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Artículos de revistas sobre el tema "Paleoreconstruction"

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Publicado: 10 de marzo de 2023

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1

Neplyukhina, A. A. "Diatoms of the Aleutian Islands (Alaska, USA) in the Holocene". Limnology and Freshwater Biology, n.º 4 (2022): 1509–11. http://dx.doi.org/10.31951/2658-3518-2022-a-4-1509.

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Abstract. Here presented a short overview of paleoreconstruction works started since 2018 for the Aleutian Islands region. Material is from four Aleutian Islands that represented by peat deposits and modern waterbodies samples are studied. Modern and fossil diatom communities of these islands are described, diatom analyses and paleoreconstructions are performed.
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2

Ts Pintaeva, E. "Lipid biomarkers in paleoreconstruction of lake sedimentogenesis". IOP Conference Series: Earth and Environmental Science 320 (29 de agosto de 2019): 012016. http://dx.doi.org/10.1088/1755-1315/320/1/012016.

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3

Maznev, S. V. "The Anthropocene evolution of the Aral Sea ice gouging derived from the bottom topography". Limnology and Freshwater Biology, n.º 4 (2022): 1495–96. http://dx.doi.org/10.31951/2658-3518-2022-a-4-1495.

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Abstract. Ice gouging landforms on the exposed bottom of the Aral Sea give a possibility to get a profound knowledge about processes of the ice-bottom interaction during the level fall. We analyzed ice scours in the different parts of the Aral Sea using geomorphological and remote methods and evaluated the paleoreconstruction of ice gouging processes in the Anthropocene.
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4

Castellano, E., M. Severi, R. Traversi, S. Becagli y R. Udisti. "Paleoreconstruction of volcanic history inferred from glacio-chemical ice core analyses". PAGES news 13, n.º 3 (noviembre de 2005): 3–5. http://dx.doi.org/10.22498/pages.13.3.3.

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5

Unger, A. V., A. M. Nikishin, M. A. Kuzlyapina y A. P. Afanasenkov. "History of the inversion megaswells of the Yenisei-Khatanga basin development". Moscow University Bulletin. Series 4. Geology, n.º 2 (28 de abril de 2017): 8–15. http://dx.doi.org/10.33623/0579-9406-2017-2-8-15.

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Paper presents description of Balakhninsky and Rassohinsky swells, which were located in the central part of the Yenisei-Khatanga Basin by seismic and drilling data, and the results of its geological structure comparative analysis. History of swells formation discussed in de- tails, including rift initiation in the Late Permian-Early Triassic time and stages of inversion structures growth intensification in the Middle Triassic, Late Jurassic, Early Cretaceous and Cenozoic time. Asynchronous development of these structures established on the base of paleoreconstruction analysis.
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6

Nikitina, E. y E. Pintaeva. "A new approach to paleoreconstruction of Gusinoe Lake sediments: lipid biomarker analysis". Limnology and Freshwater Biology, n.º 4 (2020): 573–74. http://dx.doi.org/10.31951/2658-3518-2020-a-4-573.

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7

Macreadie, Peter I., Katie Allen, Brendan P. Kelaher, Peter J. Ralph y Charles G. Skilbeck. "Paleoreconstruction of estuarine sediments reveal human‐induced weakening of coastal carbon sinks". Global Change Biology 18, n.º 3 (23 de noviembre de 2011): 891–901. http://dx.doi.org/10.1111/j.1365-2486.2011.02582.x.

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8

Baskakova, G. V. y A. M. Nikishin. "Geological history of the Kerch-Taman area based on the reconstruction of the regional balanced section". Moscow University Bulletin. Series 4. Geology, n.º 4 (28 de agosto de 2018): 23–29. http://dx.doi.org/10.33623/0579-9406-2018-4-23-29.

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The geological framework and tectonics of the Eastern Black Sea region is characterized through balancing a geological cross-section and paleoreconstruction during the Paleogene-Neogene period. Studied area includes the Kerch-Taman Trough, the Anapa Swell (the continuation of the immersed part of the Greater Caucasus Orogen), the Tuapse trough and the Shatsky Swell. The paper is mainly focused on the Russian shelf zone of the Black sea. The results are important for understanding of the trap formation time and the hydrocarbon deposits preservation in the Russian sector of the Black sea shelf.
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9

Mißbach, H., J. P. Duda, N. K. Lünsdorf, B. C. Schmidt y V. Thiel. "Testing the preservation of biomarkers during experimental maturation of an immature kerogen". International Journal of Astrobiology 15, n.º 3 (4 de abril de 2016): 165–75. http://dx.doi.org/10.1017/s1473550416000069.

