98 research outputs found

    ΠšΡ€ΠΈΡ‚Π΅Ρ€ΠΈΠΈ ΠΈ срСдства развития ΠΏΡ€ΠΎΠ³Ρ€Π°ΠΌΠΌΠ½ΠΎΠ³ΠΎ обСспСчСния для модСлирования Π½Π΅Ρ„Ρ‚Π΅Π³Π°Π·ΠΎΠ²Ρ‹Ρ… мСстороТдСний

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    ΠžΠ±ΡΡƒΠΆΠ΄Π°ΡŽΡ‚ΡΡ Ρ€Π΅Π·ΡƒΠ»ΡŒΡ‚Π°Ρ‚Ρ‹ Π°Π½Π°Π»ΠΈΠ·Π° примСнимости ΠΈ эффСктивности ΠΏΡ€ΠΎΠ³Ρ€Π°ΠΌΠΌΠ½Ρ‹Ρ… систСм Π²Π΅Π΄ΡƒΡ‰ΠΈΡ… Π·Π°Ρ€ΡƒΠ±Π΅ΠΆΠ½Ρ‹Ρ… ΠΈ отСчСствСнных ΠΏΡ€ΠΎΠΈΠ·Π²ΠΎΠ΄ΠΈΡ‚Π΅Π»Π΅ΠΉ, ΠΊΡƒΠ»ΡŒΡ‚ΠΈΠ²ΠΈΡ€ΡƒΠ΅ΠΌΡ‹Ρ… Π½Π° Ρ€Ρ‹Π½ΠΊΠ΅ ΠΈΠ½Ρ„ΠΎΡ€ΠΌΠ°Ρ†ΠΈΠΎΠ½Π½Ρ‹Ρ… Ρ‚Π΅Ρ…Π½ΠΎΠ»ΠΎΠ³ΠΈΠΉ для модСлирования Π½Π΅Ρ„Ρ‚Π΅Π³Π°Π·ΠΎΠ²Ρ‹Ρ… мСстороТдСний. Π‘Ρ„ΠΎΡ€ΠΌΡƒΠ»ΠΈΡ€ΠΎΠ²Π°Π½Ρ‹ ΠΊΡ€ΠΈΡ‚Π΅Ρ€ΠΈΠΈ ΠΎΡ†Π΅Π½ΠΊΠΈ Π±Π°Π·ΠΎΠ²Ρ‹Ρ… ΠΏΡ€ΠΎΠ³Ρ€Π°ΠΌΠΌΠ½Ρ‹Ρ… систСм, ΠΊΠΎΡ‚ΠΎΡ€Ρ‹ΠΌΠΈ слСдуСт Ρ€ΡƒΠΊΠΎΠ²ΠΎΠ΄ΡΡ‚Π²ΠΎΠ²Π°Ρ‚ΡŒΡΡ ΠΏΡ€ΠΈ обосновании Π²Ρ‹Π±ΠΎΡ€Π°. Π”Π°Π½ΠΎ Ρ„ΠΎΡ€ΠΌΠ°Π»ΠΈΠ·ΠΎΠ²Π°Π½Π½ΠΎΠ΅ описаниС слоТных процСссов гСологичСского ΠΈ гидродинамичСского модСлирования Π½Π΅Ρ„Ρ‚Π΅Π³Π°Π·ΠΎΠ²Ρ‹Ρ… мСстороТдСний с использованиСм Ρ†ΠΈΡ„Ρ€ΠΎΠ²Ρ‹Ρ… 3D-ΠΌΠΎΠ΄Π΅Π»Π΅ΠΉ ΠΈ ΠΏΠΎΠ΄Π΄Π΅Ρ€ΠΆΠΈΠ²Π°ΡŽΡ‰ΠΈΡ… ΠΈΡ… ΠΏΡ€ΠΎΠ³Ρ€Π°ΠΌΠΌΠ½Ρ‹Ρ… систСм

    Meeresspiegelschwankungen und ihre geologische Überlieferung im Karbonatsystem

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    The dependency between carbonate sediment production on a carbonate platform and its relation to sea-level changes is discusses here. The topography of the upper slope plays an important role in determining the way in which sedimentation continues during lowstands in sea level. The mineralogy and composition of sediments produced on the platform can clearly be related to those found in sediments deposited in the adjacent basin. Two examples from the Recent are described: (1) Sanganeb Atoll (Red Sea), and (2) Pedro Bank (caribbean). The applicability of the "highstand shedding" principle is shown for ancient carbonate platforms

    Анализ ΠΈ интСрпрСтация гидродинамичСских исслСдований для Π΄Π²ΡƒΡ…Ρ„Π°Π·Π½ΠΎΠ³ΠΎ ΠΏΠΎΡ‚ΠΎΠΊΠ° (Π²ΠΎΠ΄Π°-Π½Π΅Ρ„Ρ‚ΡŒ)

