Diatoms, total organic carbon, and total nitrogen of sediment core Dethlingen, Germany

To provide insights into the long-term evolution of aquatic ecosystems without human interference, we here evaluate a decadal- to centennial-scale-resolution diatom record spanning about 12 ka of the Holsteinian interglacial (Marine Isotope Stage 11c). Using a partially varved sediment core from the Dethlingen palaeolake (northern Germany), which has previously been studied for palynological and microfacies signals, we document the co-evolution of the aquatic and surrounding terrestrial environment. The diatom record is dominated by the genera Stephanodiscus, Aulacoseira, Ulnaria and Fragilaria. Based on the diatom assemblages and physical sediment properties, the evolution of the Dethlingen palaeolake can be subdivided into three major phases. During the oldest phase (lasting ~1900 varve years), the lake was ~10-15 m deep and characterized by anoxic bottom-water conditions and a high nutrient content. The following ~5600 years exhibited water depths >20 m, maximum diatom and Pediastrum productivity, and a peak in allochtonous nutrient input. During this phase, water-column mixing became more vigorous, resulting in a breakdown of anoxia. The youngest lake phase (~4000-5000 years) was characterized by decreasing water depth, turbulent water conditions and decreased nutrient loading. Based on our palaeolimnological data, we conclude that the evolution of the Dethlingen palaeolake during the Holsteinian interglacial responded closely to (i) changes within the catchment area (as documented by vegetation and sedimentation) related to the transition from closed forests growing on nutrient-rich soils (mesocratic forest phase) to open forests developing on poor soils (oligocratic forest phase), and (ii) short-term climate variability as reflected in centennial-scale climate perturbations.

(Table 2) Chemistry of the organic matter at DSDP Leg 62 Holes

The wide distribution of sapropelic deposits in the sedimentary cover of the oceans, their Cretaceous age, and their possible oil- and gas-generating characteristics allow us to regard these deposits as a regular global stage in the history of oceanic sedimentation. So, Cretaceous sapropelic deposits are a unique object for study. Cretaceous sapropelic deposits of DSDP Sites 463, 465, and 466, as well as similar sediments of the Atlantic and Indian Oceans, are characterized by enrichment in organic matter, which sometimes reaches 33% (Cape Verde Basin, DSDP Sites 367 and 368). The objective of this study is the elucidation of genesis, paleogeographic environment of sedimentation, and oil-generating potential of Cretaceous sapropelic deposits at these sites. Attention is given to petrographic composition and distribution of the organic matter.

Radiocarbon dating, sedimentation rate, granulometry and organic carbon content of ODP Leg 182 sites

This data report presents sedimentological (grain size) and geochemical (X-ray diffraction, total organic carbon, accelerator mass spectrometry radiocarbon, and percent carbonate) information obtained from the western transect (Sites 1132, 1130, and 1134) and the eastern transect (Sites 1129, 1131, and 1127) in the Great Australian Bight during Leg 182. The purpose is to quantify changing rates of sediment accumulation and changes in sediment type from the late Pleistocene and Holocene, in order to relate these changes to the well-known sea level curve that exists for this time frame. Ultimately, these data can be used to more effectively interpret lithologic variations deeper in the Pleistocene succession, which most likely represent orbitally forced sea level events.

Characteristics, pyrolysis, age, lithology, sedimentation rate, organic matter, and thermal alteration index at DSDP Leg 67 Holes

Marine-derived amorphous organic matter dominates hemipelagic and trench sediments in and around the Middle America Trench. These sediments contain, on the average, 1% to 2% total organic carbon (TOC), with a maximum of 4.8%. Their organic facies and richness reflect (1) the small land area of Guatemala, which contributes small amounts of higher land plant remains, and (2) high levels of marine productivity and regionally low levels of dissolved oxygen, which encourage deposition and preservation of marine organic remains. These sediments have good potential for oil but are now immature. For this reason, gaseous hydrocarbons like the ethane identified in the deep parts of the section, as at Sites 496 and 497, are probably migrating from a mature section at depth. The pelagic sediments of the downgoing Cocos Plate are lean in organic carbon and have no petroleum potential