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AbstractLipid biomarkers have been extensively applied for tracing organisms and evolutionary processes through Earth's history. They have become especially important for the reconstruction of early life on Earth and, potentially, for the detection of life in the extraterrestrial realm. However, it is not always clear how exactly biomarkers reflect a paleoecosystem as their preservation may be influenced by increasing temperatures (T) and pressures (P) during burial. While a number of biomarker indices reflecting thermal maturity have been established, it is often less well constrained to which extent biomarker ratios used for paleoreconstruction are compromised by T and P processes. In this study we conducted hydrous pyrolysis of Green River Shale (GRS) kerogen in gold capsules for 2–2400 h at 300°C to assess the maturation behaviour of several compounds used as life tracers and for the reconstruction of paleoenvironments (n-alkanes, pristane, phytane, gammacerane, steranes, hopanes and cheilanthanes). Lignite samples were maturated in parallel with the GRS kerogen to obtain exact vitrinite reflectance data at every sampling point. Our experiment confirms the applicability of biomarker-based indices and ratios as maturity indicators (e.g. total cheilanthanes/hopanes ratio; sterane and hopane isomerization indices). However, several biomarker ratios that are commonly used for paleoreconstructions (e.g. pristane/phytane, pristane/n-C17, phytane/n-C18 and total steranes/hopanes) were considerably affected by differences in the thermal degradation behaviour of the respective compounds. Short-term experiments (48 h) performed at 400°C also revealed that biomarkers >C15 (especially steranes and hopanes) and ‘biological’ chain length preferences for n-alkanes are vanished at a vitrinite reflectance between 1.38 and 1.83% RO. Our data highlight that ‘thermal taphonomy’ effects have to be carefully considered in the interpretation of biomarkers in ancient rocks and, potentially, extraterrestrial materials.
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10

Tessier, Bernadette. "Upper intertidal rhythmites in the Mont-Saint-Michel Bay (NW France): Perspectives for paleoreconstruction". Marine Geology 110, n.º 3-4 (marzo de 1993): 355–67. http://dx.doi.org/10.1016/0025-3227(93)90093-b.

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11

Hoshmand, Ali Mustafa. "Construction of a Fracture Network Model Basedon Paleoreconstruction Calculation for Estimation of High­Permeable Intervals". Oil and Gas Technologies 123, n.º 4 (2019): 33–38. http://dx.doi.org/10.32935/1815-2600-2019-123-4-33-38.

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12

Subetto, D. A. y A. P. Fedotov. "Paleoreconstruction of environment of Northern Eurasia during the Pleistocene-Holocene inferred from lake sediment proxies". Limnology and Freshwater Biology, n.º 4 (2022): 1376–77. http://dx.doi.org/10.31951/2658-3518-2022-a-4-1376.

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13

Levitskiy, V. I., L. Z. Reznitsky y I. V. Levitskiy. "Geochemistry of carbonate rocks in early Precambrian and phanerozoic metamorphic complexes of East Siberia, north-west of Russia, Pamir". Геохимия 64, n.º 4 (5 de mayo de 2019): 409–26. http://dx.doi.org/10.31857/s0016-7525644409-426.

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Geochemical study of carbonate rocks of Early-Precambrian and Phanerozoic metamorphic Complexes was carried out and their differences were revealed. Precambrian marbles and calciphyres studied in the Оnot Greenstone Belt, Kitoy and Sharyzhalgay granulitic Complexes Presayan uplift, Yenisei Series of the Angara-Kan Protrusion of the Siberian craton, the Belomorian and Lapland Complexes, North of the Pechenga Structure, Sortavala Suite of the Fennoscandian shield, Wakhan Complex of the Badakhshan Array; Phanerozoic – in Olkhon, Slyudyanka, Svyato nossky Complexes of the Baikal region, Boxon Series and Irkutnu Suite of the Eastern Sayan, Derbinsky Complex and Alchadur Suite of the Prisayan, Judin Suite and Panimba-Rybinsk Zone of the Yenisei Ridge, Muzkol Complex of the Eastern Pamirs. Precambrian carbonate rocks are enriched with Fe, Mn and depleted Sr, Ba in comparison with Phanerozoic rocks at a close low level of REE content. The Archean enrichment of Fe, Mn protoliths of marbles and calcifers is due to the dominance of basic and ultrabasic rocks in the feeding provinces. In the Paleoproterozoic, compared with the Phanerozoic, the proportion of Fe, Mn in carbonate rocks decreased, and Al, K, Ba, Sr have increased due to participation in occurrence their protoliths of the granite-metamorphic layer of the Earth. The distribution of petrogenic and rare elements in marbles and calcifirs is determined by the forms of their location: 1) in the isomorphic series of Ca-Mg carbonates with admixture of Fe, Mn, Ba, Sr, REE; 2) the presence of minerals Na, K, Ba, Sr in marbles; 3) location of thin (in marbles) and large (calcifications) fractions of minerals with iron, Mn Al, Ti, Zr, Cr, V, Ni, S. Performed paleoreconstruction behavior of REE in carbonate rocks in the Archean and Early-Paleoproterozoic dominated intracratonic shallow sea. Open oceans appeared at the turn of 2–1.9 billion years, but widespread development of carbonate rocks were in the Meso-Neoproterozoic and Phanerozoic. The revealed features are the basis of age-related paleoreconstructions of protoliths according to petrogeochemical characteristics of carbonate rocks of Precambrian and Phanerozoic metamorphic complexes.
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14

Nemchenko, E. I., O. A. Lipatnikova, L. L. Demina, M. D. Kravchishina y T. N. Lubkova. "Distribution of elements in the vertical cut of bottom sediments of the Black sea". Moscow University Bulletin. Series 4. Geology, n.º 1 (28 de febrero de 2020): 60–68. http://dx.doi.org/10.33623/0579-9406-2020-1-60-68.

