Organic-Carbon Content of Sediments and Rocks from Deep Sea Drilling Project Sites 603, 604, and 605, Western Margin of the North Atlantic

Abstract

The organic matter contents of sediments and rocks sampled during DSDP Leg 93 have been characterized by CHN and Rock-Eval analyses. Most samples from Sites 604 and 605 on the New Jersey continental slope and from Site 603 on the Hatteras outer continental rise contained less than 0.5% organic carbon. Some Neogene samples from the slope contained 1 to 2% organic carbon, and Cretaceous samples from the outer rise were as rich as 13.6% organic carbon by weight. Thin layers of black claystones of Santonian, Cenomanian, and Albian age were found interbedded in organiccarbon-lean, bioturbated, turbiditic claystones. Similar layers of turbiditic black marlstones were interspersed among Neocomian limestones and sandstones. Although the organic matter in many of the samples appeared to be detrital continental material, according to Rock-Eval and C/N values, Cenomanian black shales, in particular, contained substantial proportions of marine-derived organic matter.

Late Cretaceous deep-water agglutinated foraminiferal assemblages from the North Atlantic and its marginal seas

“…In Hole 603B, a re-occurrence is also depicted in Cores 93-603B-26 and 25R (Lower to Middle Campanian biosiliceous event, ,,LMCE@ These assemblages are associated with grayish or greenish-gray claystones, which show slightly increased TOC-values in some cases KATZ, 1987;MEYERS, 1987;RULLKOTTER et al, 1987), thus indicating somewhat oxygen-depleted bottom and interstitial waters (Fig. 3).…”

“…TOC values (column 4) according to HERBIN et ai. (1987), KATZ (1987), MEYERS (1987) and RULLKOTTER et al (1987), specific diversity (number of specimens present in sample) is given in column 5. Thickness is not to scale (only recovered part of each core is taken into account).…”

Sources and deposition of organic matter in Cretaceous passive margin deep-sea sediments: a synthesis of organic geochemical studies from Deep Sea Drilling Project Site 603, outer Hatteras Rise

“…Concentrations of organic carbon are generally very low throughout this claystone unit, as shown in Figure 3 which summarizes data from Meyers (1987). Rock Eval analysis of claystones poor in organic carbon give low hydrogen index values, suggestive of microbially reworked, detrital continental organic matter (Herbin et al, 1987;Katz, 1987;Schaefer and Leythaeuser, 1987;Cunningham and Gilbert, unpublished data).…”

“…Cunningham and Gilbert (unpublished data) determine that 80% of the kerogen in sample 603B-29-1, 121-126 cm, a silty claystone having an organic carbon content of 1.68%, is terrigenous in origin. Meyers (1987) matter or partly oxidized type II marine material. A similar hydrocarbon distribution was found in sample 603B-29-1, 57-62 cm by Herbin et al (1987), although this sample has a hydrogen index of only 34.…”

A Quantitative Study of Lower Cretaceous Cyclic Sequences from the Atlantic Ocean and the Vocontian Basin (Se France)

“…The sedimentary cycles consist of alternations of darker-colored laminated limestone and of lightercolored bioturbated limestone. Color, sedimentary structures, and carbonate content are the most striking and obvious contrasts between laminated limestone and bioturbated limestone, but other differences include their microfossil assemblages, geochemical features, and the concentrations and character of organic matter, clay minerals, and terrestrial clastics [Cotilion and Rio, 1984;Ogg et al, 1987;Dean and Arthur, 1987;Meyer, 1987].…”