To see the other types of publications on this topic, follow the link: Palaeoenvironmental record; Palaeoclimate.
Journal articles on the topic 'Palaeoenvironmental record; Palaeoclimate'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Palaeoenvironmental record; Palaeoclimate.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Leng, M. J., I. Baneschi, G. Zanchetta, C. N. Jex, B. Wagner, and H. Vogel. "Late Quaternary palaeoenvironmental reconstruction from Lakes Ohrid and Prespa (Macedonia/Albania border) using stable isotopes." Biogeosciences 7, no. 10 (October 13, 2010): 3109–22. http://dx.doi.org/10.5194/bg-7-3109-2010.
Full textAbstract:
Abstract. Here we present stable isotope data from three sediment records from lakes that lie along the Macedonian-Albanian border (Lake Prespa: 1 core, and Lake Ohrid: 2 cores). The records only overlap for the last 40 kyr, although the longest record contains the MIS 5/6 transition (Lake Ohrid). The sedimentary characteristics of both lakes differ significantly between the glacial and interglacial phases. At the end of MIS 6 Lake Ohrid's water level was low (high δ18Ocalcite) and, although productivity was increasing (high calcite content), the carbon supply was mainly from inorganic catchment rock sources (high δ13Ccarb). During the last interglacial, calcite and TOC production and preservation increased, progressively lower δ18Ocalcite suggest increase in humidity and lake levels until around 115 ka. During ca. 80 ka to 11 ka the lake records suggest cold conditions as indicated by negligible calcite precipitation and low organic matter content. In Lake Ohrid, δ13Corg are complacent; in contrast, Lake Prespa shows consistently higher δ13Corg suggesting a low oxidation of 13C-depleted organic matter in agreement with a general deterioration of climate conditions during the glacial. From 15 ka to the onset of the Holocene, calcite and TOC begin to increase, suggesting lake levels were probably low (high δ18Ocalcite). In the Holocene (11 ka to present) enhanced productivity is manifested by high calcite and organic matter content. All three cores show an early Holocene characterised by low δ18Ocalcite, apart from the very early Holocene phase in Prespa where the lowest δ18Ocalcite occurs at ca. 7.5 ka, suggesting a phase of higher lake level only in (the more sensitive) Lake Prespa. From 6 ka, δ18Ocalcite suggest progressive aridification, in agreement with many other records in the Mediterranean, although the uppermost sediments in one core records low δ18Ocalcite which we interpret as a result of human activity. Overall, the isotope data present here confirm that these two big lakes have captured the large scale, low frequency palaeoclimate variation that is seen in Mediterranean lakes, although in detail there is much palaeoclimate information that could be gained, especially small scale, high frequency differences between this region and the Mediterranean.
2
Leng, M. J., I. Baneschi, G. Zanchetta, C. N. Jex, B. Wagner, and H. Vogel. "Late Quaternary palaeoenvironmental reconstruction from Lakes Ohrid and Prespa (Macedonia/Albania border) using stable isotopes." Biogeosciences Discussions 7, no. 3 (May 21, 2010): 3815–53. http://dx.doi.org/10.5194/bgd-7-3815-2010.
Full textAbstract:
Abstract. Here we present stable isotope data from three sediment records from lakes that lie along the Macedonian-Albanian border (Lake Prespa: 1 core, and Lake Ohrid: 2 cores). The records only overlap for the last 40 kyr, although the longest record contains the MIS 5/6 transition (Lake Ohrid). The sedimentary characteristics of both lakes differ significantly between the glacial and interglacial phases. At the end of MIS 6 Lake Ohrid's water level was low (high δ18Ocalcite) and, although productivity was increasing (high calcite content), the carbon supply was mainly from inorganic catchment rock sources (high δ13Ccarb). During the last interglacial, calcite and TOC production and preservation increased, progressively lower δ18Ocalcite suggest increase in humidity and lake levels till around 115 ka. During ca. 80 ka to 11 ka the lake records suggest cold conditions as indicated by negligible calcite precipitation and low organic matter content. In Lake Ohrid δ13Corg are complacent, in contrast Lake Prespa shows consistently higher δ13Corg suggesting a low oxidation of 13C-depleted organic matter in agreement with a general deterioration of climate conditions during the glacial. From 15 ka to the onset of the Holocene, calcite and TOC begin to increase, suggesting lake levels were probably low (high δ18Ocalcite). In the Holocene (11 ka to present) enhanced productivity is manifested by high calcite and organic matter content. All three cores show an early Holocene characterised by low δ18Ocalcite, apart from the very early Holocene phase in Prespa where the lowest δ18Ocalcite occurs at ca. 7.5 ka, suggesting a phase of higher lake level only in (the more sensitive) Lake Prespa. From 6 ka δ18Ocalcite suggest progressive aridification, in agreement with many other records in the Mediterranean, although the uppermost sediments in one core records low δ18Ocalcite which we interpret as a result of human activity. Overall, the isotope data present here confirm that these two big lakes have captured the large scale, low frequency palaeoclimate variation that is seen in Mediterranean lakes, although in detail there is much palaeoclimate information that could be gained, especially small scale, high frequency differences between this region and the Mediterranean.
3
Makaroğlu, Özlem, Norbert R. Nowaczyk, Kadir K. Eriş, and M. Namık Çağatay. "High-resolution palaeomagnetic record from Sea of Marmara sediments for the last 70 ka." Geophysical Journal International 222, no. 3 (June 5, 2020): 2024–39. http://dx.doi.org/10.1093/gji/ggaa281.
Full textAbstract:
SUMMARY Magnetostratigraphic and geochemical analyses were performed on two sediment cores recovered from the Sea of Marmara to investigate geomagnetic field variations over the last 70 ka. A chronology for each of the two cores was developed from eight AMS 14C datings, tephrochronology, and tuning of Ca concentrations with stadials and interstadials observed in Greenland ice core oxygen isotope data. Based on the age models, cores MD01–2430 and MRS-CS19 reach back to 70 and 32 ka, respectively. High average sedimentation rates of 43 cm kyr–1 for core MD01–2430 and 68 cm kyr–1 for core MRS-CS19 allow high-resolution reconstruction of geomagnetic field variations for the Sea of Marmara. Mineral magnetic properties are sensitive to glacioeustatic sea level changes and palaeoclimate variations in this region, reflecting the variable palaeoenvironmental conditions of the Sea of Marmara during last 70 ka. Despite the impairment of the palaeomagnetic record in some stratigraphic intervals due to early diagenesis, relative palaeointensity variations in the Sea of Marmara sediments correlate well with similar records derived from other regions, such as the nearby Black Sea and the GLOPIS-75 stack. The directional record derived from the Sea of Marmara cores exhibits typical palaeosecular variation patterns, with directional anomalies at 41 and 18 ka, representing the Laschamps and postulated Hilina Pali excursions, respectively. Both directional anomalies are also associated with palaeointensity minima. A further palaeointensity minimum at 34.5 ka is likely related to the Mono Lake excursion, with no directional deviation documented in the Sea of Marmara palaeomagnetic record so far.
4
Opel, Thomas, Sebastian Wetterich, Hanno Meyer, Alexander Y. Dereviagin, Margret C. Fuchs, and Lutz Schirrmeister. "Ground-ice stable isotopes and cryostratigraphy reflect late Quaternary palaeoclimate in the Northeast Siberian Arctic (Oyogos Yar coast, Dmitry Laptev Strait)." Climate of the Past 13, no. 6 (June 6, 2017): 587–611. http://dx.doi.org/10.5194/cp-13-587-2017.
Full textAbstract:
Abstract. To reconstruct palaeoclimate and palaeoenvironmental conditions in the northeast Siberian Arctic, we studied late Quaternary permafrost at the Oyogos Yar coast (Dmitry Laptev Strait). New infrared-stimulated luminescence ages for distinctive floodplain deposits of the Kuchchugui Suite (112.5 ± 9.6 kyr) and thermokarst-lake deposits of the Krest Yuryakh Suite (102.4 ± 9.7 kyr), respectively, provide new substantial geochronological data and shed light on the landscape history of the Dmitry Laptev Strait region during Marine Isotope Stage (MIS) 5. Ground-ice stable-isotope data are presented together with cryolithological information for eight cryostratigraphic units and are complemented by data from nearby Bol'shoy Lyakhovsky Island. Our combined record of ice-wedge stable isotopes as a proxy for past winter climate conditions covers about 200 000 years and is supplemented by stable isotopes of pore and segregated ice which reflect annual climate conditions overprinted by freezing processes. Our ice-wedge stable-isotope data indicate substantial variations in northeast Siberian Arctic winter climate conditions during the late Quaternary, in particular between glacial and interglacial times but also over the last millennia to centuries. Stable isotope values of ice complex ice wedges indicate cold to very cold winter temperatures about 200 kyr ago (MIS7), very cold winter conditions about 100 kyr ago (MIS5), very cold to moderate winter conditions between about 60 and 30 kyr ago, and extremely cold winter temperatures during the Last Glacial Maximum (MIS2). Much warmer winter conditions are reflected by extensive thermokarst development during MIS5c and by Holocene ice-wedge stable isotopes. Modern ice-wedge stable isotopes are most enriched and testify to the recent winter warming in the Arctic. Hence, ice-wedge-based reconstructions of changes in winter climate conditions add substantial information to those derived from paleoecological proxies stored in permafrost and allow a distinction between seasonal trends of past climate dynamics. Future progress in ice-wedge dating and an improved temporal resolution of ice-wedge-derived climate information may help to fully explore the palaeoclimatic potential of ice wedges.