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The trace element composition of the vertical section of the Black Sea bottom sediments was studied. Based on the calculated enrichment factors relative to the average composition of the earth’s crust, it was shown that a lithogenic source is predominant for most trace elements. Significant enrichment was obtained for Ca and Sr (due to bioaccumulation) and for S, As and Mo (as a result of hydrogen sulfide contamination processes and the influence of mud volcanoes). A specific conditions of sedimentation were estimated based on the elements’ ratios which indicate: a presence of exhalation components in the deposits (Fe+Mn/Ti), a range of transport of terrigenous material (Ti/Zr) were estimated; paleoreconstruction of salinity (Corg/S), as well as redox conditions in the bottom water layer (Mn/Fe, Mo/Mn, V/(V+Ni), V/Mn).
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15

Pastukhov, Alexander, Tatiana Marchenko-Vagapova, Sergey Loiko y Dmitry Kaverin. "Vulnerability of the Ancient Peat Plateaus in Western Siberia". Plants 10, n.º 12 (19 de diciembre de 2021): 2813. http://dx.doi.org/10.3390/plants10122813.

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Based on the data of the plant macrofossil and palynological composition of the peat deposits, the evolution and current state of polygonal peatlands were analyzed at the southern limit of continuous permafrost in the Pur-Taz interfluve. Paleoreconstruction shows that peat accumulation began in the Early Holocene, about 9814 cal. year BP, in the Late Pre-Boreal (PB-2), at a rate of 1 to 1.5 mm year−1. Intensive peat accumulation continued in the Boreal and early Atlantic. The geocryological complex of polygonal peatlands has remained a stable bog system despite the predicted warming and increasing humidity. However, a rather rapid upper permafrost degradation and irreversible changes in the bog systems of polygonal peatlands occur with anthropogenic disturbances, in particular, a change in the natural hydrological regime under construction of linear objects.
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16

Tokarev, I. V., A. A. Zubkov, V. G. Rumynin, S. P. Pozdnyakov, V. A. Polyakov y V. Yu Kuznetsov. "Assessment of the long-term safety of radioactive waste disposal: 1. Paleoreconstruction of groundwater formation conditions". Water Resources 36, n.º 2 (marzo de 2009): 206–13. http://dx.doi.org/10.1134/s0097807809020092.

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17

Grachev, Alexi M. y Jeffrey P. Severinghaus. "Determining the Thermal Diffusion Factor for40Ar/36Ar in Air To Aid Paleoreconstruction of Abrupt Climate Change". Journal of Physical Chemistry A 107, n.º 23 (junio de 2003): 4636–42. http://dx.doi.org/10.1021/jp027817u.

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18

I.S., Kirichenko, LAZAREVA E. V., ZHMODIK S. M., DOBREZOV N. L., BELYANIN D. K. y MIROSHNICHENKO L. V. "Modern mineral formation in the thermal lake Fumarolnoe (Uson caldera, Kamchatka) is the key to paleoreconstruction". Zapiski RMO (Proceedings of the Russian Mineralogical Society) 148, n.º 1 (2019): 3–15. http://dx.doi.org/10.30695/zrmo/2019.1481.00.

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19

Kirichenko, I. S., E. V. Lazareva, S. M. Zhmodik, N. L. Dobrezov, D. K. Belyanin y L. V. Miroshnichenko. "Modern Mineral Formation in the Thermal Lake Fumarolnoe (Uzon Caldera, Kamchatka) as a Key to Paleoreconstruction". Geology of Ore Deposits 61, n.º 8 (diciembre de 2019): 747–55. http://dx.doi.org/10.1134/s1075701519080063.

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20

Pintaeva, E. Ts, L. D. Radnaeva, E. P. Nikitina, V. G. Shiretorova y A. K. Tulokhonov. "Lipid Biomarkers of Bottom Sediments in Gusinoe Lake (Lake Baikal Basin) as Indicators for Lake Sedimentogenesis Paleoreconstruction". Doklady Earth Sciences 491, n.º 1 (marzo de 2020): 168–70. http://dx.doi.org/10.1134/s1028334x20030149.

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21

Reavie, Euan D., Adam J. Heathcote y Victoria L. Shaw Chraïbi. "Laurentian Great Lakes Phytoplankton and Their Water Quality Characteristics, Including a Diatom-Based Model for Paleoreconstruction of Phosphorus". PLoS ONE 9, n.º 8 (8 de agosto de 2014): e104705. http://dx.doi.org/10.1371/journal.pone.0104705.

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22

Szopa, Krzysztof, Sylwia Skreczko, David Chew, Tomasz Krzykawski y Artur Szymczyk. "Multi-Tool (LA-ICPMS, EMPA and XRD) Investigation on Heavy Minerals from Selected Holocene Peat-Bog Deposits from the Upper Vistula River Valley, Poland". Minerals 10, n.º 1 (20 de diciembre de 2019): 9. http://dx.doi.org/10.3390/min10010009.