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    ΠŸΠΎΠΊΠ°Π·Π°Π½Ρ‹ ΠΏΡ€ΠΎΠ±Π»Π΅ΠΌΡ‹, Π²ΠΎΠ·Π½ΠΈΠΊΠ°ΡŽΡ‰ΠΈΠ΅ ΠΏΡ€ΠΈ ΠΈΠ½Ρ‚Π΅Ρ€ΠΏΡ€Π΅Ρ‚Π°Ρ†ΠΈΠΈ ΠΈ Π°Π½Π°Π»ΠΈΠ·Π΅ Π΄Π°Π½Π½Ρ‹Ρ… гидродинамичСских исслСдований, ΠΏΡ€ΠΎΠ²Π΅Π΄Π΅Π½Π½Ρ‹Ρ… Π½Π° скваТинах с ΠΎΠ±Π²ΠΎΠ΄Π½Π΅Π½Π½ΠΎΡΡ‚ΡŒΡŽ, ΠΎΡ‚Π»ΠΈΡ‡Π½ΠΎΠΉ ΠΎΡ‚ нуля. Π Π°Π·ΠΎΠ±Ρ€Π°Π½Ρ‹ прСимущСства ΠΈ нСдостатки примСняСмых ΠΌΠ΅Ρ‚ΠΎΠ΄ΠΎΠ² ΠΈΠ½Ρ‚Π΅Ρ€ΠΏΡ€Π΅Ρ‚Π°Ρ†ΠΈΠΈ ΠΈ Π°Π½Π°Π»ΠΈΠ·Π°. ΠŸΡ€Π΅Π΄ΡΡ‚Π°Π²Π»Π΅Π½ Π½ΠΎΠ²Ρ‹ΠΉ ΠΌΠ΅Ρ‚ΠΎΠ΄ Π½ΠΎΡ€ΠΌΠ°Π»ΠΈΠ·Π°Ρ†ΠΈΠΈ подвиТности для Π°Π½Π°Π»ΠΈΠ·Π° Ρ€Π΅Π·ΡƒΠ»ΡŒΡ‚Π°Ρ‚ΠΎΠ² гидродинамичСских исслСдований скваТин

    The surface energy balance during foehn events at Joyce Glacier, McMurdo Dry Valleys, Antarctica

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    The McMurdo Dry Valleys (MDV) are a polar desert, where glacial melt is the main source of water to streams and the ecosystem. Summer air temperatures are typically close to zero, and therefore foehn events can have a large impact on the meltwater production. A 14-month record of automatic weather station (AWS) data on Joyce Glacier is used to force a 1D surface energy balance model to study the impact of foehn events on the energy balance. AWS data and output of the Antarctic Mesoscale Prediction System (AMPS) on a 1.7 km grid are used to detect foehn events at the AWS site. Foehn events at Joyce Glacier occur under the presence of cyclones over the Ross Sea. The location of Joyce Glacier on the leeward side of the Royal Society Range during these synoptic events causes foehn warming through isentropic drawdown. This mechanism differs from the foehn warming through gap flow that was earlier found for other regions in the MDV and highlights the complex interaction of synoptic flow with local topography of the MDV. Shortwave radiation is the primary control on melt at Joyce Glacier, and melt often occurs with subzero air temperatures. During foehn events, melt rates are enhanced, contributing to 23 % of the total annual melt. Foehn winds cause a switch from a diurnal stability regime in the atmospheric surface layer to a continuous energy input from sensible heat flux throughout the day. The sensible heating during foehn, through an increase in turbulent mixing resulting from gustier and warmer wind conditions, is largely compensated for by extra heat losses through sublimation. Melt rates are enhanced through an additional energy surplus from a reduced albedo during foehn.</p

    Are spherulitic lacustrine carbonates an expression of large-scale mineral carbonation? : A case study from the East Kirkton Limestone, Scotland

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    BP Exploration Co. is thanked for funding, and particularly the Carbonate Team for supporting this research and for fruitful discussions. West Lothian Council and Scottish Natural Heritage are thanked for allowing access and permission for sampling the site. The Core Store Team at BGS Keyworth is particularly acknowledged for their assistance. Mark Anderson, Tony Sinclair (University of Hull), and Bouk Lacet (VU University Amsterdam) are thanked for technical support. Anne Kelly (SUERC) for carrying out the Strontium Isotope analyses. Mark Tyrer is thanked for his advice on PHREEQC modelling.Peer reviewedPostprin

    Synchroneity of major late Neogene sea level fluctuations and paleoceanographically controlled changes as recorded by two carbonate platforms