5
Schittek, K., S. T. Kock, A. Lücke, C. Ohlendorf, J. J. Kulemeyer, L. C. Lupo, and F. Schäbitz. "Environmental and climatic history in the NW Argentine Andes (24° S) over the last 2100 years inferred from a high-altitude peatland record." Climate of the Past Discussions 11, no. 3 (May 27, 2015): 2037–76. http://dx.doi.org/10.5194/cpd-11-2037-2015.
Full textAbstract:
Abstract. High-altitude cushion peatlands are versatile archives for high-resolution palaeoenvironmental studies, due to their high accumulation rates, range of proxies and sensitivity to climatic and/or human-induced changes. Especially within the central Andes, the knowledge about climate conditions during the Holocene is limited. In this study, we present the environmental and climatic history for the last 2100 years of Cerro Tuzgle peatland (CTP), which is located in the dry Puna of NW Argentina, based on a multi-proxy approach. X-ray fluorescence (XRF), stable isotope and element content analyses (δ13C, δ15N, TN and TOC) were conducted to analyse the inorganic geochemistry throughout the sequence, revealing changes in the peatland's past redox conditions. Pollen assemblages give an insight into substantial environmental changes on a regional scale. The palaeoclimate varied significantly during the last 2100 years. The results reflect prominent late Holocene climate anomalies and provide evidence that Northern Hemisphere temperature oscillations were extensive and affected the southward migration of the Intertropical Convergence Zone (ITCZ), and hence, the intensity of moisture flux within the South American Summer Monsoon (SASM) belt. Volcanic forcing at the beginning of the 19th century (1815 Tambora eruption) seems to have had an impact on climatic settings in the central Andes. In the past, the peatland recovered from climatic perturbations. Nowadays, CTP is heavily degraded by human interventions, and the peat deposit becomes increasingly susceptible to erosion and incision.
6
Drake, Nicholas, Mustapha Salem, Simon Armitage, Jan Francke, Mark Hounslow, Osama Hlal, Kevin White, and Ahmed El-Hawat. "DMP XV: Palaeohydrology and Palaeoenvironment: Initial Results and Report of 2010 and 2011 Fieldwork." Libyan Studies 42 (2011): 139–49. http://dx.doi.org/10.1017/s0263718900004878.
Full textAbstract:
AbstractThis paper reports the results of fieldwork conducted in the 2010 and 2011 DMP field seasons and of analysis of samples collected during these and previous years. Research has involved 1) studying palaeolake sediment outcrops, 2) using ground penetrating radar (GPR) to determine their extent under the Dahān Ubārī, and 3) coring palaeolakes in order to determine their palaeoenvironmental records. Research on these samples is continuing but some initial findings are discussed in this paper. The most extensive palaeolake sediments are found within the al-Mahruqah Formation and were deposited by a giant lake system that developed in the Fazzān Basin during past humid periods. Stratigraphic analysis of Lake Megafazzān sediments suggests two different sedimentary successions, a lake margin succession distinctive for its lacustrine and palaeosol carbonates, and a clastic-dominated, intensely rootleted, basin-centre succession which has terrestrial intervals (aeolian and palaeosols) as well as in the upper parts lacustrine limestones. Both basin margin and basin centre successions are underlain by fluvial deposits. Magnetostratigraphy suggests that the formation may be as old as the mid-Pliocene. After the Lake Megafazzān phase, smaller palaeolakes developed within the basin during subsequent humid periods. One of the largest is found in the Wādī al-Hayāt in the area between Jarma and Ubārī. Similar deposits further west along the Wādī at progressively higher altitudes are interpreted as small lakes and marshes fed by springs issuing from aquifers at the base of the escarpment, last replenished during the Holocene humid phase. Dating of sediments suggests that this was between c. 11 and c. 8 ka. The Wādī ash-Shāţī palaeolake core also provides a Holocene palaeoclimate record that paints a slightly different picture, indicating lake conditions until around 7 ka, whereupon it started oscillating until around 5.5 ka when sedimentation terminates. The reasons for the differences in these records are discussed.
7
Schittek, Karsten, Sebastian T. Kock, Andreas Lücke, Jonathan Hense, Christian Ohlendorf, Julio J. Kulemeyer, Liliana C. Lupo, and Frank Schäbitz. "A high-altitude peatland record of environmental changes in the NW Argentine Andes (24 ° S) over the last 2100 years." Climate of the Past 12, no. 5 (May 13, 2016): 1165–80. http://dx.doi.org/10.5194/cp-12-1165-2016.
Full textAbstract:
Abstract. High-altitude cushion peatlands are versatile archives for high-resolution palaeoenvironmental studies, due to their high accumulation rates, range of proxies, and sensitivity to climatic and/or human-induced changes. Especially within the Central Andes, the knowledge about climate conditions during the Holocene is limited. In this study, we present the environmental and climatic history for the last 2100 years of Cerro Tuzgle peatland (CTP), located in the dry Puna of NW Argentina, based on a multi-proxy approach. X-ray fluorescence (XRF), stable isotope and element content analyses (δ13C, δ15N, TN and TOC) were conducted to analyse the inorganic geochemistry throughout the sequence, revealing changes in the peatlands' past redox conditions. Pollen assemblages give an insight into substantial environmental changes on a regional scale. The palaeoclimate varied significantly during the last 2100 years. The results reflect prominent late Holocene climate anomalies and provide evidence that in situ moisture changes were coupled to the migration of the Intertropical Convergence Zone (ITCZ). A period of sustained dry conditions prevailed from around 150 BC to around AD 150. A more humid phase dominated between AD 200 and AD 550. Afterwards, the climate was characterised by changes between drier and wetter conditions, with droughts at around AD 650–800 and AD 1000–1100. Volcanic forcing at the beginning of the 19th century (1815 Tambora eruption) seems to have had an impact on climatic settings in the Central Andes. In the past, the peatland recovered from climatic perturbations. Today, CTP is heavily degraded by human interventions, and the peat deposit is becoming increasingly susceptible to erosion and incision.
8
Vossel, Hannah, Patricia Roeser, Thomas Litt, and Jane M. Reed. "Lake Kinneret (Israel): New insights into Holocene regional palaeoclimate variability based on high-resolution multi-proxy analysis." Holocene 28, no. 9 (June 11, 2018): 1395–410. http://dx.doi.org/10.1177/0959683618777071.
Full textAbstract:
The southern Levant is a Mediterranean climate zone of complex variability in which uncertainty remains in regional palaeoclimate reconstruction. In spite of the proven value of diatoms in circum-Mediterranean palaeoenvironmental research, their potential remains largely unexplored in the southern Levant region. In this study, we generate a new, high-resolution multi-proxy record for the last ca. 9000 cal. yr BP, supported by diatom data and key biological, mineralogical and geochemical indicators preserved in a 17.8-m-long sediment sequence recovered from Lake Kinneret (the Sea of Galilee), Israel. During the Holocene, well-correlated shifts in the diatom, minero-geochemical and palynological data indicate marked lake-level variation over time as well as changes in the trophic state of Lake Kinneret. Our results are particularly important in improving the reconstruction of Holocene lake-level variation, and thus past moisture availability. Diatom-inferred lake-level oscillations correlate well with the output from climatic models from the Levantine region and clarify previous uncertainty concerning regional variation in moisture availability. The Early Holocene (from ca. 9000 to 7400 cal. yr BP) was characterized by lake-level shifts due to fluctuating dry-wet climate conditions. During the mid-Holocene (from 7400 to 2200 cal. yr BP), a stable, deep lake-level phase persisted due to high humidity. The lake level of modern Lake Kinneret not only fluctuates seasonally with available moisture, but has also been influenced for ca. 2000 years by the impacts of water abstraction for human consumption and agriculture. Over the last 9000 cal. yr BP, the trophic state of Lake Kinneret has changed from an oligotrophic to a meso- to eutrophic environment, mainly triggered by increased human impact from around 2200 cal. yr BP onwards. The lake’s ecosystem status was not strongly affected by the documented major changes in human occupation patterns during the mid-Holocene, when a relatively stable environment persisted.
9
Stone, Abi E. C. "Last Glacial Maximum conditions in southern Africa." Progress in Physical Geography: Earth and Environment 38, no. 5 (April 8, 2014): 519–42. http://dx.doi.org/10.1177/0309133314528943.
Full textAbstract:
The Last Glacial Maximum (LGM) (21±2 ka) is an important period for which to understand past climatic and environmental conditions. In particular it is a key time-slice for evaluating the performance of numerical climate model simulations of glacial palaeoclimates using palaeoenvironmental data sets. However, our palaeoenvironmental data sets and reconstructions of climatic conditions at the LGM are still debated in certain regions. This is the case for southern Africa, despite more than half a century of research since early conceptual models of palaeoclimate were proposed. The greatest debates are about the spatial patterning of relatively wetter and drier conditions than present and the position of the mid-latitude westerlies at the LGM. Different patterns emerge from: separate syntheses of palaeoenvironmental proxies, from different numerical model simulations and from comparisons of the two. In this review of the progress over half a century of research in southern Africa: (1) a brief historical review of key conceptual models is given, (2) key points of conflict that emerge in synthesis of palaeoenvironmental proxy records are outlined and (3) numerical model simulations are considered. From these, some points for future progress are suggested.