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Peat sediments represent important environmental and climatic archives, as well as recording information on the processes affecting the formation of these deposits; combined these data can be used for paleoreconstruction of peat-bogs. In this paper we characterize heavy mineral-rich sandy layers from two peat-bog sites in Mizerów and Strumień (Poland). In both cases, the most common identified mineral suite is: epidote, staurolite, tourmaline (dravite and schörl), garnet, spinel, Al2SiO5 polymorphs (sillimanite, kyanite, andalusite), amphibole (mainly hornblende), pyroxene (e.g., richterite, diopside), perovskite, topaz, cordierite, apatite, monazite, chromite, ilmenite, chlorite, iron oxides, rutile and siderite. This mineral suite is characteristic of a metamorphic aureole surrounding a magmatic body. Pyrite is likely authigenic in origin. Apatite and monazite were employed for U-Pb and CHIME dating, respectively. Based on the U-Pb age information composition and textural features of selected minerals, different provenance areas were indicated: the Tatra Massif, the Bohemian Massif, and the Silesian Basin area. Transport of the investigated mineral phases was linked to development of both the Odra (praOdra) and the Vistula valleys.
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23

Wojewódka, Marta y Dario Hruševar. "The role of paleolimnology in climate and environment reconstruction and lake restoration in light of research on selected bioindicators". Holistic approach to environment 10, n.º 1 (27 de febrero de 2020): 16–28. http://dx.doi.org/10.33765/thate.10.1.3.

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Paleolimnologists and ecologists study biotic and abiotic variables to track long-term and short-term environment changes. Microscopic invertebrates, phytoplankton of freshwater ecosystems, and pollen grains have been extensively studied during the last decades. Surveys of modern and fossil biota composition might provide information about past changes caused by climate alteration and human activity. Furthermore, research on the modern population of these biological proxies may be utilized to assess environmental quality and restoration measures. This paper synthesizes knowledge of the use of selected microscopic invertebrates (Cladocera, Copepoda, Ostracoda, Rotifera), phytoplankton, and pollen grains for the aforementioned issues. This review shows that the ability of these biological proxies to indicate environment changes is versatile. Some of them may be utilized to track long-term changes of temperature (pollen) or pH (Diatomeae). Others are useful to reconstruct paleosalinity (Ostracoda) or conductivity (Ostracoda, Diatomeae), while the utilization of Rotifera and Copepoda in paleoreconstruction, due to the very poor preservation of the remains, is very limited, although these fauna are very useful for assessing modern water quality. Larger species of Cladocera are significant for lake restoration
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24

Rybak, O. O. y P. Huybrechts. "MATHEMATICAL MODELING OF ICE FLOW IN QUEEN MAUD LAND, ANTARCTICA, AND ITS APPLICATION TO THE LATE QUATERNARY CLIMATIC PALEORECONSTRUCTION". Ice and Snow 52, n.º 3 (14 de noviembre de 2015): 5. http://dx.doi.org/10.15356/2076-6734-2012-4-5-16.

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25

Rouse, Glenn E. "Palynological dating and paleoreconstruction of three gold and silver orebodies in the western Cordillera of Canada, United States, and Mexico". Ore Geology Reviews 5, n.º 5-6 (octubre de 1990): 389–98. http://dx.doi.org/10.1016/0169-1368(90)90043-m.

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26

Sherstyukov, M. P., A.-G. G. Kerimov, A. G. Saltanova, E. V. Sokolenko y E. G. Kerimova. "The paleoreconstruction of sedimentation conditions at Beshpagirskoe deposit of the Stavropol Krai based on the results of pebble morphology investigation". IOP Conference Series: Earth and Environmental Science 579 (5 de noviembre de 2020): 012023. http://dx.doi.org/10.1088/1755-1315/579/1/012023.

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27

Serdyuk, N. V. "Paleoreconstruction of Pleistocene environments of human habitats in the Late Pleistocene and Holocene near the Charyshskii Naves cave, Central Altai, Russia". Paleontological Journal 40, n.º 4 (agosto de 2006): S501—S507. http://dx.doi.org/10.1134/s0031030106100108.

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28

Fuenlabrada, José Manuel, Ricardo Arenas, Sonia Sánchez Martínez, Rubén Díez Fernández, Agustín P. Pieren, M. Francisco Pereira, Martim Chichorro y José B. Silva. "Geochemical and isotopic (Sm Nd) provenance of Ediacaran-Cambrian metasedimentary series from the Iberian Massif. Paleoreconstruction of the North Gondwana margin". Earth-Science Reviews 201 (febrero de 2020): 103079. http://dx.doi.org/10.1016/j.earscirev.2019.103079.

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29

Wilmking, M. y J. Singh. "Eliminating the "divergence problem" at Alaska's northern treeline". Climate of the Past Discussions 4, n.º 3 (11 de junio de 2008): 741–59. http://dx.doi.org/10.5194/cpd-4-741-2008.

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Abstract. Recently, an increasing off-set between tree-ring based temperature reconstructions and measured temperatures at high latitudes has been reported, the so called "divergence problem" (here "divergence effect"). This "divergence effect" seriously questions the validity of tree-ring based climate reconstructions, since it seems to violate the assumption of a stable response of trees to changing climate over time. In this study we eliminated the "divergence effect" in northern Alaska by careful selection of individual trees with consistently significant positive relationships with climate (17% of sample) and successfully attempted a divergence-free climate reconstruction using this sub-set. However, the majority of trees (83%) did not adhere to the uniformitarian principle as usually applied in dendroclimatology. Our results thus support the notion, that factors acting on an individual tree basis are the primary causes for the "divergence effect" (at least in northern Alaska). Neither different detrending methods nor factors acting on larger scales such as global dimming or an increase in UV-B radiation could explain our results. Our results also highlight the necessity to adapt the methods of paleoreconstruction using tree rings to account for non-stable climate growth relationships as these are found in the vast majority of sampled trees and seem to be the norm rather than the exception.
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30

Miller, Daniel R., M. Helen Habicht, Benjamin A. Keisling, Isla S. Castañeda y Raymond S. Bradley. "A 900-year New England temperature reconstruction from in situ seasonally produced branched glycerol dialkyl glycerol tetraethers (brGDGTs)". Climate of the Past 14, n.º 11 (7 de noviembre de 2018): 1653–67. http://dx.doi.org/10.5194/cp-14-1653-2018.

