Biostratigraphy, Age, and Paleoenvironment of the Pliocene Beaufort Formation on Meighen Island, Canadian Arctic Archipelago

ABSTRACT Meighen Island, in the Canadian Arctic Archipelago, is one of the most important localities for study of the late Neogene Beaufort Formation because of the presence of marine sediments interbedded with terrestrial fossiliferous sands. The stratigraphic succession, fossils from the marine beds, correlation with reconstructions of sea level, and paleomagnetic data from the Bjaere Bay region of the island suggest that the Beaufort Formation on Meighen Island was likely deposited either at 3.2–2.9 Ma or during two intervals at ca. 4.5 Ma and 3.4 Ma. The exposed Beaufort Formation on Meighen Island probably encompasses at least one warm interval and eustatic sea-level highstand of the Pliocene. Fossils of plants and arthropods are abundant in the alluvial sands exposed in the Bjaere Bay region. The lower part of the sequence (Unit A), beneath the muddy marine sequence (Unit B), contains plant taxa that have not been seen above the marine beds. Sediments below the marine beds are dominated more by fossils of trees, whereas the organic debris from above marine beds contains many fossils of plants, insects, and mites characteristic of open treeless sites. Regional tree line probably occurred on Meighen Island during deposition of the upper sediments, which implies a mean July climate at least 9 °C warmer than at present. When the marine sediments were deposited, nearshore water temperatures probably did not fall below 0 °C; hence, the Arctic Ocean probably lacked perennial ice cover. This confirms recent modeling experiments exploring the causes of Arctic amplification of temperature that have found the removal of sea ice to be a key factor in resolving previous proxy-model mismatches.

Active sediment creep deformation on a deep-sea terrace in the Japan Trench

Eighty-six new acoustic survey lines along and across the Japan Trench revealed active sediment creep deformation on a deep-sea terrace at water depths of 400–1200 m in an area of arcuate-shaped depressions that are probably associated with tectonic erosion. The most active region of creep is located on the top at the surface of the depression south of 38° N. The area of creep deformation is characterized by arcuate-shaped topographic lineaments with active folds and active normal faults stepping down trenchward. In contrast to the southern region, normal faults at the top of the depression north of 38° N cut a sedimentary sequence (Unit 1) that is acoustically transparent with continuous weak reflectors, and this is covered by the undeformed layered sediment sequence of Unit 2. Unit 2 corresponds to the period of rising sea level that extended from the latest Pleistocene to the early Holocene (14–6 ka). Thus, creep is ongoing at the top of the depression south of 38° N in the surface layer, whereas it stopped north of the depression between 14 and 6 ka. These observations might indicate that the active region jumped from north to south due to probably retrogressive sliding.

Sedimentary Facies of the First Member of Qingshankou-Formation in Late Cretaceous Songliao Basin of Daqing Oilfield China

According to core, logging and seismic data, using tectonic-stratigraphic and sequence stratigraphic analysise theories in Qingshankou Formation of division and comparison, and the sequence boundary and sequence unit to be optimized, in order to carry out seismic deposition. By determining the levels of sequence interface on seismic, logging and faces reflecting characteristics of the study area to build sequence interface identifier. In the course of practical work, identified the continental basin of the more common of the one to three levels of sequence interface, system interface and the parasequence set interface. In Songliao Basin, second-order sequences often corresponding to the tectonic evolution of the basin episodic stage, and in each period of prototype basin internal episodic tectonic extension or episodic of tectonic inversion is consistent, in Qingshankou Formation in the development of one second-order sequence boundary SB11 (T11), three third-order sequence boundary, there are SB12 (T12), SB13 (T13) and SB2 (T2), seven forth-order sequence boundary. In the plane, using the data of 256 wells, analysis of the distribution characteristics of the sedimentary facies of the first member of Qingshankou-Formation.

INVENTORY DECISIONS WITH DECREASING PURCHASING COSTS

Costs of many items drop systematically throughout their life-cycles, due to advances in technology and competition. Motivated by the management of service parts for some high-tech products, this paper studies inventory decisions for such items. In a periodic review setting with stochastic demand, we model the purchasing costs of successive periods as a stochastic and decreasing sequence. Unit selling price of the item is determined as some mark-up of the purchasing cost and, hence, will change over time as well. We consider two specific mark-up models: (1) purchasing cost plus constant-dollar-amount mark-up, and (2) purchasing cost plus constant-percentage mark-up. To maximize the total discounted expected profit, we derive conditions under which myopic policies are optimal for the systems.

Effects of the Sequence and Pattern Unit of Bright Start on Seriational and Math Problem Solving among Kindergarten Children of Ethiopian Immigrants to Israel

In order to investigate the effects of cognitive early education on the seriational performance and learning effectiveness of transcultural children, 20 young Ethiopian children whose families had immigrated to Israel were given two tests of seriational thinking before and after they received mediational instruction in the Pattern and Sequence unit of Bright Start: Cognitive Curriculum for Young Children. 20 children of the same age, gender distribution, and family background had a control (non-mediational) activity. The control children performed initially at a higher level than did the cognitive education children, but the latter group closed that gap and surpassed the performance of the control children following their Bright Start experience. The authors concluded that there was evidence of cultural difference rather than cultural deprivation in this transcultural group, that their performance in seriational problem solving could be enhanced by cognitive early education, and that there was also evidence of intermediate transfer of their training in seriation.

Fossil plants from the Viséan of East Kirkton, West Lothian, Scotland

ABSTRACTPlant fossils are a common and important element in the East Kirkton biota of Brigantian (late Viséan age). The most important taxa are preserved as compressions or anatomically preserved as permineralisations. The basis of the quantitative study of the flora and the distribution of individual plant species was the trenched section excavated for the East Kirkton Project. The largest diversity of compressions have been recorded from loose blocks. In the trenched section, the uppermost ashes contain only lycopsid compressions including Stigmaria. Nodules in the underlying shales yield mainly lycopsid leaf and sporophyll compressions. The uppermost limestones (Units 39-52) contain drifted fragments of pteridosperm fronds mainly Sphenopteridium crassum, S. pachyrrhachis, Spathulopteris obovata and Adiantites antiquus. Permineralised Lyginorachis spp. occur at this level. Large permineralised woody gymnosperm axes have been found loose (including Pitus, 50 cm in diameter). Permineralised axes, mainly reworked, including the gymnosperms Bilignea, Eristophyton, Stanwoodia and possibly Protopitys, have been found in Units 72-88. Poorly preserved permineralised lycopsids are rare, but include Lepidophloios. Loose chert blocks contain root mats of permineralised Stigmaria, together with Lepidocarpon, the sphenopsid Archaeocalamites and the fern Botryopteris. Similar material is found in Unit 83 of the Limestone sequence. Unit 82, the black shale containing many of the articulated vertebrates, contains predominantly pteridosperm frond and pinnule material including Spathulopteris obovata. The distinctive changes in the flora from the base to the top of the trenched sequence reflect mainly ecological and taphonomic controls upon plant distribution and preservation. Evidence suggests a close relationship between climate, fire, erosion, deposition and vegetation type through the sequence and a climatic change, from a drier to a wetter environment, is suggested at the top of the East Kirkton Limestone sequence.

A Point-on-Wave Switching-Sequence Unit for Power System Studies

The design and operation of a unit based on integrated circuit counters is described. Single or polyphase switching control is derived from a single phase signal of any frequency. The pulses generated can be used to build up complex controlled sequential switching operations and for triggering associated equipment.