10
PRADO-PÉREZ, ANTONIO J., ANTONIO DELGADO HUERTAS, M. T. CRESPO, A. MARTÍN SÁNCHEZ, and LUÍS PÉREZ DEL VILLAR. "Late Pleistocene and Holocene mid-latitude palaeoclimatic and palaeoenvironmental reconstruction: an approach based on the isotopic record from a travertine formation in the Guadix-Baza basin, Spain." Geological Magazine 150, no. 4 (January 23, 2013): 602–25. http://dx.doi.org/10.1017/s0016756812000726.
Full textAbstract:
AbstractA comprehensive palaeoenvironmental reconstruction of the last 219 ka has been carried out by determining the isotopic signatures (δ18O and δ13C) in 766 samples of a thermogene travertine formation in the Guadix-Baza Tertiary basin (Granada, SE Spain). This travertine formation was dated from ≈ 220 to ≈ 5 ka by means of the alpha-spectrometry technique. Initially, the study of the δ18O values of the travertine formation was carried out because they are excellent indicators of the overall palaeoclimatic condition of a particular site. Likewise, the evolution of δ13C values, which can be directly related to the biomass development of the site, has also been studied. Finally, an integrated study of both isotopic records has been performed, identifying a total of 12 climatic periods based on their palaeoclimatic and palaeoenvironmental conditions. These periods are grouped into four climatic scenarios: scenario A, characterized by warm and dry periods; scenario B, characterized by cold and humid periods; scenario C, constituted by warm and humid periods; and scenario D, which is characterized by cold and dry periods. Palaeoclimatic scenarios A and B mainly characterized the palaeoclimatic evolution of the site, while in northern Europe the palaeoclimatic evolution is mainly characterized by scenarios C and D. Therefore, it is suggested that the palaeoenvironmental evolution at lower latitudes on the Iberian Peninsula is the opposite of that identified in northern Europe. However, the main climatic events identified at higher latitudes are also reflected in the studied area.
11
Vött, Andreas, Timo Willershäuser, Björn R. Röbke, Lea Obrocki, Peter Fischer, Hanna Hadler, Kurt Emde, Birgitta Eder, Hans-Joachim Gehrke, and Franziska Lang. "Major flood events recorded in the Holocene sedimentary sequence of the uplifted Ladiko and Makrisia basins near ancient Olympia (western Peloponnese, Greece)." Zeitschrift für Geomorphologie, Supplementary Issues 62, no. 2 (October 1, 2019): 143–95. http://dx.doi.org/10.1127/zfg_suppl/2018/0499.
Full textAbstract:
Detailed palaeoenvironmental studies were conducted in the Ladiko and Makrisia basins near the Alpheios River and ancient Olympia (western Peloponnese, Greece) to assess major landscape changes during the Holocene. Previous studies and literature data document that the area experienced crust uplift of minimum 13 m to 30 m since the mid-Holocene. Geological archives were sampled along a vibracore transect connecting the Ladiko and Makrisia basins. Sediment cores were analyzed using sedimento-logical, geochemical and micropalaeontological methods. Geochronological reconstruction of major landscape changes is based on a set of 24 radiocarbon dates. Geophysical studies were carried out using electrical resistivity tomography (ERT) and Direct Push-Electrical Conductivity (DP-EC) measurements to detect stratigraphic changes and subsurface bedrock structures. The stratigraphic record of the uplifted lake basins of Ladiko and Makrisia revealed two major lithostratigraphic units. Unit I, predominantly composed of clay, silt and silty fine sand, reflects prevailing low-energy sedimentary conditions typical of quiescent (fluvio-)limnic waterbodies. Unit II is made out of fine to coarse sand and documents repeated interferences of unit I associated with abrupt and temporary high-energy flood type (= heft) events. We found signals of four different heft events (H1 to H4) showing strong stratigraphic and geochronological consistencies along the vibracore transect. The following age ranges were determined: H1 – between 4360 – 4330 cal BC and 4320 – 4080 cal BC; H2 – be- tween 2830 – 2500 cal BC and 2270 – 2140 cal BC; H3 – between 1220 –1280 cal AD and 1290 –1390 cal AD; H4 – between 1640 –1800 cal AD and 1650 –1800 cal AD. Different hypotheses concerning the characteristics, potential trigger mechanisms and causes of the flood events were tested against the background of strong Holocene crust uplift and using a variety of different methodological approaches: Geomorphological and granulometric aspects, micropalaeontological contexts, geochronological data sets, numerical simulation of flooding events, local tectonic uplift, and the palaeoclimate background were taken into account. We hypothesize that, during the mid-Holocene, the study area was affected by tsunami events, namely between 4360 – 4330 cal BC and 4320 – 4080 cal BC (H1) and between 2830 – 2500 cal BC and 2270 – 2140 cal BC (H2). These ages are very well consistent with the supra-regional and regional tsunami event signal retrieved from many coastal archives in large parts of western Greece. The timing of flood events H1 and H2 is highly consistent with ages of (supra-)regional tectonic events known from literature and is not consistent with increased flood indices of palaeoclimate data available for western Greece. Tsunami inundation scenarios based on numerical simulation are highly consistent with vibracoring and geophysical (ERT, DP-EC) data. In contrast, heft events H3 and H4 are possibly related to phases of increased precipi- tation and flooding activity in the Mediterranean or to land-based geomorphological processes triggered by regional tectonic events (RTE). Neolithic, Chalcolithic as well as Early and Middle Helladic human activities documented at ancient Olympia were most probably affected by tsunami heft events H1 and H2. Sandy deposits of tsunami event H2, covering the prehistorical tumulus, seem to have been used as a higher and dry base to construct the apsidal houses in the center of the later sanctuary at Olympia. The site, already abandoned, must have again been subject to major flood events during the 13/14th cent. AD and the 17–19th cent. AD associated with heft events H3 and H4.
12
Goodwin, Ian D., and Carol J. Pudsey. "Introduction." Antarctic Science 10, no. 3 (September 1998): 225–26. http://dx.doi.org/10.1017/s0954102098000315.
Full textAbstract:
This issue contains a group of papers selected from those presented at the 1st workshop of the SCAR-GLOCHANT and IGBP-PAGES cosponsored programme on the Late Quaternary Sedimentary Record of the Antarctic Ice Margin Evolution (ANTIME), held in Hobart, 6-1 1 July 1997. ANTIME is focused on the circurn Antarctic reconstruction of palaeoclimate, palaeoenvironment, and ice sheet palaeogeography throughout the last glacial cycle. There were 65 participants from Australia, USA, UK, Italy, Spain, Japan, Sweden, Germany and Russia at the workshop. The participants included representatives of PAGES, IMAGES, and INQUA. The workshop included three scientific sessions on: Extent, timing and regional differences during Glacial Stage 2 (10–30 kyr BP) in Antarctica, from the terrestrial and marine records;Climatic, environmental and glacial events during the Holocene;Late Quaternary geochronological problems in Antarctica.
13
Stefanini, Bettina S., Pirita O. Oksanen, John P. Corcoran, and Fraser JG Mitchell. "Appraising the cohesion of palaeoenvironmental reconstructions in north-west Spain since the mid-Holocene from a high temporal resolution multi-proxy peat record." Holocene 28, no. 5 (December 7, 2017): 681–94. http://dx.doi.org/10.1177/0959683617744258.
Full textAbstract:
Investigation of abrupt palaeohydrological regime change remains challenging due to site-specific noise ratios and the limitations of dating control and spatial resolution of multi-proxy records. Some of these issues are addressed through a well dated and highly resolved record from an ombrotrophic peatland in Galicia, north-west Spain. The site is in an ideal location to record marine influences and test models of past palaeoclimatic boundaries and ocean-atmosphere linkages through multi-proxy records of macrofossils, microfossils, charcoal, peat humification and loss-on-ignition data. In conjunction with many regional proxy records of terrestrial and marine origin, the data suggest spatial coherence between 5300 and ca. 3300 cal. BP and continue to link to marine responses afterwards. After ca. 2000 cal. BP, episodes of spatially consistent palaeohydrological change persist but become more short-lived, local and sporadic in north-west Iberia. These indicate an increase in the complexity of drivers of palaeoenvironmental change in recent millennia. Fire history inferred from microscopic charcoal and apparent upland erosion indicated by the loss-on-ignition profile relate to anthropogenic pressure and appear to be linked to local deforestation phases in the Xistral uplands.
14
Martin, Louis, Marc Fournier, Philippe Mourguiart, Abdelfatah Sifeddine, Bruno Turcq, Jean-Marie Flexor, and Maria Lucia Absy. "Southern Oscillation Signal in South American Palaeoclimatic Data of the Last 7000 Years." Quaternary Research 39, no. 3 (May 1993): 338–46. http://dx.doi.org/10.1006/qres.1993.1040.