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Abstract. Paleotemperature reconstructions are essential for distinguishing anthropogenic climate change from natural variability. An emerging method in paleolimnology is the use of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in sediments to reconstruct temperature, but their application is hindered by a limited understanding of their sources, seasonal production, and transport. Here, we report seasonally resolved measurements of brGDGT production in the water column, in catchment soils, and in a sediment core from Basin Pond, a small, deep inland lake in Maine, USA. We find similar brGDGT distributions in both water column and lake sediment samples but the catchment soils have distinct brGDGT distributions suggesting that (1) brGDGTs are produced within the lake and (2) this in situ production dominates the down-core sedimentary signal. Seasonally, depth-resolved measurements indicate that most brGDGT production occurs in late fall, and at intermediate depths (18–30 m) in the water column. We utilize these observations to help interpret a Basin Pond brGDGT-based temperature reconstruction spanning the past 900 years. This record exhibits trends similar to a pollen record from the same site and also to regional and global syntheses of terrestrial temperatures over the last millennium. However, the Basin Pond temperature record shows higher-frequency variability than has previously been captured by such an archive in the northeastern United States, potentially attributed to the North Atlantic Oscillation and volcanic or solar activity. This first brGDGT-based multi-centennial paleoreconstruction from this region contributes to our understanding of the production and fate of brGDGTs in lacustrine systems.
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31

Bianchi, Thomas S., Valier Galy, Brad E. Rosenheim, Michael Shields, Xingqian Cui y Peter Van Metre. "Paleoreconstruction of organic carbon inputs to an oxbow lake in the Mississippi River watershed: Effects of dam construction and land use change on regional inputs". Geophysical Research Letters 42, n.º 19 (10 de octubre de 2015): 7983–91. http://dx.doi.org/10.1002/2015gl065595.

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32

Ziveri, P., S. Thoms, I. Probert, M. Geisen y G. Langer. "A universal carbonate ion effect on stable oxygen isotope ratios in unicellular planktonic calcifying organisms". Biogeosciences Discussions 8, n.º 4 (1 de agosto de 2011): 7575–91. http://dx.doi.org/10.5194/bgd-8-7575-2011.

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Abstract. The oxygen isotopic composition (δ18O) of calcium carbonate of planktonic calcifying organisms is a key tool for reconstructing both past seawater temperature and salinity. The calibration of paloeceanographic proxies relies in general on empirical relationships derived from experiments on extant species. Laboratory experiments have more often than not revealed that variables other than the target parameter influence the proxy signal, which makes proxy calibration a challenging task. Understanding these secondary or "vital" effects is crucial for increasing proxy accuracy and possibly for developing new biomarkers. We present data from laboratory experiments showing that oxygen isotope fractionation during calcification in the coccolithophore Calcidiscus leptoporus and the calcareous dinoflagellate Thoracosphaera heimii is dependent on carbonate chemistry of seawater in addition to its dependence on temperature. A similar result has previously been reported for planktonic foraminifera, suggesting that the [CO32−] effect on δ18O is universal for unicellular calcifying planktonic organisms. The slopes of the δ18O/[CO32−] relationships range between −0.0243 (μmol kg−1)−1 (calcareous dinoflagellate T. heimii) and the previously published 0.0022 (μmol kg−1)−1 (non-symbiotic planktonic foramifera Orbulina universa), while C. leptoporus has a slope of 0.0048 (μmol kg−1)−1. We present a simple conceptual model, based on the contribution of δ18O-enriched HCO3− to the CO32− pool in the calcifying vesicle, which can explain the [CO32−] effect on δ18O for the different unicellular calcifiers. This approach provides a new insight into biological fractionation in calcifying organisms. The large range in δ18O/[CO32−] slopes should possibly be explored as a means for paleoreconstruction of surface [CO32−], particularly through comparison of the response in ecologically similar planktonic organisms.
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33

Ziveri, P., S. Thoms, I. Probert, M. Geisen y G. Langer. "A universal carbonate ion effect on stable oxygen isotope ratios in unicellular planktonic calcifying organisms". Biogeosciences 9, n.º 3 (15 de marzo de 2012): 1025–32. http://dx.doi.org/10.5194/bg-9-1025-2012.

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Abstract. The oxygen isotopic composition (δ18O) of calcium carbonate of planktonic calcifying organisms is a key tool for reconstructing both past seawater temperature and salinity. The calibration of paloeceanographic proxies relies in general on empirical relationships derived from field experiments on extant species. Laboratory experiments have more often than not revealed that variables other than the target parameter influence the proxy signal, which makes proxy calibration a challenging task. Understanding these secondary or "vital" effects is crucial for increasing proxy accuracy. We present data from laboratory experiments showing that oxygen isotope fractionation during calcification in the coccolithophore Calcidiscus leptoporus and the calcareous dinoflagellate Thoracosphaera heimii is dependent on carbonate chemistry of seawater in addition to its dependence on temperature. A similar result has previously been reported for planktonic foraminifera, supporting the idea that the [CO32−] effect on δ18O is universal for unicellular calcifying planktonic organisms. The slopes of the δ18O/[CO32−] relationships range between –0.0243‰ (μmol kg−1)−1 (calcareous dinoflagellate T. heimii) and the previously published –0.0022‰ (μmol kg−1)−1 (non-symbiotic planktonic foramifera Orbulina universa), while C. leptoporus has a slope of –0.0048 ‰ (μmol kg−1)−1. We present a simple conceptual model, based on the contribution of δ18O-enriched HCO3− to the CO32− pool in the calcifying vesicle, which can explain the [CO32−] effect on δ18O for the different unicellular calcifiers. This approach provides a new insight into biological fractionation in calcifying organisms. The large range in δ18O/[CO32−] slopes should possibly be explored as a means for paleoreconstruction of surface [CO32−], particularly through comparison of the response in ecologically similar planktonic organisms.
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34

