, have the potential to provide effective indicators of not only coral reef paleoenvironment development, but also the tectonic setting of this offshore area.

scholarly journals New Findings on Submerged Patch Reefs and Reefal Carbonate Rocks at Water Depths of 70-100 meters on the Insular Shelf off Miyako-jima, Southern Ryukyus, Japan

2020 ◽  
Author(s):  
Takahiko Inoue ◽  
Kohsaku Arai
Keyword(s):  
Sea Level ◽  
Tectonic Setting ◽  
Ryukyu Island ◽  
Seismic Profiles ◽  
Offshore Area ◽  
New Findings ◽  
Bathymetric Mapping ◽  
Convex Upward ◽  
Sediment Layers ◽  
Water Depths

Abstract Sub-bottom profiling (SBP) surveys and bathymetric mapping conducted off the shore of Miyako-jima, which belongs to the southern Ryukyus in the Ryukyu Island Arc, have revealed the presence of mound-shaped structures 3-8 m high and 50-120 m wide at depths of 70-100 m. The SBP surveys showed that the mounds possess strong distinct, convex upward reflector shapes at the top, which we interpret as submerged reefs and reefal sediments. Additionally, modern stratified sediment layers that cover these mound-shaped structures indicate that those reefs began forming and advancing shoreward in a back-stepping fashion as a result of sea-level rise. An analysis of the mound distribution shown by SBP and multibeam echo sounding (MBES) surveys suggest that they might have been formed during the lowstand stage of sea-level change, which includes the Last Glacial Period, because the distribution of these mounds is limited to water depths of 70 m to 100 m, deeper than where present-day reefs grow. The SBP images hint that such high-resolution seismic profiles, accompanied by detailed bathymetric mapping off the reefal area, have the potential to provide effective indicators of not only coral reef paleoenvironment development, but also the tectonic setting of this offshore area.

Radiocarbon Ages from Two Submerged Strandline Features in the Western Gulf of Maine and a Sea-Level Curve for the Northeastern Massachusetts Coastal Region

1993 ◽  
Vol 40 (1) ◽  
pp. 38-45 ◽  
Author(s):  
Robert N. Oldale ◽  
Steven M. Colman ◽  
Glen A. Jones
Keyword(s):  
Sea Level ◽  
Gulf Of Maine ◽  
Coastal Region ◽  
Sea Level Change ◽  
Level Curve ◽  
Radiocarbon Dates ◽  
Level Change ◽  
The North ◽  
Rapid Changes ◽  
Late Wisconsinan

AbstractNew radiocarbon dates provide ages for two submerged strandline features on the Massachusetts inner shelf. These ages provide limited control on a relative sea-level (RSL) curve for the late Wisconsinan and Holocene. The curve indicates a late Wisconsinan high stand of RSL of +33 m about 14,000 yr ago and a very short-lived relative low stand of about -43 m at about 12,000 yr ago followed by a rise to present sea level. Rapid changes of RSL around 12,000 yr ago may be related to changes in global glacial meltwater discharge and eustatic sea-level change shown by dated corals off Barbados. Variations in the magnitude and timing of RSL change from south to north along the coast of the western Gulf of Maine are due to greater crustal depression and later deglaciation to the north.

Delayed Postglacial Uplift and Synglacial Sea Levels in Coastal Central New England

1993 ◽  
Vol 40 (1) ◽  
pp. 46-54 ◽  
Author(s):  
Carl Koteff ◽  
Gilpin R. Robinson ◽  
Richard Goldsmith ◽  
Woodrow B. Thompson
Keyword(s):  
New England ◽  
Sea Level ◽  
Sea Level Change ◽  
Sea Levels ◽  
Flat Surfaces ◽  
Level Change ◽  
Base Level ◽  
Elevation Data ◽  
Ice Retreat ◽  
Late Wisconsinan