Full textAbstract:
AbstractDuring strong El Niño events, rainfall anomalies and changes in wind patterns are observed in different regions of South America. Along the central Brazilian coast, during the 1983 El Niño year, the frontal systems were blocked to the south, provoking a reversal of the longshore sand transport. Long-duration reversals of longshore transport were also recorded in Holocene beach-ridge terraces from the Rio Doce coastal plain. This led to the formulation of a model relating these reversals of longshore transport to El Niño-like conditions. El Niño-like conditions are past average climate situations that generate the same perturbations as the strong El Niño events observed during the last decade. They are likely to correspond to the long-duration low phase of the Southern Oscillation. To confirm this hypothesis we compared the Holocene beach-ridge record with other palaeoenvironmental records from regions where strong El Niño events would have a substancial signal as well: (1) water-level fluctuations of Lake Titicaca, (2) a pollen and sediment record in an eastern Amazonian lake, (3) changes of the Rio Xingu discharge in eastern Amazonia, and (4) variations of sand supply at the Rio Piura and Rio Chira outlets in the Sechura Desert. The occurrences of El Niño-like conditions were numerous before 3900-3600 yr B.P., absent between 39003600 and 2800-2500 yr B.P., and infrequent after 2800-2500 yr B.P.
15
Kageyama, Masa, Pascale Braconnot, Sandy P. Harrison, Alan M. Haywood, Johann H. Jungclaus, Bette L. Otto-Bliesner, Jean-Yves Peterschmitt, et al. "The PMIP4 contribution to CMIP6 – Part 1: Overview and over-arching analysis plan." Geoscientific Model Development 11, no. 3 (March 16, 2018): 1033–57. http://dx.doi.org/10.5194/gmd-11-1033-2018.
Full textAbstract:
Abstract. This paper is the first of a series of four GMD papers on the PMIP4-CMIP6 experiments. Part 2 (Otto-Bliesner et al., 2017) gives details about the two PMIP4-CMIP6 interglacial experiments, Part 3 (Jungclaus et al., 2017) about the last millennium experiment, and Part 4 (Kageyama et al., 2017) about the Last Glacial Maximum experiment. The mid-Pliocene Warm Period experiment is part of the Pliocene Model Intercomparison Project (PlioMIP) – Phase 2, detailed in Haywood et al. (2016).The goal of the Paleoclimate Modelling Intercomparison Project (PMIP) is to understand the response of the climate system to different climate forcings for documented climatic states very different from the present and historical climates. Through comparison with observations of the environmental impact of these climate changes, or with climate reconstructions based on physical, chemical, or biological records, PMIP also addresses the issue of how well state-of-the-art numerical models simulate climate change. Climate models are usually developed using the present and historical climates as references, but climate projections show that future climates will lie well outside these conditions. Palaeoclimates very different from these reference states therefore provide stringent tests for state-of-the-art models and a way to assess whether their sensitivity to forcings is compatible with palaeoclimatic evidence. Simulations of five different periods have been designed to address the objectives of the sixth phase of the Coupled Model Intercomparison Project (CMIP6): the millennium prior to the industrial epoch (CMIP6 name: past1000); the mid-Holocene, 6000 years ago (midHolocene); the Last Glacial Maximum, 21 000 years ago (lgm); the Last Interglacial, 127 000 years ago (lig127k); and the mid-Pliocene Warm Period, 3.2 million years ago (midPliocene-eoi400). These climatic periods are well documented by palaeoclimatic and palaeoenvironmental records, with climate and environmental changes relevant for the study and projection of future climate changes. This paper describes the motivation for the choice of these periods and the design of the numerical experiments and database requests, with a focus on their novel features compared to the experiments performed in previous phases of PMIP and CMIP. It also outlines the analysis plan that takes advantage of the comparisons of the results across periods and across CMIP6 in collaboration with other MIPs.
16
Harrison, Sandy P., Marie-José Gaillard, Benjamin D. Stocker, Marc Vander Linden, Kees Klein Goldewijk, Oliver Boles, Pascale Braconnot, et al. "Development and testing scenarios for implementing land use and land cover changes during the Holocene in Earth system model experiments." Geoscientific Model Development 13, no. 2 (March 2, 2020): 805–24. http://dx.doi.org/10.5194/gmd-13-805-2020.
Full textAbstract:
Abstract. Anthropogenic changes in land use and land cover (LULC) during the pre-industrial Holocene could have affected regional and global climate. Existing scenarios of LULC changes during the Holocene are based on relatively simple assumptions and highly uncertain estimates of population changes through time. Archaeological and palaeoenvironmental reconstructions have the potential to refine these assumptions and estimates. The Past Global Changes (PAGES) LandCover6k initiative is working towards improved reconstructions of LULC globally. In this paper, we document the types of archaeological data that are being collated and how they will be used to improve LULC reconstructions. Given the large methodological uncertainties involved, both in reconstructing LULC from the archaeological data and in implementing these reconstructions into global scenarios of LULC, we propose a protocol to evaluate the revised scenarios using independent pollen-based reconstructions of land cover and climate. Further evaluation of the revised scenarios involves carbon cycle model simulations to determine whether the LULC reconstructions are consistent with constraints provided by ice core records of CO2 evolution and modern-day LULC. Finally, the protocol outlines how the improved LULC reconstructions will be used in palaeoclimate simulations in the Palaeoclimate Modelling Intercomparison Project to quantify the magnitude of anthropogenic impacts on climate through time and ultimately to improve the realism of Holocene climate simulations.
17
Narcisi, Biancamaria. "Palaeoenvironmental and palaeoclimatic implications of the Late-Quaternary sediment record of Vico volcanic lake (central Italy)." Journal of Quaternary Science 16, no. 3 (2001): 245–55. http://dx.doi.org/10.1002/jqs.594.
Full text
18
Salvi, Cristinamaria, Gianguido Salvi, Barbara Stenni, and Antonio Brambati. "Palaeoproductivity in the Ross Sea, Antarctica, during the last 15 kyr BP and its link with ice-core temperature proxies." Annals of Glaciology 39 (2004): 445–51. http://dx.doi.org/10.3189/172756404781814582.
Full textAbstract:
AbstractA detailed study of organic carbon content obtained from two sediment cores collected in the Joides basin, western Ross Sea, Antarctica, was carried out. The variations observed during the last deglaciation and the Holocene were compared to the high-resolution climatic records (EPICA DC and Taylor Dome) preserved in the ice. The importance of the carbon content as a proxy for palaeoclimatic and palaeoenvironmental changes was investigated. A dramatic decrease in the Ross Sea palaeoproductivity was observed during the Antarctic Cold Reversal (12.5–14 kyr BP). Another decrease in total organic carbon in the second half of the Holocene (after 5–6 kyr BP) confirms the climate worsening observed in previous studies.
19
Marquer, L., S. Pomel, A. Abichou, E. Schulz, D. Kaniewski, and E. Van Campo. "Late Holocene high resolution palaeoclimatic reconstruction inferred from Sebkha Mhabeul, southeast Tunisia." Quaternary Research 70, no. 2 (September 2008): 240–50. http://dx.doi.org/10.1016/j.yqres.2008.06.002.
Full textAbstract:
AbstractRelations between climate change and landscape evolution during the last two millennia in southeastern coastal Tunisia have been documented using high-resolution reconstruction of flood history and fire activity in the Sebkha Mhabeul core. The age model, based on tephrochronology, indicates that the core extends from Roman to modern times and encompasses the well-defined climatic periods of the last two millennia. This record provides a first palaeoecological/palaeoclimatic high resolution reconstruction in North Africa using a cross-disciplinary approach with both physical (grey-scale intensity, quartz particles) and biological (charcoal and pollen) indicators. The flood history shows four wet/dry cycles (ca. AD 550–950, 950–1300, 1300–1570 and 1570–1870) of different duration. Major hydrological instabilities are concentrated during the Medieval Climate Anomalies and the early Little Ice Age, between AD 1000 and 1550. Direct correlation between climate and fire cannot be established suggesting that the fire history of the Sebkha environment is mainly influenced by human activity. This study demonstrates the great value of sebkhas as palaeoenvironmental archives.
20
Pratte, Steve, Kunshan Bao, Atindra Sapkota, Wenfang Zhang, Ji Shen, Gaël Le Roux, and François De Vleeschouwer. "14 kyr of atmospheric mineral dust deposition in north-eastern China: A record of palaeoclimatic and palaeoenvironmental changes in the Chinese dust source regions." Holocene 30, no. 4 (December 18, 2019): 492–506. http://dx.doi.org/10.1177/0959683619892661.
Full textAbstract:
A multi-proxy record of Holocene and late-Pleistocene aeolian mineral dust is reconstructed using a combination of geochemical (trace elements), mineralogical and grain-size analyses on cores from the Hani peatland in north-eastern (NE) China. The dust record displays a sharp increase in dust deposition during the late Holocene in comparison to the rest of the Holocene. This trend is in line with climatic records from the Chinese dust source regions and their downwind areas, which generally show an increase in aridity and aeolian activity during the late Holocene. The larger part of the Chinese dust source regions experienced a gradual increase in effective moisture and vegetation cover reaching maxima during the middle Holocene (6.0–8.0 kyr cal. BP) co-occurring with the minima in dust deposition in Hani. These changes in the dust source regions are likely to have been modulated by the variations in the East Asian summer monsoon (EASM), which is the principal mechanism controlling climate in the region. The intensified EASM during the middle Holocene is also likely to have resulted in a sediment recharge at the margin of the Chinese drylands providing additional material and enhancing the atmospheric dust load after the late-Holocene aridification of the region. Combined together, these changes promoted a remobilization of dust sources increasing the amount of material available for transport by the East Asian winter monsoon (EAWM) and the Westerlies. Human activities might also have played a role in the increased dust emissions during the late Holocene, but further research is needed to assess the extent of those impacts at a regional level.
