Atlantic Continental Shelf and Slope of the United States Sand-Size Fraction of Bottom Sediments, New Jersey to Nova Scotia GEOLOGICAL SURVEY PROFESSIONAL PAPER 529-K Atlantic Continental Shelf and Slope of the United States­ Sand-Size Fraction of Bottom Sediments, New Jersey to Nova Scotia By JAMES V. A. TRUMBULL GEOLOGICAL SURVEY PROFESSIONAL PAPER 529-K Distribution of the sand-size fraction of bottom sediments on the continental margin from New Jersey to Nova Scotia) their source) and local modification processes UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1972 UNITED STATES DEPARTMENT OF THE INTERIOR ROGERS C. B. MORTON, Secretary GEOLOGICAL SURVEY V. E. McKelvey, Director Library of Congress catalog-card No. 72-600176 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402- Price 55 cents (paper cover) Stock Number 2401-2185 CONTENTS Page Page Abstract ----------------------------------------­ K1 Iron-stained grains --------------------------- K25 Introduction ------------------------------------­ 2 Highly rounded and frosted grains ____________ _ 27 Description of area --------------------------­ 2 Sediment types ----------------------------------- 28 Hydrology -----------------------------------­ 4 Modern detrital sediments -------------------- 28 Geologic setting ------------------------------- 4 Protected inshore areas ------------------­ 28 Previous work ------------------------ ______ _ 4 ~earshore beach-sand zone ---------------­ 29 Methods -------------------------------------- 6 Western Gulf of Maine -------------------- 29 Acknowledgments ____________________________ _ 8 Basins on the continental shelf ____________ _ 29 Areal distribution of components __________________ _ 8 Silt deposit south of Martha's Vineyard ___ _ 29 36 Detrital components _________________________ _ 8 Continental slope ------------------------­ Continental rise -------------------------- 37 Rock fragments _______ _ ________________ _ 8 Dark minerals ----------------------------- 10 Relict sediments ------------------------------ 38 Mica ___ ----------------------------------- 12 ~onglaciated shelf south of ~ew England __ _ 38 Quartz and feldspar _____________________ _ 13 Glaciated nearshore shelf south of Glauconite ___ --------------------------- 15 ~ew England -------------------------­ 38 Biogenic components __________________________ _ 18 Georges Bank, ~ antucket Shoals, Great Foraminifera __________________________ _ 18 South Channel ------------------------­ 38 39 Shell fragments _______________________ _ 20 Floor of the Gulf of Maine ---------------­ Other biogenic components ________________ _ 20 Zones of winnowed sand ------------------ 40 Continental shelf near ~ova Scotia _______ _ 40 Authigenic components _______________________ _ 23 ~ ortheast Channel and tips 23 GlauconUe ------------------------------­ of adjacnt banks ---------------------­ 40 Pyrite __ ---------------------------------- 24 41 Limonite ______________________________ _ 24 Organic sediments ---------------------------- Authigenic, residual, and rafted components _ 41 Characteristics of quartz grains _________________ _ 25 Geologic history -----------------------------------­ 41 Roundness ----------------------------------­ 25 Sphericity ----------------------------------- 25 The present regime ------------------------------­ 42 Frosting ------------------------------------- 25 References --------------------------------------- 42 ILLUSTRATIONS Page FIGURE 1. Map of the continental margin off the northeastern coast of the United States, showing sample localities ______ -------------------------------------------------------------- K2 2-7. Contour maps showing percentage of- 2. Sand-sized material in original sample ----------------------------------------------------- 7 3. Rock fragments in sand-size fraction ------------------------------------------------------- 9 4. Dark minerals in sand-size fraction ------------------------------------------------------- 11 5. Mica in sand-size fraction ---------------------------------------------------------------- 13 6. Quartz and feldspar in sand-size fraction --------------------------------------------------- 14 7. All types of glauconite in sand-size fraction ---------------------------------------------·-- 16 8. Map showing inshore limit of glauconite in surface sediment, and inferred present-day extent of sedi- mentary rocks in the Gulf of Maine ---------------------------------------------------------- 17 9. Contour map showing percentage of Foraminifera in sand-size fraction ------------------------------ 19 10. Contour map showing percentage of shell fragments in sand-size fraction -------------------------- 21 11. Map showing distribution of minor biogenic