The geologic history of the passive margin off new england and the canadian maritime provinces

The geologic history of the passive continental margin off the east coast of North America from New England to Newfoundland is described using all available geological and geophysical information. “Rift” and “drift” phases of the margin's evolution are recognized, with rifting initiated in Late Triassic and completed by Early Jurassic. The plate decoupling process created a complex block-faulted terrain as a result of uplift and tensional fracturing. The approximate plane of continental separation is marked by a “hinge zone” characterized by a pronounced steepening of basement gradients. Since the Early Jurassic, the margin has undergone continual subsidence in response to cooling and sediment loading. This “drift” sequence attains its maximum thickness in the vicinity of the continental slope and thins both landward and seaward. On the shelf, this unit consists of Mesozoic evaporites, carbonates, and deltaic deposits. Overlying these sediments is a prograding wedge of Cenozoic elastics. On the rise, the Mesozoic sediments are evaporites, hemipelagic limestones and shales and carbonaceous clays. The Cenozoic is dominantly terrigenous material. Separating these two sedimentary provinces is the continental slope, a site of major facies changes and a Mesozoic reef complex.     

Shasta ground sloth (Nothrotheriops shastense hoffstetter) at Shelter Cave, New Mexico: Environment, diet, and extinction

Seven coprolites of the extinct Shasta ground sloth (Nothrotheriops shastense) were recently discovered in the Los Angeles County Museum collection from Shelter Cave, New Mexico. Three dung balls provided radiocarbon ages of 11,330, 12,330 and 12,430 yr B.P. Packrat (Neotoma) middens disclose a xeric juniper woodland at Shelter Cave during the sloth's occupation. Plant cuticles from the dung indicate that the ground sloth had a diet dominated by mormon tea (Ephedra) and other xerophytic shrubs. Pollen spectra from the coprolites have high representations of anemophilous plants and low representations of the dietary items shown in the cuticle analysis.Fifteen radiocarbon dates of sloth dung obtained since 1974 strengthen the hypothesis that sloth extinction occurred about 11,000 yr B.P. Paleoenvironmental studies indicate that ground sloths lived in juniper woodlands and montane conifer communities. Nothrotheriops commonly dined on shrubs that are still present in these habitats. It is difficult to explain the demise of the Shasta ground sloth by climatic change or dietary stress. Human predation remains as a possible explanation; ground sloth extinction appears to coincide with the time of Clovis mammoth hunters.     

Carbon content and carbonate 13C abundances in the Early Precambrian Swaziland sediments of South Africa

Carbon content (0.02–0.68% organic), carbonate content (0–69.7%) and carbonate ¹³C abundances (${}^{\mathrm{?}}\text{7.5?+2.3‰}$) were obtained on samples from the Swaziland sediments of South Africa, which are among the oldest known sedimentary rocks on earth (> 3·10⁹ years old). The carbon chemistry of these sediments may serve as evidence for early life and/or for products of chemical evolution. The variation of organic and carbonate carbon concentrations in different sedimentary horizons seems to be controlled by differences in depositional and diagenetic histories. The carbonate δ ¹³C values did not vary significantly from the ordinary range of Phanerozoic limestone values.     

检测海洋弧菌的酶联免疫吸附试验研究

研究建立中国对虾病原菌┐副溶血弧菌（Ｖｉｂｒｉｏｐａｒａｈａｅｍｏｌｙｔｉｃｕｓ）的间接酶联免疫吸附试验（ＥＬＩＳＡ）快速检测技术。间接ＥＬＩＳＡ技术中的副溶血弧菌的特异抗血清由家兔制备，羊抗兔ＩｇＧ用碱性磷酸酶标记，酶的底物为对磷酸基硝基苯。将该技术标准化后，测定了抗血清与１３株其它副溶血弧菌菌株及２９株其它弧菌标准菌株的交叉反应，并进行了苗期对虾样品中副溶血弧菌的检测     

Histochemistry as a tool for examining possible pathologic cause-and-effect relationships between heavy metal and inflammatory lesions in oysters, Crassostrea virginica

Unexplained inflammatory lesions have been seen on many occasions in oysters (Crassostrea virginica) that have been examined by histopathologic methods. Application of the Mallory's hematin and the rubeanic acid methods for demonstration of copper in histologic sections revealed strong staining reactions in granules of some, but not all, granular hemocytes. These cells were clearly involved as constituents of acute inflammatory lesions characterized by infiltration of arteries, occlusion of veins, and diapedesis through external epithelia of the mantle and gastrointestinal tract. Heavily contaminated sites (i.e. Raritan Bay, New Jersey) showed strong staining reactions in a large number of animals examined. Control sites such as Great Bay, New Jersey, showed much lighter reactions. Seasonal sampling in the New Jersey sites revealed the most intense involvement in the late summer with apparent decreasing staining intensities in the fall. Other species of bivalve mollusks (Mytilus edulis and Mercenaria mercenaria) only showed significant staining reactions for heavy metal in kidney tissues with no evidence that heavily contaminated sites had higher levels. These results constitute preliminary evidence of a cause-and-effect relationship between a heavy metal contaminant (most probably copper) and inflammatory lesions in the oyster.     

Continental terrace and Deep Plain offshore central California

Seismic-reflection profile investigations of the California continental terrace and Deep Plain, between 35°N and 39°N, support the hypothesis that the continental shelf and slope consist of alternating blocks of Franciscan and granitic-metamorphic basement overlain by varying thicknesses of younger sediments. North of 37°N, the seismic profiles confirm the distribution of turbidites shown by other workers. A significant proportion of the sediments on the middle and lower continental rise, south of 37°N, appears to be unrelated to the present Monterey deep-sea canyon system.Near 39°N the ridge which forms the topographic axis of the Delgada deep-sea fan consists of a thin cover of acoustically-transparent sediment unconformably overlying a thick sequence of turbidites; the southern part of this ridge is composed of well-defined short reflectors of highly variable dip. The ridge is incised by a steep-walled, flat-floored valley which follows a nearly straight course across its eastern flank. Among possible explanations for this pattern is uplift of the sea floor beneath the ridge.Our data and investigations of others indicate that acoustic basement north of 38°40N is at least 0.5 sec (two-way travel time) shoaler than it is south of Pioneer Ridge; when present, the ridge may represent as much as 0.5 sec additional basement relief. This structural pattern probably does not extend east of 127°40W, although the magnetic expression of the ridge persists to 127°W.Disappearance of the distinctive abyssal hills topography from west to east within the area of investigation usually can be attributed to burial by turbidites. Normal pelagic sediments form a veneer, rarely more than 0.15 sec thick, which conforms with the basement topography; some localities are devoid of discernible sediment.