(Table 1) Summary of general lithology in IODP Exp302 cores

The Cenozoic ice-rafted debris (IRD) history of the central Arctic is reconstructed utilizing the terrigenous coarse sand fraction in IODP 302 cores from 0 to 273 meters composite depth. This Holocene - middle Eocene quantitative record of terrigenous sand accumulation on the Lomonosov Ridge, along with qualitative information on grain texture and composition, confirms the interpretation that ice initiation (sea ice and glacial ice) occurred ~46 Ma in the Arctic, and provides a long-term pattern of Arctic ice expansion and decay since the middle Eocene. IRD mass accumulation rates range from 0 to 0.13 g/cm2/ka in the middle Eocene and from 0 to 0.36 g/cm2/ka in the Neogene. IRD mass accumulation rate (MAR) maxima in the Miocene and Pliocene cooccur with either glacial initiation or intensification in the sub-Arctic. The 46.25 Ma IRD onset in the central Arctic slightly precedes the earliest evidence of ice in the Antarctic, and compares in timing with a >1000 ppm decrease in atmospheric concentrations of CO2. The decline of pCO2 in the middle Eocene may have driven both poles across the temperature threshold that enabled the nucleation of glaciers on land and partial freezing of the surface Arctic Ocean, especially during times of low insolation.

Total organic carbon, lithology and alkylthiophenes in immature sediments (Table 1)

A series of novel long-chain 3,4-dialkylthiophenes (C36-C54) was identified in a number of sediments ranging from Pleistocene to Cretaceous. The identifications were based on mass spectral characterisation, desulphurisation and mass spectral data of synthesised model compounds. These organic sulphur compounds are probably formed by sulphur incorporation into mid-chain dimethylalkadienes with two methylenic double bonds. These putative precursor lipids are unprecedented and may be considered rather unusual. The distribution of 3,4-dialkylthiophenes in sediments varies considerably with the depositional palaeoenvironment, indicating that these compounds have a potential as molecular markers reflecting changes in palaeoenvironment.

Lithology, biostratigraphy, and geochemistry of the Black Sea sediments, DSDP Leg 42 (pt. 2) data

The monograph presents results of deep-sea drilling in the Black Sea carried out in 1975. Detailed lithological, biostratigraphic and geochemical studies of Miocene-Holocene sediments have been carried out by specialists from institutes of the USSR Academy of Sciences, Moscow State University and other organizations. Drilling results are compared with geophysical data. Geological history of the Black Sea basin is considered as well.

(Table 1) Characteristics of silicified sediments at DSDP Site 61-462 according to host-rock lithology, opal-CT-to-quartz ratio, and the origin of the quartz phase

This study deals with the mineralogical variability of siliceous and zeolitic sediments, porcellanites, and cherts at small intervals in the continuously cored sequence of Deep Sea Drilling Project Site 462. Skeletal opal is preserved down to a maximum burial depth of 390 meters (middle Eocene). Below this level, the tests are totally dissolved or replaced and filled by opal-CT, quartz, clinoptilolite, and calcite. Etching of opaline tests does not increase continously with deeper burial. Opal solution accompanied by a conspicuous formation of authigenic clinoptilolite has a local maximum in Core 16 (150 m). A causal relationship with the lower Miocene hiatus at this level is highly probable. Oligocene to Cenomanian sediments represent an intermediate stage of silica diagenesis: the opal-CT/quartz ratios of the silicified rocks are frequently greater than 1, and quartz filling pores or replacing foraminifer tests is more widespread than quartz which converted from an opal-CT precursor. As at other sites, there is a marked discontinuity of the transitions from biogenic opal via opal-CT to quartz with increasing depth of burial. Layers with unaltered opal-A alternate with porcellanite beds; the intensity of the opal-CT-to-quartz transformation changes very rapidly from horizon to horizon and obviously is not correlated with lithologic parameters. The silica for authigenic clinoptilolite was derived from biogenic opal and decaying volcanic components.

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

Pollen record and lithology of a profile from Dumfriesshire, Scotland

Four samples, G5, G7, G8, and G10, collected by Dr W. W. Bishop from an exposed section in the bank of the River Annan, at Roberthill Farm, Dumfriesshire (S35, 110794) were submitted for pollen analysis (Table I.). The samples, with the exception of the uppermost, were from thin peat layers that lie in the middle of a series of water- laid sands, silts and clays several feet in thickness and now rather strongly arched. The lowermost sample, G5, was taken from an organic layer about | in. thick overlying fine sand and underlying some 2.5 in. of grey, silty fine sand. A narrow layer of sandy peat immediately above the silty, fine sand yielded sample G7, and G8 was collected from a similar peaty layer separated from G7 by more sandy- silty peat. The uppermost sample, G10, was taken from light grey clay 13 in. above sample G8.