AbstractThe postglacial uplift pattern indicated by elevations of ice-marginal glaciomarine deltas in coastal New England, deposited between approximately 15,000 and 14,000 yr B.P. during ice retreat from northeastern Massachusetts into southwestern Maine, is very similar to that previously recorded for glaciolacustrine deltas of similar age from inland areas of New England. Multiple regression analyses of elevations from both sets of deltas show an extremely close fit to tilted flat surfaces that rise 0.852 m/km to the N 28.5°W along the coast and 0.889 m/km to the N 20.5°W in western New England. The close similarity of uplift pattern in areas where elevation data are from different base-level media, along with additional shore-line evidence, indicates (1) that both areas are part of the same crustal postglacial uplift block, (2) that postglacial uplift was delayed until after 14,000 yr B.P., and (3) that little or no eustatic sea-level change occurred between 15,000 and 14,000 yr B.P., during which time the margin of the late Wisconsinan Laurentide ice sheet retreated about 100 km from Boston, Massachusetts, into southwestern Maine. Elevation data from even younger glaciomarine deltas in the coastal area indicate that soon after the ice margin reached southwestern Maine and adjacent New Hampshire (ca, 14,000 yr B.P.), eustatic sea level rose rapidly 7-10 m during the time that the ice margin retreated 5-10 km, which may have occurred during an interval of only 50-100 yr, Our new data not only confirm the delayed postglacial uplift model previously described for western New England, but also indicate that little or no eustatic sea-level change occurred during a substantial period of early deglaciation. However, at about 14,000 yr B.P., sea level rose rapidly. Postglacial uplift in the region apparently began between 14,000 and 13,300 yr B.P., before the retreating ice margin reached eastern Maine.

THE STRUCTURE OF THE NATURALISTE PLATEAU AND TROUGH

1977 ◽  
Vol 17 (1) ◽  
pp. 3 ◽  
Author(s):  
Derk Jongsma ◽  
Peter Petkovic
Keyword(s):  
Sea Level ◽  
Early Cretaceous ◽  
Continental Margin ◽  
Deep Sea ◽  
Magnetic Anomalies ◽  
Seismic Profiles ◽  
Northern Margin ◽  
Reflection Seismic ◽  
Southwest Australia ◽  
Water Depths

The Naturaliste Plateau is a broad, relatively flat feature lying at a depth below sea level of around 2500 m off the continental margin of southwest Australia. A northerly trending trough with water depths of 3000 to 4000 m separates the Plateau from the continental shelf. Reflection seismic profiles over the Plateau reveal 500 to 1000 m thicknesses of post-Neocomian sediments on the Plateau and up to 2000 m thicknesses in the Trough. An erosional unconformity which is thought to be of Neocomian age separates folded, faulted sediments and intruded metamorphic and igneous basement from the overlying sediments. Deep sea drilling has shown the upper section as being composed of deep-sea clays and oozes. Several hiatuses occur in this upper section.Magnetic anomalies over the Plateau are intense and have magnitudes of up to 850 nT. The anomalies are much more subdued over the Trough. Depths to the bodies causing the magnetic anomalies are estimated to be between zero and three km below the Neocomian unconformity. The gravity field over the Plateau indicates that the crust is of intermediate thickness. A phase of rifting in the Early Cretaceous gave rise to a gently sloping northern margin, whereas rifting in the Eocene produced a steep, faulted, southern margin. The Plateau appears to have been at its present depths since the Early Cretaceous. Prospectivity for petroleum over the Plateau and Trough is poor.

A Late Wisconsinan Marine Incursion into Cape Cod Bay, Massachusetts

1988 ◽  
Vol 30 (3) ◽  
pp. 237-250 ◽  
Author(s):  
Robert N. Oldale
Keyword(s):  
New England ◽  
Sea Level ◽  
Cape Cod ◽  
Seismic Reflection Data ◽  
Marine Deposits ◽  
Reflection Data ◽  
Cape Cod Bay ◽  
Terminal Zone ◽  
Glacier Ice ◽  
Late Wisconsinan