Loewenherz, Deborah S., Christopher J. Lawrence y Richard L. Weaver. "On the Development of Transverse Ridges on Rock Glaciers". Journal of Glaciology 35, n.º 121 (1989): 383–91. http://dx.doi.org/10.1017/s002214300000931x.

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AbstractThe stability of a low Reynolds number flow on an inclined plane is investigated with respect to modelling the initiation of transverse wave-like ridges which commonly occur on the surfaces of rock-glacier forms. In accordance with field observations indicating the presence of stratification in rock glaciers, two models of rock-glacier structure are considered, each stratified and possessing a lower layer which is treated as a Newtonian fluid. An upper, less compliant layer is treated, alternatively, as a Newtonian fluid of viscosity greater than that of the lower layer, or as an elastic solid under longitudinal compression induced by a decrease in the slope of the underlying incline. A linear stability analysis is used to examine the behaviour of each of the proposed models, and both are found to generate instabilities at wavelengths comparable to those associated with transverse surficial ridges on rock glaciers. The growth rates of a flow disturbance predicted by the viscous-stratified model appear to be too slow to account fully for the development of wave forms of finite amplitude, suggesting that other mechanisms are involved in the amplification of an initial disturbance. The results of the stability analysis of the elastic lamina model indicate that finite surficial ridges may develop on rock glaciers as a product of a buckling instability in the surface region if there is a decrease in the slope of the underlying incline. Both of the analyses illustrate that transverse ridges can occur on the surface of a rock glacier in the absence of any variations in debris supply to the system. The results further imply that the use of these features in the paleoreconstruction of Holocene climatic conditions must entail an assessment of the relative roles of external climatically driven forcingversusinternal Theologically derived instability.
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35

Loewenherz, Deborah S., Christopher J. Lawrence y Richard L. Weaver. "On the Development of Transverse Ridges on Rock Glaciers". Journal of Glaciology 35, n.º 121 (1989): 383–91. http://dx.doi.org/10.3189/s002214300000931x.

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AbstractThe stability of a low Reynolds number flow on an inclined plane is investigated with respect to modelling the initiation of transverse wave-like ridges which commonly occur on the surfaces of rock-glacier forms. In accordance with field observations indicating the presence of stratification in rock glaciers, two models of rock-glacier structure are considered, each stratified and possessing a lower layer which is treated as a Newtonian fluid. An upper, less compliant layer is treated, alternatively, as a Newtonian fluid of viscosity greater than that of the lower layer, or as an elastic solid under longitudinal compression induced by a decrease in the slope of the underlying incline. A linear stability analysis is used to examine the behaviour of each of the proposed models, and both are found to generate instabilities at wavelengths comparable to those associated with transverse surficial ridges on rock glaciers. The growth rates of a flow disturbance predicted by the viscous-stratified model appear to be too slow to account fully for the development of wave forms of finite amplitude, suggesting that other mechanisms are involved in the amplification of an initial disturbance. The results of the stability analysis of the elastic lamina model indicate that finite surficial ridges may develop on rock glaciers as a product of a buckling instability in the surface region if there is a decrease in the slope of the underlying incline. Both of the analyses illustrate that transverse ridges can occur on the surface of a rock glacier in the absence of any variations in debris supply to the system. The results further imply that the use of these features in the paleoreconstruction of Holocene climatic conditions must entail an assessment of the relative roles of external climatically driven forcing versus internal Theologically derived instability.
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36

Boguslavsky, A. S., S. I. Kazakov, E. E. Lemeshko y I. G. Berzova. "HYDROGEOLOGICAL PALEORECONSTRUCTION OF FORMATION OF ANCIENT LANDSLIDES AND REMNANTS OF THE SOUTHERN COAST OF CRIMEA ON THE EXAMPLE OF SITES OF TECTONIC FRAMING OF THE LIMENIAN VOLCANIC GROUP". Ecology. Economy. Informatics. System analysis and mathematical modeling of ecological and economic systems 1, n.º 3 (2018): 135–40. http://dx.doi.org/10.23885/2500-395x-2018-1-3-135-140.

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37

Clauss, Marcus. "Bio‐ and paleoreconstructions: Correlates and proxies". Ecology and Evolution 11, n.º 16 (13 de julio de 2021): 10769–71. http://dx.doi.org/10.1002/ece3.7883.

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38

Souriau, Annie y Pascal Yiou. "Grape harvest dates for checking NAO paleoreconstructions". Geophysical Research Letters 28, n.º 20 (15 de octubre de 2001): 3895–98. http://dx.doi.org/10.1029/2001gl012870.