21
Zhang, Qiang, Qingsong Liu, and Youbin Sun. "Review of recent developments in aeolian dust signals of sediments from the North Pacific Ocean based on magnetic minerals." Geological Magazine 157, no. 5 (July 18, 2019): 790–805. http://dx.doi.org/10.1017/s0016756819000712.
Full textAbstract:
AbstractThe North Pacific Ocean (NPO) has received abundant aeolian dust transported by westerlies from the Asian inland. The aeolian components preserved in NPO sediments record information on palaeoclimatic and palaeoenvironmental changes in Asian source areas at different timescales. Previous studies have systematically investigated the source–sink effect of aeolian dust using the sedimentology, geochemistry, isotope and magnetic methods. In this study, we focus more on recent developments of aeolian signals in NPO sediments obtained by magnetic approaches. Generally, aeolian components contain a mixture of magnetite, maghemite, hematite and goethite of different origins. Magnetic properties (mineral category, concentration and particle size) of these minerals are modulated primarily by climatic/environmental conditions in source areas and sorting effects during the transportation process. Compared with the other methods, magnetic measurements have the advantages of non-sample destruction, high sensitivity and high efficiency. Finally, future studies are also discussed to address the importance of magnetism for tracing the dynamic transportation processes of the aeolian dust.
22
Conran, John G., Raymond J. Carpenter, and Gregory J. Jordan. "Early Eocene Ripogonum (Liliales: Ripogonaceae) leaf macrofossils from southern Australia." Australian Systematic Botany 22, no. 3 (2009): 219. http://dx.doi.org/10.1071/sb08050.
Full textAbstract:
We present evidence that fossil leaves from an early Eocene estuarine mudstone deposit at Lowana Road in western Tasmania include the oldest records of the extant monocot genus, Ripogonum (Ripogonaceae). These fossils are similar to the extant eastern Australian and Papua New Guinean R. album R.Br. and New Zealand R. scandens J.R. et G.Forst., and are described as a new species, R. tasmanicum Conran, R.J.Carp. & G.J.Jord. The venation, cuticular and other leaf features of this fossil are included in a morphology-based phylogenetic analysis for the genus, and character evolution is discussed in relation to the ecology of the extant species and the palaeoenvironments of known Ripogonaceae fossil sites. The fossil (albeit on leaf characters) was placed close to the base of a black-fruited, Australian endemic Ripogonum clade. This suggests that the family have a long and conservative evolutionary history in association with moist forests, with the fossil locality showing palaeoclimate similar to the environments that most Ripogonum species still occupy today.
23
Wagreich, Michael, Benjamin Sames, Malcolm Hart, and Ismail O. Yilmaz. "An introduction to causes and consequences of Cretaceous sea-level changes (IGCP 609)." Geological Society, London, Special Publications 498, no. 1 (November 19, 2019): 1–8. http://dx.doi.org/10.1144/sp498-2019-156.
Full textAbstract:
AbstractThe International Geoscience Programme Project IGCP 609 addressed correlation, causes and consequences of short-term sea-level fluctuations during the Cretaceous. Processes causing several ka to several Ma (third- to fourth-order) sea-level oscillations during the Cretaceous are so far poorly understood. IGCP 609 proved the existence of sea-level cycles during potential ice sheet-free greenhouse to hothouse climate phases. These sea-level fluctuations were most probably controlled by aquifer-eustasy that is altering land-water storage owing to groundwater aquifer charge and discharge. The project investigated Cretaceous sea-level cycles in detail in order to differentiate and quantify both short- and long-term records based on orbital cyclicity. High-resolution sea-level records were correlated to the geological timescale resulting in a hierarchy of sea-level cycles in the longer Milankovitch band, especially in the 100 ka, 405 ka, 1.2 Ma and 2.4 Ma range. The relation of sea-level highs and lows to palaeoclimate events, palaeoenvironments and biota was also investigated using multiproxy studies. For a hothouse Earth such as the mid-Cretaceous, humid–arid climate cycles controlling groundwater-related sea-level change were evidenced by stable isotope data, correlation to continental lake-level records and humid–arid weathering cycles.
24
Chi, Changting, Yanyan Tian, Zhu Zhou, Lu Lu, Junping Wang, and Mingjian Wei. "Palaeoclimate and palaeoenvironmental evolution during the late Pliocene (3.04–2.88 Ma) based on pollen records from the Yinchuan Basin, Northwest China." Quaternary International 598 (October 2021): 15–23. http://dx.doi.org/10.1016/j.quaint.2021.04.036.
Full text
25
Seguin, Joana, Pavlos Avramidis, Annette Haug, Torben Kessler, Arndt Schimmelmann, and Ingmar Unkel. "Reconstruction of palaeoenvironmental variability based on an inter-comparison of four lacustrine archives on the Peloponnese (Greece) for the last 5000 years." E&G Quaternary Science Journal 69, no. 2 (October 13, 2020): 165–86. http://dx.doi.org/10.5194/egqsj-69-165-2020.
Full textAbstract:
Abstract. A high quantity of well-dated, high-resolution, continuous geoarchives is needed to connect palaeoenvironmental reconstructions with socio-environmental and cultural transformations in a geographically heterogeneous region such as southern Greece. However, detailed and continuous palaeoclimatic and palaeoenvironmental archives from the NE Peloponnese are still sparse. Here, we present two new palaeolake archives of Pheneos and Kaisari covering the last 10 500 and 6500 years, respectively. For the last 5000 years, we compare them with sediment records from adjacent Lake Stymphalia and the Asea valley by applying the same set of sedimentological, geochemical, and statistical analyses to all four lacustrine archives. Continuous geochemical X-ray fluorescence (XRF) core scanning records provide evidence for hydrological variations and environmental changes since the Early Helladic period (5050 BP), the beginning of the Bronze Age in Greece. We hereby focus on different spatial scales to estimate the validity range of the proxy signals. Ten elements were selected (Al, Si, K, Ca, Ti, Mn, Fe, Rb, Sr, Zr) for a principal component analysis. The clr(Ca∕Ti) was chosen as the most meaningful proxy, reflecting varying input of carbonaceous vs. clastic input, which may be linked to changes in the hydrological conditions. Our results show phases when permanent lake water bodies existed (ca. 5000–3600 cal BP) as well as phases with periodic desiccation of the lakes during younger times. While Pheneos and Kaisari show a drying trend during the transition phase from the Late Helladic period to the Proto-Geometric period (ca. 3200–2800 cal BP), Stymphalia and Asea show a rather short dry peak around 3200 cal BP followed by a wetter phase. Although all our geoarchives show evidence for drier phases, their timing and duration display considerable site-to-site differences which may be explained by site-specific responses in individual ecosystems. Age uncertainties, however, may likewise explain some deviations, as the dating is based on bulk sediment samples including potential unknown reservoir effects. The high regional geographical diversity within the Peloponnese combined with the dating challenges in the limestone-rich area and the variation in our data testify that any hypothetical mono-causal connection between palaeoenvironmental changes in a single geoarchive and contemporaneous societal transformations across the Peloponnese would be an oversimplification.
26
Wheeler, Alexander, and Annette E. Götz. "Palynofacies patterns of the Highveld coal deposits (Karoo Basin, South Africa): Clues to reconstruction of palaeoenvironment and palaeoclimate." Acta Palaeobotanica 56, no. 1 (June 1, 2016): 3–15. http://dx.doi.org/10.1515/acpa-2016-0004.
Full textAbstract:
Abstract The early Permian represents a crucial period of climate change in Gondwana. This climate signature is captured in the palynological record that represents the floral assemblage of the region. Palynofacies analysis of the No. 2 Coal Seam of the Highveld Coalfield provides a high-resolution picture of this climatic shift, as well as detailing the vegetation patterns and local environments. Core samples taken from two localities were studied with respect to the characteristics of the plant debris and the palynomorph assemblages to differentiate between regional and local signatures. At both of the sampling localities, the No. 2 Coal Seam is split into a Lower Coal Seam and an Upper Coal Seam by a siltstone and a sandstone intraseam parting, respectively. The uneven palaeotopography and distal depositional environment of the Highveld Coalfield distinguish it from the northern Witbank Coalfield as a river-dominated delta plain, with differences in the palaeoenvironment at each locality. Results from the Lower Coal Seam indicate a fern-dominated lowland and conifer-dominated upland. This gives way to a Glossopteris-dominated lowland and a diverse gymnospermous assemblage in the upland of the Upper Coal Seam. This change in floral composition is also observed in the adjacent Witbank Coalfield and is likely caused by climate amelioration related to the movement of Gondwana away from the South Pole.
27
Dabkowski, Julie, Jitka Frodlová, Michal Hájek, Petra Hájková, Libor Petr, Denis Fiorillo, Lydie Dudová, and Michal Horsák. "A complete Holocene climate and environment record for the Western Carpathians (Slovakia) derived from a tufa deposit." Holocene 29, no. 3 (December 19, 2018): 493–504. http://dx.doi.org/10.1177/0959683618816443.