Reinterpretation of seismic-reflection data from Cape Cod Bay has produced a revised late Wisconsinan history. Acoustically laminated deposits, originally inferred to be glaciolacustrine, are shown to be glaciomarine by tracing them to glaciomarine mud in Stellwagen Basin, north of Cape Cod Bay. A late Wisconsinan marine deposit of nonglacial origin overlies the glaciomarine deposits in Cape Cod Bay. Both deposits indicate that the crust was isostatically depressed below the late Wisconsinan eustatic sea level and that deglaciation and marine submergence occurred simultaneously. Valleys cut into the marine deposits, both glacial and nonglacial, indicate that a low sea-level stand, the result of isostatic rebound, occurred shortly after the marine incursion. A transgressive uncomformity and marine deposits, both mostly of Holocene age, overlie the late Wisconsinan deposits. The marine incursion, regression, and Holocene transgression represent the northward passage of an isostatically induced peripheral bulge following deglaciation. In turn, the bulge, a response to crustal loading and unloading, indicates thick glacier ice in the terminal zone and lends support to arguments for a maximum Laurentide ice model. Evidence for a late Wisconsinan marine incursion, regression, and the passage of a peripheral bulge should be sought in the other bays and sounds of the New England terminal zone.

scholarly journals New findings on submerged patch reefs and reefal carbonate rocks at water depths of 70–100 m on the insular shelf off Miyako-jima, southern Ryukyus, Japan

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Takahiko Inoue ◽  
Kohsaku Arai
Keyword(s):  
Sea Level ◽  
Tectonic Setting ◽  
Ryukyu Island ◽  
Seismic Profiles ◽  
Offshore Area ◽  
New Findings ◽  
Bathymetric Mapping ◽  
Convex Upward ◽  
Sediment Layers ◽  
Water Depths

Abstract Sub-bottom profiling (SBP) surveys and bathymetric mapping conducted off the shore of Miyako-jima, which belongs to the southern Ryukyus in the Ryukyu Island Arc, have revealed the presence of mound-shaped structures 3–8 m high and 50–120 m wide at depths of 70–100 m. The SBP surveys showed that the mounds possess strong distinct, convex upward reflector shapes at the top, which we interpret as submerged reefs and reefal sediments. Additionally, modern stratified sediment layers that cover these mound-shaped structures indicate that those reefs began forming and advancing shoreward in a back-stepping fashion as a result of sea-level rise. An analysis of the mound distribution shown by SBP and multibeam echo sounding (MBES) surveys suggest that they might have been formed during the lowstand stage of sea-level change, which includes the Last Glacial Period, because the distribution of these mounds is limited to water depths of 70 to 100 m, deeper than where present-day reefs grow. The SBP images hint that such high-resolution seismic profiles, accompanied by detailed bathymetric mapping off the reefal area, have the potential to provide effective indicators of not only coral reef paleoenvironment development, but also the tectonic setting of this offshore area.

A sea-level curve for the Canadian Beaufort Shelf

1985 ◽  
Vol 22 (10) ◽  
pp. 1383-1393 ◽  
Author(s):  
Philip R. Hill ◽  
Peta J. Mudie ◽  
Kate Moran ◽  
Steve M. Blasco
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
Laurentide Ice Sheet ◽  
Shelf Area ◽  
Mackenzie Delta ◽  
Seismic Profiles ◽  
Acoustic Data ◽  
Basin Subsidence ◽  
Late Wisconsinan ◽  
A Minor

Radiocarbon-dated peat and peaty clay samples from geotechnical boreholes in the Canadian Beaufort continental shelf have been used to reconstruct a late Quaternary relative sea-level (RSL) curve. The samples were carefully selected and evaluated using palynological techniques, to ensure that reasonable age error limits could be given to each sample. The dated samples were then related to the local geological setting, using seismic profiles to determine the environment of deposition. The resulting data show a rise of 140 m in RSL since 27 000 years BP. A minor lowering of RSL at some time between 20 000 and 10 000 years BP is inferred from acoustic data. Contributions from basin subsidence, sediment loading, and consolidation account for 35 m of the total RSL rise. The RSL curve is interpreted in the light of recent models of the isostatic and eustatic responses of the Earth's crust at the Laurentide ice-sheet margin. Ice may have been more extensive during the middle Wisconsinan than previously thought and may have caused the major lowering of sea level in the shelf area. This ice may have advanced to within several hundred kilometres of the Mackenzie Delta – Tuktoyaktuk Peninsula coast. An ice readvance of late Wisconsinan age probably caused a subsequent minor lowering of RSL.

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