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39

Smerdon, Jason E., Alexey Kaplan y Diana Chang. "On the Origin of the Standardization Sensitivity in RegEM Climate Field Reconstructions*". Journal of Climate 21, n.º 24 (15 de diciembre de 2008): 6710–23. http://dx.doi.org/10.1175/2008jcli2182.1.

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Abstract The regularized expectation maximization (RegEM) method has been used in recent studies to derive climate field reconstructions of Northern Hemisphere temperatures during the last millennium. Original pseudoproxy experiments that tested RegEM [with ridge regression regularization (RegEM-Ridge)] standardized the input data in a way that improved the performance of the reconstruction method, but included data from the reconstruction interval for estimates of the mean and standard deviation of the climate field—information that is not available in real-world reconstruction problems. When standardizations are confined to the calibration interval only, pseudoproxy reconstructions performed with RegEM-Ridge suffer from warm biases and variance losses. Only cursory explanations of this so-called standardization sensitivity of RegEM-Ridge have been published, but they have suggested that the selection of the regularization (ridge) parameter by means of minimizing the generalized cross validation (GCV) function is the source of the effect. The origin of the standardization sensitivity is more thoroughly investigated herein and is shown not to be associated with the selection of the ridge parameter; sets of derived reconstructions reveal that GCV-selected ridge parameters are minimally different for reconstructions standardized either over both the reconstruction and calibration interval or over the calibration interval only. While GCV may select ridge parameters that are different from those that precisely minimize the error in pseudoproxy reconstructions, RegEM reconstructions performed with truly optimized ridge parameters are not significantly different from those that use GCV-selected ridge parameters. The true source of the standardization sensitivity is attributable to the inclusion or exclusion of additional information provided by the reconstruction interval, namely, the mean and standard deviation fields computed for the complete modeled dataset. These fields are significantly different from those for the calibration period alone because of the violation of a standard EM assumption that missing values are missing at random in typical paleoreconstruction problems; climate data are predominantly missing in the preinstrumental period when the mean climate was significantly colder than the mean of the instrumental period. The origin of the standardization sensitivity therefore is not associated specifically with RegEM-Ridge, and more recent attempts to regularize the EM algorithm using truncated total least squares could theoretically also be susceptible to the problems affecting RegEM-Ridge. Nevertheless, the principal failure of RegEM-Ridge arises because of a poor initial estimate of the mean field, and therefore leaves open the possibility that alternative methods may perform better.
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40

Stepanova, A. Yu, E. E. Taldenkova y H. A. Bauch. "Arctic quaternary ostracods and their use in paleoreconstructions". Paleontological Journal 44, n.º 1 (enero de 2010): 41–48. http://dx.doi.org/10.1134/s0031030110010065.

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41

Prushkovskaya, Irina A. y Ira B. Tsoy. "Diatoms in the Amur Bay sediments (Sea of Japan) and the impact of typhoons on their accumulation over the last 2000 years". Issues of modern algology (Вопросы современной альгологии), n.º 2(20) (2019): 252–56. http://dx.doi.org/10.33624/2311-0147-2019-2(20)-252-256.

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The study of diatoms in the sediments of the Amur Bay (Sea of Japan), formed over the last 2000 years, showed that the sharp short-term drops in the concentration of diatoms coincide with the minima of bromine content, which can be explained by the influence of typhoons or other catastrophic events leading to floods and used later in paleoreconstructions.
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42

Shabalova, M. V. y G. P. K�nnen. "Climate change scenarios: Comparisons of paleoreconstructions with recent temperature changes". Climatic Change 29, n.º 4 (abril de 1995): 409–28. http://dx.doi.org/10.1007/bf01092426.

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43

Novichkova, E. A., A. S. Savvichev, L. D. Bashirova, N. V. Kozina, A. A. Klyuvitkin, N. V. Politova, A. N. Novigatsky y A. Yu Lein. "Lithological and biogeochemical investigations of the North Atlantic sediment system (data from the 49th cruise of the R/V Akademik Ioffe)". Океанология 59, n.º 4 (17 de septiembre de 2019): 641–55. http://dx.doi.org/10.31857/s0030-1574594641-655.

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Marine sediments and samples of suspended particulate matter from the North Atlantic were studied. It is shown that modern sedimentation in this area is controlled mainly by the efficiency of autochthonous marine phytoplankton and sediment supply by the system of near-bottom currents, as well as by means of the ice-rafting. The studied sediment sections were formed in the North Atlantic during the Middle Pleistocene to Holocene. The highest sedimentation rate, up to 58.3 cm/kyr, is established for AI-3359 core, collected in the area of the Gardar and Björn Drifts. This makes the core very interesting for detailed paleoreconstructions. AI-3378 and AI-3415 cores are characterized by low sedimentation rates. Nevertheless, they are of interest for spatial paleoreconstructions on a continuous timeline. The general pattern is established for the first time for the sediments from the central North Atlantic: biogeochemically significant processes are detected only in the thin surface layer (0–2 cm) and almost completely cease at depths of 90–180 cm. The processes are probably controlled by the position of the sampling stations and the composition of organic matter (OM) but not related to the age of the sedimentary layer. The low microbial activity in the sediments is most likely the result of a lack of OM.
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44

Kolesnik, O. N., A. N. Kolesnik, E. G. Vologina y A. A. Maryash. "Mineralogical characteristic of quaternary sediments (sand fraction) from the southern extremity of the Chukchi plateau, Arctic ocean". Океанология 59, n.º 4 (17 de septiembre de 2019): 617–40. http://dx.doi.org/10.31857/s0030-1574594617-640.