Full textAbstract:
Calcareous tufas are great archives of geochemical information for the reconstruction of past climate. Their importance increases in the regions where other proxies are rare, such as Western Carpathians. Here, we present the first whole-Holocene palaeoclimatic reconstruction for this region based on geochemical proxies. We analysed δ18O, δ13C and Mg/Ca ratio on tufa calcite of the Mituchovci site (White Carpathian Mountains, W Slovakia) and compared these with pollen, plant macrofossil and mollusc data. According to δ18O, two distinct thermal maxima occurred in the region, around 11.4 ka and between 7.3 and 6.9 ka BP. According to δ13C and Mg/Ca ratio, a steep increase in moisture and rainfall took place around 8.5 ka cal. BP, preceded by a cold and dry event. These events are well reflected in the biotic proxies and are suggested also by other palaeoenvironmental studies from the Carpathians. We found some later fluctuations, with dry and warm Bronze Age (ca. 3.6 ka cal. BP), cold and wet Urnfield period (ca. 2.8 ka cal. BP), warm Roman period (ca. 2 ka cal. BP) and cold but humid Migration period (ca. 1.5 ka cal. BP). We observed extreme abruptness and amplitude of the variation in all geochemical proxies in the last 500 years, when biotic proxies imply a very intense human deforestation. Land-use changes may have altered both the temperature regime in the studied fen and the carbon cycle in the recharge area.
28
Tadros, Carol V., Pauline C. Treble, Andy Baker, Ian Fairchild, Stuart Hankin, Regina Roach, Monika Markowska, and Janece McDonald. "ENSO–cave drip water hydrochemical relationship: a 7-year dataset from south-eastern Australia." Hydrology and Earth System Sciences 20, no. 11 (November 17, 2016): 4625–40. http://dx.doi.org/10.5194/hess-20-4625-2016.
Full textAbstract:
Abstract. Speleothems (cave deposits), used for palaeoenvironmental reconstructions, are deposited from cave drip water. Differentiating climate and karst processes within a drip-water signal is fundamental for the correct identification of palaeoenvironmental proxies and ultimately their interpretation within speleothem records. We investigate the potential use of trace element and stable oxygen-isotope (δ18O) variations in cave drip water as palaeorainfall proxies in an Australian alpine karst site. This paper presents the first extensive hydrochemical and δ18O dataset from Harrie Wood Cave, in the Snowy Mountains, south-eastern (SE) Australia. Using a 7-year long rainfall δ18O and drip-water Ca, Cl, Mg / Ca, Sr / Ca and δ18O datasets from three drip sites, we determined that the processes of mixing, dilution, flow path change, carbonate mineral dissolution and prior calcite precipitation (PCP) accounted for the observed variations in the drip-water geochemical composition. We identify that the three monitored drip sites are fed by fracture flow from a well-mixed epikarst storage reservoir, supplied by variable concentrations of dissolved ions from soil and bedrock dissolution. We constrained the influence of multiple processes and controls on drip-water composition in a region dominated by El Niño–Southern Oscillation (ENSO). During the El Niño and dry periods, enhanced PCP, a flow path change and dissolution due to increased soil CO2 production occurred in response to warmer than average temperatures in contrast to the La Niña phase, where dilution dominated and reduced PCP were observed. We present a conceptual model, illustrating the key processes impacting the drip-water chemistry. We identified a robust relationship between ENSO and drip-water trace element concentrations and propose that variations in speleothem Mg / Ca and Sr / Ca ratios may be interpreted to reflect palaeorainfall conditions. These findings inform palaeorainfall reconstruction from speleothems regionally and provide a basis for palaeoclimate studies globally, in regions where there is intermittent recharge variability.
29
Mingram, Jens, Georg Schettler, Norbert Nowaczyk, Xiangjun Luo, Houyuan Lu, Jiaqi Liu, and Jörg F. W. Negendank. "The Huguang maar lake—a high-resolution record of palaeoenvironmental and palaeoclimatic changes over the last 78,000 years from South China." Quaternary International 122, no. 1 (January 2004): 85–107. http://dx.doi.org/10.1016/j.quaint.2004.02.001.
Full text
30
Schröder, Tabea, José Antonio López-Sáez, Jasmijn van’t Hoff, and Klaus Reicherter. "Unravelling the Holocene environmental history of south-western Iberia through a palynological study of Lake Medina sediments." Holocene 30, no. 1 (July 31, 2019): 13–22. http://dx.doi.org/10.1177/0959683619865590.
Full textAbstract:
Lake Medina is a small, shallow and endorheic salt lake sensitive to climate variation in south-western Spain, close to Cádiz in western Andalusia. It is located in an evaporitic and karstic environment, and a saline lake affected by highly seasonal precipitation and evaporation. Geochemical and mineralogical data of core CO1313 combined with a robust age model show variation that contributes to the understanding of palaeoenvironmental and palaeoclimatic change. This study shows a pollen record that has been conducted on core CO1313, together with charcoal and non-pollen palynomorph analyses. The environmental and climatological history reconstruction of Lake Medina starts in early Holocene times (at 9.5 cal. ka BP) and shows intensified pasture and land use during middle-Holocene times as well as the 8.2 and 4.2 cal. ka BP abrupt climate events. Oxidation of plant remnants and resulting non-preservation at certain times reinforces the hypothesis of intense climate effects on vegetation during the 4.2 cal. ka BP climate event. Yet, oxidation of plant residues during other episodes shows other periods that were also affected by reduced precipitation. From around 2 cal. ka BP onwards, a recent trend towards aridification and enforced seasonality was detected.
31
Diniz, Débora, and Svetlana Medeanic. "Palynomorph Records from the Core of Rio Grande Cone, Brazil: Approaches for Palaeoenvironmental and Palaeoclimatic Reconstructions in the Middle Holocene." Journal of Coastal Research 292 (November 2013): 1351–60. http://dx.doi.org/10.2112/jcoastres-d-11-00121.1.
Full text
32
Novenko, Elena Yu, Andrey N. Tsyganov, Kirill V. Babeshko, Richard J. Payne, Jinlin Li, Yuri A. Mazei, and Alexander V. Olchev. "Climatic moisture conditions in the north-west of the Mid-Russian Upland during the Holocene." GEOGRAPHY, ENVIRONMENT, SUSTAINABILITY 12, no. 4 (December 31, 2019): 188–202. http://dx.doi.org/10.24057/2071-9388-2018-62.
Full textAbstract:
This study aimed to reconstruct the climatic moisture conditions of the Mid- Russian Upland through the Holocene. Surface moisture conditions in the study region were inferred from published pollen records from the Klukva peatland, in the north-west of the Mid-Russian Upland. Three climatic indices were derived from previously- published reconstructions of mean annual temperature and precipitation: the Climate Moisture Index, the Aridity Index and the Budyko Dryness Index. A simple modeling approach to reconstruct annual potential evapotranspiration and net radiation was developed and used to estimate the indices for different periods of the Holocene. The moisture indices were compared with independent proxies of climate moisture such as peatland surface wetness, reconstructed from testate amoebae and regional fire activity, reconstructed from charcoal. Results show that the surface moisture conditions in the study region were characterized by large variability. Periods of mild temperature and moderately wet conditions were followed by dry periods, which resulted in significant changes in palaeoenvironments. The method developed for calculation of potential evapotranspiration and indices of surface moisture conditions could be a useful tool for climate reconstructions. Our results demonstrate the detailed and nuanced palaeoclimate data which can be derived from pollen data.
33
Leicher, Niklas, Giovanni Zanchetta, Roberto Sulpizio, Biagio Giaccio, Bernd Wagner, Sebastien Nomade, Alexander Francke, and Paola Del Carlo. "First tephrostratigraphic results of the DEEP site record from Lake Ohrid (Macedonia and Albania)." Biogeosciences 13, no. 7 (April 13, 2016): 2151–78. http://dx.doi.org/10.5194/bg-13-2151-2016.
Full textAbstract:
Abstract. A tephrostratigraphic record covering the Marine Isotope Stages (MIS) 1–15 was established for the DEEP site record of Lake Ohrid (Macedonia and Albania). Major element analyses (energy dispersive spectroscopy (EDS) and wavelength-dispersive spectroscopy (WDS)) were carried out on juvenile fragments extracted from 12 tephra layers (OH-DP-0115 to OH-DP-2060). The geochemical analyses of the glass shards of all of these layers suggest an origin in the Italian volcanic provinces. They include the Y-3 (OH-DP-0115, 26.68–29.42 ka cal BP), the Campanian Ignimbrite–Y-5 (OH-DP-0169, 39.6 ± 0.1 ka), and the X-6 (OH-DP-0404, 109 ± 2 ka) from the Campanian volcanoes, the P-11 of Pantelleria (OH-DP-0499, 133.5 ± 2 ka), the Vico B (OH-DP-0617, 162 ± 6 ka) from the Vico volcano, the Pozzolane Rosse (OH-DP-1817, 457 ± 2 ka) and the Tufo di Bagni Albule (OH-DP-2060, 527 ± 2 ka) from the Colli Albani volcanic district, and the Fall A (OH-DP-2010, 496 ± 3 ka) from the Sabatini volcanic field. Furthermore, a comparison of the Ohrid record with tephrostratigraphic records of mid-distal archives related to the Mediterranean area allowed the recognition of the equivalents of other less known tephra layers, such as the TM24a–POP2 (OH-DP-0404, 102 ± 2 ka) recognized in the Lago Grande di Monticchio and the Sulmona Basin, the CF-V5–PRAD3225 (OH-DP-0624, ca. 163 ± 22 ka) identified in the Campo Felice Basin and the Adriatic Sea, the SC5 (OH-DP-1955, 493.1 ± 10.9 ka) recognized in the Mercure Basin, and the A11/12 (OH-DP-2017, 511 ± 6 ka) sampled at the Acerno Basin, whose specific volcanic sources are still poorly constrained. Additionally, one cryptotephra (OH-DP-0027) was identified by correlation of the potassium X-ray flourescence (XRF) intensities from the DEEP site with those from a short core of a previous study from Lake Ohrid. In these cores, a maximum in potassium is caused by glass shards, which were correlated with the Mercato tephra (8.43–8.63 ka cal BP) from Somma–Vesuvius. The tephrostratigraphic work presented here allows, for the first time, the extension of a consistent part of the Middle Pleistocene tephrostratigraphy of Italian volcanoes as far as the Balkans. The establishment of the tephrostratigraphic framework for the Lake Ohrid record provides important, independent tie points for the age–depth model of the DEEP site sequence, which is a prerequisite for palaeoclimatic and palaeoenvironmental reconstructions. Furthermore, this age–depth model will help to improve and re-evaluate the chronology of other, both undated and dated tephra layers from other records. Thus, the Lake Ohrid record may potentially become the template for the central Mediterranean tephrostratigraphy, especially for the hitherto poorly known and explored lower Middle Pleistocene period.