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    Shallow-water carbonate systems are reliable recorders of sea level fluctuations and changes in ambient seawater conditions. Drilling results from Ocean Drilling Program (ODP) Legs 133 and 166 indicate that the timing of late Neogene sedimentary breaks triggered by sea level lowerings is synchronous in the sedimentary successions of the Queensland Plateau and the Great Bahama Bank. This synchrony indicates that these sea level changes were eustatic in origin. The carbonate platforms were also affected by contemporary, paleoceanographically controlled fluctuations in carbonate production. Paleoceanographic changes are recorded at 10.7, 3.6, and 1.7–2.0 Ma. At the Queensland Plateau, sea surface temperature shifts are documented by shifts from tropical to temperate carbonates (10.7 Ma) and vice versa (3.6 Ma); the modern tropical platform was established at 2.0–1.8 Ma. At Great Bahama Bank, changes were registered in compositional variations of platform-derived sediment, such as major occurrence of peloids (3.6 Ma) and higher rates of neritic carbonate input (1.7 Ma). The synchroneity of these changes attests to the far-field effects of modifications in the oceanographic circulation on shallow-water, low-latitude carbonate production

    Holocene Atlantic climate variations deduced from carbonate peri-platform sediments (leeward margin, Great Bahama Bank)

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    A marine sediment core from the leeward margin of Great Bahama Bank (GBB) was subjected to a multiproxy study. The aragonite dominated core MD992201 comprises the past 7230 years in a decadal time resolution and shows sedimentation rates of up to 13.8 m/kyr. Aragonite mass accumulation rates, age differences between planktonic foraminifera and aragonite sediments, and temperature distribution are used to deduce changes in aragonite production rates and paleocurrent strengths. Aragonite precipitation rates on GBB are controlled by exchange of carbonate ions and CO2 loss due to temperature-salinity conditions and biological activity, and these are dependent on the current strength. Paleocurrent strengths on GBB show high current velocities during the periods 6000–5100 years BP, 3500–2700 years BP, and 1600–700 years BP; lower current speeds existed during the time intervals 5100–3500 years BP, 2700–1600 years BP, and 700–100 years BP. Bahamian surface currents are directly linked to the North Atlantic atmospheric circulation, and thus periods with high (low) current speeds are proposed to be phases of strong (weak) atmospheric circulation

    Sub-Milankovitch cycles in periplatform carbonates from the early Pliocene Great Bahama Bank

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    High-resolution bulk sediment (magnetic susceptibility and aragonite content) and Ξ΄18O records from two different planktonic foraminifera species were analyzed in an early Pliocene core interval from the Straits of Florida (Ocean Drilling Program site 1006). The Ξ΄18O record of the shallow-dwelling foraminifera G. sacculifer and the aragonite content are dominated by sub-Milankovitch variability. In contrast, magnetic susceptibility and the Ξ΄18O record of the deeper-dwelling foraminifera G. menardii show precession cycles. The relationship between the aragonite and the paleoproxy data suggests that the export of sediment from the adjacent Great Bahama Bank was triggered directly by atmospheric processes rather than by sea level change. We propose a climate mechanism that bears similarities with the semiannual cycle component of eastern equatorial Pacific sea surface temperatures under present-day conditions

    Carbonate delta drift: a new sediment drift type

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    Based on high-resolution reflection seismic and core data from IODP Expedition 359 we present a new channel-related drift type attached to a carbonate platform slope, which we termed delta drift. Like a river delta, it is comprised of several stacked lobes and connected to a point source. The delta drifts were deposited at the exit of two gateways that connect the Inner Sea of the Maldives carbonate platform with the open ocean. The channels served as conduits focusing and accelerating the water flow; Entrained material was deposited at their mouth where the flows relaxed. The lobe-shaped calcareous sediment drifts must have formed under persistent water through flow. Sediment supply was relatively high and continuous, resulting in an average sedimentation rate of 17 cm kaβˆ’1. The two delta drifts occupy 342 and 384 km2, respectively; with a depositional relief of approximately 500 m. They have a sigmoidal clinoform reflection pattern with a particular convex upward bending of the foresets. In the Maldives the drift onset marks the transition from a sea-level controlled to a progressively current dominated depositional regime. This major event occurred in the Serravallian about 13 Ma ago, leading to the partial drowning of the carbonate platform and the creation of shallow seaways. The initial bank-enclosed topography resembles an β€œempty bucket” geometry which is rapidly filled by the drift sediments that aggrade and prograde into the basin. Thereby the depositional environment of the delta drifts changes from deep water (>500) to shallow-water conditions at their topsets, indicated by the overall coarsening upward trend in grain size and the presence of shallow water large benthic foraminifers at their top
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