Lithology and geochemistry of ODP Leg 198 sites, Shatsky Rise

Samples of chert, porcellanite, and chalk/limestone from Cretaceous chert-bearing sections recovered during Leg 198 were studied to elucidate the nature and origin of chert color zonations with depth/age. Sedimentary structures, trace fossils, compactional features, sediment composition, texture, geochemistry, and diagenetic history were compared among lithologies. Trends in major and minor element composition were determined. Whereas geochemical analyses demonstrate systematic elemental differences among the different lithologies, there are less distinct patterns in composition for the colored cherts. The color of the chert appears to be related primarily to the amount of silica and secondarily to the proportion of other components. Red cherts are almost pure silica with only minor impurities. This may allow pigmentation from fine Fe oxides to dominate the color. These red cherts are from places where geophysical logs indicate that chert is the dominant rock type of the section. These red chert intervals cannot be unequivocally distinguished from surrounding chert-bearing lithologies in terms of sedimentary structures.

Lithology and organic geochemistry at DSDP Hole 77-535

Analyses of extractable organic matter from selected core samples obtained at DSDP Site 535 in the eastern Gulf of Mexico show that the asphalt (or tar) and adjacent oil stains in Lower Cretaceous fractured limestones have a common origin and are not derived from the surrounding organic-matter-rich limestones. Organic matter indigenous to those surrounding limestones was shown to be thermally immature and incapable of yielding the hydrocarbon mixture discovered. In contrast, the oil-stained and asphaltic material appears to be a post-migration alteration product of a mature oil that has migrated from source rocks deeper in the section, or from stratigraphically equivalent but compositionally different source-facies down-dip from the drill site. Further, hydrocarbons of the altered petroleum residues were shown to be similar to Sunniland-type oils found in Lower Cretaceous rocks of South Florida. The results suggest that shallowwater, platform-type source-rock facies similar to those that generated Sunniland-type oils, or deeper-water facies having comparable oil-generating material, are present in this deep-water (> 3000 m) environment. These findings have important implications for the petroleum potential in the eastern Gulf of Mexico and for certain types of deep-sea sediments.

Lithology and organic geochemistry at DSDP Hole 76-534

The organic facies of Early and middle Cretaceous sediments drilled at DSDP Site 534 is dominated by terrestrially derived plant remains and charcoal. Marine organic matter is mixed with the terrestrial components, but through much of this period was diluted by the terrestrial material. The supply of terrestrial organic matter was high here because of the nearness of the shore and high runoff promoted by a humid temperate coastal climate. Reducing conditions favored preservation of both marine and terrestrial organic matter, the terrestrial materials having reached the site mostly in turbidity currents or in the slow-moving, near-bottom nepheloid layer. An increase in the abundance of terrestrial organic matter occurred when the sea level dropped in the Valanginian and again in the Aptian-Albian, because rivers dumped more terrigenous elastics into the Basin and marine productivity was lower at these times than when sea level was high. A model is proposed to explain the predominance of reducing conditions in the Valanginian-Aptian, of oxidizing conditions in the late Aptian, and of reducing conditions in the Albian-Cenomanian. The model involves influx of oxygen-poor subsurface waters from the Pacific at times of high or rising sea level (Valanginian-Aptian, and Albian- Cenomanian) and restriction of that influx at times of low sea level (late Aptian). In the absence of a supply of oxygenpoor deep water, the bottom waters of the North Atlantic became oxidizing in the late Aptian, probably in response to development of a Mediterranean type of circulation. The influx of nutrients from the Pacific led to an increase in productivity through time, accounting for an increase in the proportion of marine organic matter from the Valanginian into the Aptian and from the Albian to the Cenomanian. Conditions were dominantly oxidizing through the Middle Jurassic into the Berriasian, with temporary exceptions when bottom waters became reducing, as in the Callovian. Mostly terrestrial and some marine organic matter accumulated during the Callovian reducing episode. When Jurassic bottom waters were oxidizing, only terrestrial organic matter was buried in the sediments, in very small amounts.

Organic carbon, age, lithology, and CPI-alkenes at DSDP Sites 57-440 and 56-436

"Bound" and "free" solvent-extractable lipids have been examined from Sections 440A-7-6, 440B-3-5, 440B-8-4, 440B-68-2, and 436-11-4. The compound classes studied include aliphatic and aromatic hydrocarbons, ketones, alcohols, and carboxylic acids. Carotenoids and humic acids have also been examined. The quantitative results are considered in terms of input indicators, diagenesis parameters, and structural classes. A difference in input is deduced across the Japan Trench, with a higher proportion of autochthonous components on the western inner trench slope compared with the more easterly, outer trench, wall and greater input in the early Pleistocene than in the Miocene. A variety of diagenetic transformations is observed at Site 440 as sample depth increases. Results are compared with those of samples from Atlantic Cretaceous sediments and from the Walvis Bay high productivity area.