34
Pokharia, Anil K., Jeewan Singh Kharakwal, Shalini Sharma, Michael Spate, Deepika Tripathi, Ashok Priyadarshan Dimri, Xinyi Liu, et al. "Variable monsoons and human adaptations: Archaeological and palaeoenvironmental records during the last 1400 years in north-western India." Holocene 30, no. 9 (May 6, 2020): 1332–44. http://dx.doi.org/10.1177/0959683620919976.
Full textAbstract:
We present the first systematic evaluation of the relationship between the archaeological and palaeoclimatic record from north-western India during the past millennium, from the urban site of Chandravati. The rarity of Medieval sites, systematic excavations and multi-disciplinary work in the subcontinent obscure the impact of two distinct climate anomalies − the ‘Medieval Warm Period’ (‘MWP’, 740 − 1150 CE), followed by the ‘Little Ice Age’ (‘LIA’, 1350 − 1850 CE). The finds from the archaeological site indicate the presence of winter and summer crops, suggesting the region was likely warm and mild humid during pre-Medieval period (ca. 600 − 800 CE). During Medieval times (between ca. 800 − 1300 CE), a diversification of the crop assemblage suggests that the region was under a warm and humid climate, corresponding to the ‘MWP’, driving increased monsoon precipitation. During the post-Medieval period (ca. 1350 − 1800 CE), drought-resistant millets and other summer pulse crops indicate the region probably experienced weak SW monsoon precipitation coinciding with globally recognised ‘LIA’. These interpretations are supported through phytolith data from the archaeological deposit broadly indicating two phases, the first being a period of diversified agricultural/anthropogenic activity (ca. 600 − 1350 CE), followed by a period dominated by drought-resistant crops (ca. 1350 − 1800 CE). Pollen data from a proximal lake corroborate the warm and humid phase ca. 800 − 1400 CE, with strong representation of warm−humid favouring tropical forest taxa, followed by non-arboreal indicators of a drier more open landscape ca. 1500 − 1800 CE. These environmental changes may have combined with other historic and institutional factors that led to the ultimate abandonment of the city. These changing cropping patterns, vegetation and cultural developments provide insight into past human response to climate change as well as important lessons for modern societies in exploring sustainable agricultural strategies to future climate change.
35
Guimarães, José Tasso Felix, Tarcísio Magevski Rodrigues, Luiza Santos Reis, Mariana Maha Jana Costa de Figueiredo, Delmo Fonseca da Silva, Ronnie Alves, Tereza Cristina Giannini, et al. "Modern pollen rain as a background for palaeoenvironmental studies in the Serra dos Carajás, southeastern Amazonia." Holocene 27, no. 8 (January 18, 2017): 1055–66. http://dx.doi.org/10.1177/0959683616683260.
Full textAbstract:
Several alternative interpretations of the pollen records of lake sediments in the Amazonia may arise due to a lack of understanding of the modern environments, mainly related to pollen–vegetation relationship. Therefore, in this work, we studied the modern pollen rain in sediments of the Amendoim Lake, plateaus of the Serra Sul dos Carajás, southeastern Amazonia. This study indicates the predominance of pollen grains from forest formation (ombrophilous forests and capão florestal) over montane savanna in the lake sediments, despite the fact that montane savanna occupies ~90% of the drainage basin. Additionally, these sediments reflect stronger signal of pollen from ombrophilous forests that occur in the slopes of the plateau. Important components of montane savanna such as Vellozia and Cereus were not observed in the modern pollen rain, which may be related to their shorter flowering periods restricted to the beginning of wetter conditions. The absence of Sacoglottis, Trichilia, Clusia, Emmotum, Guapira and Simarouba in the pollen rain is likely associated with different pollination strategy. The occurrence of windblown pollen of Alchornea, Pseudolmedia, Ilex and Cecropia, which are found from low to highlands of the Carajás region, reinforces a regional vegetation signal in sediments. Several plants from the studied site have been improperly described, according to taxonomy and ecology. For example, the current occurrence of Ilex and Styrax in the study site clearly suggests that they cannot be used as indicators of colder palaeoclimate conditions, as previously described. In addition, Poaceae can be found in drier to wetter substrate conditions, and abundance of their pollen grains in lakes can significantly vary according to relief morphology and cannot indicate palaeovegetation openness. Therefore, this work is a good background for further palaeobotany studies for this region.
36
LÖWEMARK, LUDVIG, HUI-LING LIN, and MICHAEL SARNTHEIN. "Temporal variations of the trace fossil Zoophycos in a 425 ka long sediment record from the South China Sea: implications for the ethology of the Zoophycos producer." Geological Magazine 143, no. 1 (December 2, 2005): 105–14. http://dx.doi.org/10.1017/s0016756805001408.
Full textAbstract:
A 425 ka long record from piston core GIK17925-3 taken in the northeastern South China Sea was used to study the environmental conditions controlling the distribution of the Zoophycos trace fossil. The 12 m long core offers a unique opportunity to study the response of the Zoophycos-producing animal to environmental variations over four glacial–interglacial cycles. The trace fossils show a strong glacial to interglacial variation in their abundance with a special preference for intervals with low sedimentation rates. Additional X-ray radiograph studies of piston cores from the Southeast Asian Marginal Seas show that the trace fossil Zoophycos is widespread in slope and deep-marine sediments, with the highest abundances encountered in low sedimentation rate settings. The preference of the Zoophycos producer for low sedimentation rates in a setting with strong seasonal fluctuations in food supply due to the shift between winter and summer monsoons, is interpreted to be the result of a cache-model behaviour, where food is collected during rich times and squirrelled away for poor times. Core GIK17925-3 also offers an opportunity to assess the impact of Zoophycos bioturbation on various palaeoenvironmental proxies. In this core, more than 30 % of the measured data points were more or less strongly affected by Zoophycos bioturbation. Together with the widespread occurrence this percentage indicates that Zoophycos may pose a serious threat to palaeoclimatic reconstructions in cores from low to moderate sedimentation rate sites.
37
Szymanek, Marcin, Krzysztof Bińka, and Jerzy Nitychoruk. "Stable18O and13C isotope records ofViviparus diluvianus(Kunth, 1865) shells from Holsteinian (MIS 11) lakes of eastern Poland as palaeoenvironmental and palaeoclimatic proxies." Boreas 45, no. 1 (September 7, 2015): 109–21. http://dx.doi.org/10.1111/bor.12137.
Full text
38
Adamson, Kathryn, Ian Candy, and Liz Whitfield. "Coupled micromorphological and stable isotope analysis of Quaternary calcrete development." Quaternary Research 84, no. 2 (September 2015): 272–86. http://dx.doi.org/10.1016/j.yqres.2015.05.002.
Full textAbstract:
Pedogenic calcretes are widespread in arid and semi-arid regions. Using calcrete profiles from four river terraces of the Rio Alias in southeast Spain, this study explores the potential of using detailed micromorphological and stable isotopic analysis to more fully understand the impacts of Quaternary environmental change on calcrete development. The four profiles increase in carbonate complexity with progressive age, reflecting calcretisation over multiple glacial–interglacial cycles since MIS 9 (c. 300 ka). Calcrete profiles contain a mixture of Alpha (non-biogenic) and Beta (biogenic) microfabrics. Alpha fabrics have higher δ13C and δ18O values. The profiles contain a range of crystal textures, but there is little difference between the δ13C and δ18O values of spar, microspar, and micrite cements. Strong positive covariance between δ13C and δ18O suggests that both isotopes are responding to the same environmental parameter, which is inferred to be relative aridity. The study reveals that the detailed co-analysis of calcrete micromorphology and stable isotope signatures can allow patterns of calcrete formation to be placed into a wider palaeoclimatic context. This demonstrates the potential of this technique to more reliably constrain the palaeoenvironmental significance of secondary carbonates in dryland settings where other proxy records may be poorly preserved.
39
MACKENSEN, ANDREAS. "Changing Southern Ocean palaeocirculation and effects on global climate." Antarctic Science 16, no. 4 (November 30, 2004): 369–86. http://dx.doi.org/10.1017/s0954102004002202.