components and pyrite in the sand-size fraction __________ 22 12. Map showing distribution of glauconitic internal molds of Foraminifera --------------------------- 23 13. Contour maps showing variation of characteristics of quartz grains -------------------------------- 26 14. Map and profiles showing topography and composition of sand-size fraction on selected traverses _______ 30 15. Graphs showing average composition and size distribution of surface sediment in individual areas _____ 34 16. Map showing areas of major sediment types and of Holocene and relict sediments ------------------ 36 III ATLANTIC CONTINENTAL SHELF AND SLOPE OF THE UNITED STATES­ SAND-SIZE FRACTION OF BOTTOM SEDIMENTS. NEW JERSEY TO NOV A SCOTIA 1 By JAMES v. A. TRUMBULL ABSTRACT Examination of the sand-size fraction of surface sediments Sand covers most of the continental shelf south of New divides the continental shelf off the Northeastern United England and Long Island and east of northern New Jersey. States into three distinctive areas. These are the glaciated Most of the sand is well sorted and moderately well rounded. Gulf of Maine and Nova Scotia shelf, the shallow high-energy The sand was deposited primarily as glacial and fluvial out­ Georges Bank-Nantucket Shoals area, and the more normal wash during glacial-stage lowering of sea level and was continental shelf south of New England and Long Island and slightly reworked during the following transgression. It is east of New Jersey. therefore relict in origin. Silt on the middle and outer shelf Surface sediments of the Gulf of Maine are predominantly south of Martha's Vineyard apparently postdates the trans­ of relict glacial origin and have been reworked little since gression. River-derived gravel blankets a large area on the deposition. They are poorly sorted, and their sand-size frac­ inner half of the shelf off northern New Jersey. Holocene tion is mostly composed of quartz and feldspar grains, rock detrital sand occurs in a narrow zone off the sandy beaches fragments, and dark minerals. Fine-grained micaceous sedi­ of New Jersey and Long Island. Narragansett Bay, Long ments are being deposited in local basins off the eastern Island Sound, and other protected inshore areas are floored Massachusetts and New Hampshire coasts and in the pro­ primarily with Holocene micaceous silty sediment. tected waters and nearshore basins of the coast of Maine. Over all the continental shelf the primary components of Larger topographic basins nearer the center of the Gulf of the sand-size fraction are quartz and feldspar, with a strong Maine have flat accretionary floors on which clay, some silt, admixture of rock fragments and dark minerals in the sand-size mica flakes, and foraminiferan tests and other glaciated Gulf of Maine and Nova Scotian shelf, and with organic debris are now settling. Basins in areas of high a variable admixture of foraminiferan tests and shell frag­ currents in the eastern and northeastern Gulf of Maine are ments. Locally, very high concentrations of glauconite are mostly covered with relict sand and some gravel, as is found in the bight between New Jersey and Long Island Northeast Channel, the only deep-water hydraulic entrance and south of Long Island. to the gulf. Well-sorted fine quartzose sands inshore of Except in the vicinity of Georges Bank, glauconite appears Georges Bank and inshore of the shallow shelf near Nova to be forming along the entire length of the outer continental Scotia were winnowed from those areas during the postglacial shelf and upper slope. Other authigenic minerals include only transgression and are also now relict. minor amounts of pyrite and possibly limonite. Sediments of most of the Nova Scotia shelf are generally Compared with the shelf sediments, the sand-size fraction similar to the poorly sorted glacially derived rock debris of upper continental slope sediments is enriched in glauconite, of most of the Gulf of Maine, though the Nova Scotia shelf mica, and dark minerals and is impoverished in rock frag­ also contains topographic basins floored with fine-grained ments. The slope sediments off Georges Bank, Northeast sediment. Channel, and the Nova Scotia shelf contain more quartz, feldspar, and rock fragments and less mica and biogenic Georges Bank is more than 50 km from land, but large material than the slope sediments south of New England. The areas of it are less th\.n 60 m deep. Over most of the shallower percentage of foraminiferan tests in the sand fraction in­ parts of the bank little but clean quartz sand and minor creases at the rate of 2.5 percent per 100-meter depth increase amounts of detrital glauconite have survived the constant on the slope south of New England, but the rate is 1.5 percent wave turbulence