(Appendix A) Organic facies at DSDP Hole 93-603B

The Palynology of two sections recovered during Leg 93 drilling by the Deep Sea Drilling Project in the continental rise along the western margin of the North Atlantic is reported. In Hole 603B at Site 603, the dinoflagellate stratigraphy indicates that the interval from Cores 603B-82 to 603B-26 ranges in age from late Berriasian to Santonian. The BlakeBahama Formation ranges from late Berriasian to Aptian. The Hatteras Formation ranges from Aptian to Cenomanian, although the uppermost part may be Turonian. Dinoflagellate evidence from the middle part of the Plantagenet Formation indicates an age from late Coniacian or early Santonian to Santonian within the interval of Cores 603B-28 to 603B-26. Magnetic polarity evidence of the stratigraphy of the Early Cretaceous for the western North Atlantic indicates a reliable correlation with the dinoflagellate zonation. The stratigraphic sequence of palynologically defined organic facies in carbonaceous claystone lithologies in Hole 603B shows that organic stratigraphic units consisting predominantly of fecal-pellet-derived, pelagic organic matter (xenomorphic facies) alternate with units consisting predominantly of terrigenous organic matter (tracheal and exinitic facies), corresponding to that described from other sites in the North Atlantic. A terrigenous organic facies is identified for the first time from the Plantagenet Formation. The claystone organic facies and major lithofacies are closely correlated. The tracheal and exinitic facies occur in carbonaceous terrigenous claystones and claystone turbidites associated with sandstone/siltstone terrigenous turbidites. The xenomorphic facies occurs in claystones within pelagic limestones lacking any turbidites, and in blackish, noncalcareous claystones which correlate in age with the marine-carbon-rich sapropels which are widespread in the North Atlantic Cenomanian. This facies also occurs with an admixture of terrigenous organic particles in the Blake-Bahama Formation, but the mixture is consistent with the submarine fan setting of this interval. The concentration of refractory organic matter (carbonized particles) in the micrinitic and carbonized tracheal facies is considered to be the result, at least in part, of the oxidation of sediment buried below a surface slowly accumulating pelagic clays below the carbonate compensation depth. The progressive increase in number of dinoflagellate species per stage through the Early Cretaceous (except for the late Barremian-Aptian) may have resulted indirectly from the generally progressive rise in global sea level during this time. At Site 605, the dinoflagellate stratigraphy across the Cretaceous/Tertiary boundary is remarkably close to that published from the Maestrichtian and Danian of Denmark. The Maestrichtian/Danian boundary is placed precisely within Section 605-66-1 by dinoflagellate evidence, agreeing with that predicted by other microfossils. The new dinoflagellate-cyst-based genus, Pierceites and its new species P. schizocystis, and the new combination P. ( = Trithyrodinium) pentagonum (May) are proposed. Diacanthum hollisteri Habib, type species of Diacanthum, is emended to accommodat e cysts with the archeopyle formulas P3'', 2P2''-3'', 2P3''-4'', and 3P2''-3''-4''.

Finely dispersed fraction of particulate organic matter and primary production in sea water of the Equatorial East Pacific

Qualitative and quantitative evaluation of the finely dispersed fraction of particulate organic matter in sea water is given. It is demonstrated that in the euphotic zone of high productivity waters this fraction constitutes 86%, in waters with low productivity 61%, and in deep waters (>200 m) 53% of the organic carbon in particulate matter. Formation of the finely dispersed fraction and its role in distribution of energy in the detrital food chain of the ecosystem are discussed.

Organic geochemistry of DSDP Leg 41 holes

The black shale encountered in Cretaceous cores of the Cape Verde area during the DSDP Leg 41 are of marine origin and correspond to excellent potential oil source rocks. They have a low content of humic compounds. Pyrolysis assays, chloroformic extracts, and kerogen data attest to a relatively low stage of evolution for samples at Site 367 (Cape Verde Basin). The samples from Site 368 (Cape Verde Rise) are more evolved, and the deeper ones would be located at the beginning of the principal zone of oil formation.

Organic facies and hydrocarbon potential at DSDP Leg 64 Holes

The sediments from the Gulf of California are potentially good sources for oil and gas. They are rich in organic carbon (av. = 1.9%). Sediments from the margins of the Gulf are rich in oil-prone marine-amorphous organic matter. Sediments from Guaymas Basin contain the same material plus abundant subordinate amounts of gas-prone terrestrially derived organic matter. The enrichment of all of these sediments in marine-amorphous components reflects deposition in a highly productive and oxygen-poor water mass. The sediments are thermally immature, except for those altered by hydrothermal activity or by the intrusion of sills. These sediments are extensively cooked and may have lost their potential for hydrocarbon generation.

Estimation of the normal boiling point of organic compounds via group contributions

The normal boiling point is a fundamental thermo-physical property, which is important in describing the transition between the vapor and liquid phases. Reliable method which can predict it is of great importance, especially for compounds where there are no experimental data available. In this work, an improved group contribution method, which is second order method, for determination of the normal boiling point of organic compounds based on the Joback functional first order groups with some changes and added some other functional groups was developed by using experimental data for 632 organic components. It could distinguish most of structural isomerism and stereoisomerism, which including the structural, cis- and trans- isomers of organic compounds. First and second order contributions for hydrocarbons and hydrocarbon derivatives containing carbon, hydrogen, oxygen, nitrogen, sulfur, fluorine, chlorine and bromine atoms, are given. The fminsearch mathematical approach from MATLAB software is used in this study to select an optimal collection of functional groups (65 functional groups) and subsequently to develop the model. This is a direct search method that uses the simplex search method of Lagarias et al. The results of the new method are compared to the several currently used methods and are shown to be far more accurate and reliable. The average absolute deviation of normal boiling point predictions for 632 organic compounds is 4.4350 K; and the average absolute relative deviation is 1.1047 %, which is of adequate accuracy for many practical applications.