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The data on mineralogical analysis of fine sand fractions in sediments accumulated in the southern part of the Chukchi Plateau during the Quaternary are presented. The associations and downcore distribution of the rock-forming and accessory minerals in relation to other characteristics are considered. The established climatically controlled mineralogical features, i. e. periodicity of warmings and coolings, can be used in solving a number of genetic problems, stratigraphic subdivision of sediments and paleoreconstructions.
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45

Razumovsky, Lev V. "Reliability estimation of reconstructions on the basis of bioindication methods unification (diatom analysis)". Issues of modern algology (Вопросы современной альгологии), n.º 2(20) (2019): 74–78. http://dx.doi.org/10.33624/2311-0147-2019-2(20)-74-78.

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The work is devoted to the unification of bioindication techniques based on diatom analysis. A new method for calculating the numerical values of pH and temperature in time was proposed. The calculation of the saprobity index (S) is used as a methodological principle of unification. Approbation of the method was carried out for lakes from different landscape and climatic zones of the European part of Russia and the results of paleoreconstructions were found to be reliable and informative.
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46

Chekhovskaya, M. P., M. A. Zenina, A. G. Matul, A. Yu Stepanova y Z. Rakowski. "Ostracod-Based Paleoreconstructions on the Northern Caspian Sea Shelf during the Holocene". Oceanology 58, n.º 1 (enero de 2018): 79–91. http://dx.doi.org/10.1134/s0001437018010010.

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47

Rodríguez, Maximiliano y Christelle Not. "Calibration of Mg ∕ Ca and Sr ∕ Ca in coastal marine ostracods as a proxy for temperature". Biogeosciences 18, n.º 6 (19 de marzo de 2021): 1987–2001. http://dx.doi.org/10.5194/bg-18-1987-2021.

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Abstract. The Mg/Ca and Sr/Ca ratios of marine shells have been widely used in environmental paleoreconstructions to understand past marine conditions. Temperature calibrations to ostracod Mg/Ca ratios are known to be species-specific but only available for a few species, despite the large number of known ostracod species. Here, we develop temperature calibrations for two shallow marine ostracods, Sinocytheridea impressa and Neomonoceratina delicata, using modern sediment samples. Our results show that adult specimens of these two species might be useful as a paleothermometer. We observed significant correlations using the Mg/Ca ratios of both species to the annual (Mg/CaS. impressa=3.7 ⋅ T−62.7; Mg/CaN. delicata=1.6 ⋅ T−16.8) and April (Mg/CaS. impressa=2.8 ⋅ T−39.2; Mg/CaN. delicata=1.6 ⋅ T−15.7) temperatures. The correlation of temperature to the Mg/Ca ratio of S. impressa is more significant and therefore should be preferred for paleoreconstructions. Re-analysis from satellite data allows us to validate our temperature calibration to an extended area around the Pearl River estuary. Our results show that Mg/Ca of S. impressa and N. delicata ostracods can be used to reconstruct water temperature at a regional scale, which provides information on the oceanic circulation in coastal areas of the South China Sea. Sr/Ca ratios of both species do not correlate with any of the 24 water parameters recorded by the Environmental Protection Department of Hong Kong, including temperature (21.7–24.1 ∘C), salinity (23.8–33.7 PSU), dissolved oxygen (4.3–7.1 mg L−1), suspended solids (1.9–35.4 mg L−1) and pH (7.7–8.2).
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48

Agrawal, P. K. y O. P. Pandey. "Effect of mobility of continents on the long wavelength potential field characteristics and paleoreconstructions". Journal of Geodynamics 33, n.º 3 (abril de 2002): 235–47. http://dx.doi.org/10.1016/s0264-3707(01)00069-2.

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49

Kovda, I., S. Sycheva, M. Lebedeva y S. Inozemtzev. "Variability of carbonate pedofeatures in a loess-paleosol sequence and their use for paleoreconstructions". Journal of Mountain Science 6, n.º 2 (10 de mayo de 2009): 155–61. http://dx.doi.org/10.1007/s11629-009-1032-4.

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50

Trebeleva, Galina, Konstantin Glazov, Andrey Kizilov, Suram Sakania, Vladlen Yurkov y Gleb Yurkov. "Roman Fortress Pitiunt: 3D-Reconstruction of the Monument Based on the Materials of Archaeological Research and Geological Paleoreconstructions". Applied Sciences 11, n.º 11 (24 de mayo de 2021): 4814. http://dx.doi.org/10.3390/app11114814.

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The present study examined the references in the works of ancient authors to the ancient city and the Roman fortress Pitiunt, the geological aspects of the formation of the coastline in the Pitsunda Cape area in the first centuries AD and the results of archaeological research of the monument performed from 1952 to 1974. The creation of the 3D reconstruction of the exterior of the Pitiunt fortress during its prosperity in the IV century AD, along with the churches which were the first monuments of religious architecture in northwestern Colchis (northwestern Colchis comprises parts of the territory of modern Russia, Georgia and Abkhazia) was carried out based on the excavation plans and the principles of fortification and temple architecture that were accepted in the late Roman times, paying special attention to the geological paleoreconstructions.
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