Glaciotectonic deformation associated with the Orient Point-Fishers Island moraine, westernmost Block Island Sound: further evidence of readvance of the Laurentide ice sheet
Geo-Marine Letters
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Abstract
High-resolution seismic-reflection profiles collected across pro-glacial outwash deposits adjacent to the circa 18 ka b.p. Orient Point–Fishers Island end moraine segment in westernmost Block Island Sound reveal extensive deformation. A rhythmic seismic facies indicates the host outwash deposits are composed of fine-grained glaciolacustrine sediments. The deformation is variably brittle and ductile, but predominantly compressive in nature. Brittle deformation includes reverse faults and thrust faults that strike parallel to the moraine, and thrust sheets that extend from beneath the moraine. Ductile deformation includes folded sediments that overlie undisturbed deposits, showing that they are not drape features. Other seismic evidence for compression along the ice front consists of undisturbed glaciolacustrine strata that dip back toward and underneath the moraine, and angular unconformities on the sea floor where deformed sediments extend above the surrounding undisturbed correlative strata. Together, these ice-marginal glaciotectonic features indicate that the Orient Point–Fishers Island moraine marks a significant readvance of the Laurentide ice sheet, consistent with existing knowledge for neighboring coeval moraines, and not simply a stillstand as previously reported.
Suggested Citation
Poppe, L., Oldale, R.N., Foster, D.S., Smith, S.M., 2012, Glaciotectonic deformation associated with the Orient Point-Fishers Island moraine, westernmost Block Island Sound: further evidence of readvance of the Laurentide ice sheet: Geo-Marine Letters, v. 32, no. 4, p. 279-288, https://doi.org/10.1007/s00367-012-0296-9.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Glaciotectonic deformation associated with the Orient Point-Fishers Island moraine, westernmost Block Island Sound: further evidence of readvance of the Laurentide ice sheet |
| Series title | Geo-Marine Letters |
| DOI | 10.1007/s00367-012-0296-9 |
| Volume | 32 |
| Issue | 4 |
| Publication Date | June 29, 2012 |
| Year Published | 2012 |
| Language | English |
| Publisher | Springer |
| Publisher location | Amsterdam, Netherlands |
| Contributing office(s) | Woods Hole Coastal and Marine Science Center |
| Description | 10 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Geo-Marine Letters |
| First page | 279 |
| Last page | 288 |
| Country | United States |
| State | New York |
| Other Geospatial | Orient Point;Fishers Island;Block Island Sound |