Full textAbstract:
Southern Ocean palaeocirculation is clearly related to the formation of a continental ice sheet on Antarctica and the opening of gateways between Antarctica and the Australian and South American continents. Palaeoenvironmental proxy records from Southern Ocean sediment cores suggest ice growth on Antarctica beginning by at least 40 million years (Ma) ago, and the opening of Tasmania–Antarctic and Drake Passages to deep-water flow around 34 and 31 ± 2 Ma, respectively. So, the Eocene/Oligocene transition appears to mark the initiation of the Antarctic Circumpolar Current and thus the onset of thermal isolation of Antarctica with a first major ice volume growth on East Antarctic. There is no evidence for a significant cooling of the deep ocean associated with this rapid (< 350 000 years) continental ice build-up. After a long phase with frequent ice sheets growing and decaying, in the middle Miocene at about 14 Ma, a re-establishment of an ice sheet on East Antarctica and the Pacific margin of West Antarctica was associated with an increased southern bottom water formation, and a slight cooling of the deep ocean, but with no permanent drop in atmospheric pCO2. During the late Pleistocene on orbital time scales a temporal correlation between changes in atmospheric pCO2 and proxy records of deep ocean temperatures, continental ice volume, sea ice extension, and deep-water nutrient contents is documented. I discuss hypotheses that call for a dominant control of glacial to interglacial atmospheric pCO2 variations by Southern Ocean circulation dynamics. Millennial to centennial climate variability is a global feature, but there is contrasting evidence from various palaeoclimate archives that indicate both interhemispheric synchrony and asynchrony. The role of the Southern Ocean, however, in triggering or modulating climate variability on these time scales only recently received some attention and is not yet adequately investigated.
40
McCormack, Jeremy, Finn Viehberg, Derya Akdemir, Adrian Immenhauser, and Ola Kwiecien. "Ostracods as ecological and isotopic indicators of lake water salinity changes: the Lake Van example." Biogeosciences 16, no. 10 (May 20, 2019): 2095–114. http://dx.doi.org/10.5194/bg-16-2095-2019.
Full textAbstract:
Abstract. Ostracods are common lacustrine calcitic microfossils. Their faunal assemblage and morphological characteristics are important ecological proxies, and their valves are archives of geochemical information related to palaeoclimatic and palaeohydrological changes. In an attempt to assess ostracod ecology (taxonomic diversity and valve morphology) combined with valve geochemistry (δ18O and δ13C) as palaeosalinity indicators, we analysed sedimentary material from the International Continental Scientific Drilling Program (ICDP) Ahlat Ridge site from a terminal and alkaline lake, Lake Van (Turkey), covering the last 150 kyr. Despite a low species diversity, the ostracod faunal assemblage reacted sensitively to changes in the concentration of total dissolved salts in their aquatic environment. Limnocythere inopinata is present throughout the studied interval, while Limnocythere sp. A is restricted to the Last Glacial period and related to increased lake water salinity and alkalinity. The presence of species belonging to the genus Candona is limited to periods of lower salinity. Valves of Limnocytherinae species (incl. L. inopinata) display nodes (hollow protrusions) during intervals of increased salinity. Both the number of noded valves and the number of nodes per valve appear to increase with rising salinity, suggesting that node formation is related to hydrological changes (salinity and/or alkalinity). In contrast to Lake Van's bulk δ18O record, the δ18O values of ostracod valves do record relative changes of the lake volume, with lower values during high lake level periods. The δ13C values of different species reflect ostracod habitat preferences (i.e. infaunal vs. epifaunal) but are less sensitive to hydrological changes. However, combined with other proxies, decreasing Holocene δ13C values may indicate a freshening of the lake water compared to the low lake level during the Last Glacial period. The Lake Van example underscores the significance and value of coupling ostracod ecology and valve geochemistry in palaeoenvironmental studies of endorheic lake basins.
41
Ackerley, Duncan, Jessica Reeves, Cameron Barr, Helen Bostock, Kathryn Fitzsimmons, Michael-Shawn Fletcher, Chris Gouramanis, et al. "Evaluation of PMIP2 and PMIP3 simulations of mid-Holocene climate in the Indo-Pacific, Australasian and Southern Ocean regions." Climate of the Past 13, no. 11 (November 24, 2017): 1661–84. http://dx.doi.org/10.5194/cp-13-1661-2017.
Full textAbstract:
Abstract. This study uses the simplified patterns of temperature and effective precipitation approach from the Australian component of the international palaeoclimate synthesis effort (INTegration of Ice core, MArine and TErrestrial records – OZ-INTIMATE) to compare atmosphere–ocean general circulation model (AOGCM) simulations and proxy reconstructions. The approach is used in order to identify important properties (e.g. circulation and precipitation) of past climatic states from the models and proxies, which is a primary objective of the Southern Hemisphere Assessment of PalaeoEnvironment (SHAPE) initiative. The AOGCM data are taken from the Paleoclimate Modelling Intercomparison Project (PMIP) mid-Holocene (ca. 6000 years before present, 6 ka) and pre-industrial control (ca. 1750 CE, 0 ka) experiments. The synthesis presented here shows that the models and proxies agree on the differences in climate state for 6 ka relative to 0 ka, when they are insolation driven. The largest uncertainty between the models and the proxies occurs over the Indo-Pacific Warm Pool (IPWP). The analysis shows that the lower temperatures in the Pacific at around 6 ka in the models may be the result of an enhancement of an existing systematic error. It is therefore difficult to decipher which one of the proxies and/or the models is correct. This study also shows that a reduction in the Equator-to-pole temperature difference in the Southern Hemisphere causes the mid-latitude westerly wind strength to reduce in the models; however, the simulated rainfall actually increases over the southern temperate zone of Australia as a result of higher convective precipitation. Such a mechanism (increased convection) may be useful for resolving disparities between different regional proxy records and model simulations. Finally, after assessing the available datasets (model and proxy), opportunities for better model–proxy integrated research are discussed.
42
Deutz, P., I. P. Montañez, H. C. Monger, and J. Morrison. "Erratum to “Derivation of a palaeoenvironmental record from pedogenic carbonates in buried and relict Quaternary soils, Rio Grande Rift, New Mexico” [Palaeogeogr., Palaeoclimatol., Palaeoecol. 166 (2001) 293–317]." Palaeogeography, Palaeoclimatology, Palaeoecology 171, no. 1-2 (July 2001): 85–87. http://dx.doi.org/10.1016/s0031-0182(01)00260-7.
Full text
43
Solotchina, E. P., A. A. Prokopenko, A. N. Vasilevsky, V. M. Gavshin, M. I. Kuzmin, and D. F. Williams. "Simulation of XRD patterns as an optimal technique for studying glacial and interglacial clay mineral associations in bottom sediments of Lake Baikal." Clay Minerals 37, no. 1 (March 2002): 105–19. http://dx.doi.org/10.1180/0009855023710021.
Full textAbstract:
AbstractA new method is proposed for modelling complex X-ray diffraction patterns effectively. The method is based on the calculation of the interference function of the onedimensional disordered crystals with finite thickness. First, we calculated the diffraction effects from structures of individual mineral phases with different layer defects modelled according to the Reynolds’ algorithm. To fit the theoretical to the observed XRD patterns more accurately, we then used a specially developed optimization procedure. This iterative procedure selects the optimal set of chemical and structural parameters (probability and domain size) and yields consistent solutions.The composition of the clay component in bottom sediments of Lake Baikal relates strongly to glacial/interglacial climate cyclicity. Besides changes in the relative abundance of illite and illite/ smectites between glacial and interglacial periods, significant differences are observed in the crystal chemistries and structures of layered minerals. A change from chlorite during glacial periods to chlorite-smectite during interglacials is probably indicative of the weathering processes in the watershed. Changes in the degree of ordering, in domain size and grain-size distribution of illitesmectites imply differences in genesis of this mineral phase in different palaeoenvironments. These findings further strengthen the case for using clay minerals in the sedimentary record of Lake Baikal as palaeoclimate indicators.One of our findings was that none of the fractions separated by Stokes’ settling is representative of the bulk sample for either the glacial or interglacial intervals. For the interglacial sample, illitesmectite was concentrated in the <2 μm fraction whereas, for the glacial sample, most of illitesmectite is contained in the <1 μm fraction. The selective use of one fraction is yet another potential source of uncontrolled errors that has to be avoided. We suggest using X-ray patterns of bulk samples as a preferred method of analysis of Lake Baikal (and other) sediments.
44
Vansteenberge, Stef, Niels J. de Winter, Matthias Sinnesael, Sophie Verheyden, Steven Goderis, Stijn J. M. Van Malderen, Frank Vanhaecke, and Philippe Claeys. "Reconstructing seasonality through stable-isotope and trace-element analyses of the Proserpine stalagmite, Han-sur-Lesse cave, Belgium: indications for climate-driven changes during the last 400 years." Climate of the Past 16, no. 1 (January 16, 2020): 141–60. http://dx.doi.org/10.5194/cp-16-141-2020.
Full textAbstract:
Abstract. Fast-growing speleothems allow for the reconstruction of palaeoclimate down to a seasonal scale. Additionally, annual lamination in some of these speleothems yields highly accurate age models for these palaeoclimate records, making these speleothems valuable archives for terrestrial climate. In this study, an annually laminated stalagmite from the Han-sur-Lesse cave (Belgium) is used to study the expression of the seasonal cycle in northwestern Europe during the Little Ice Age. More specifically, two historical 12-year-long growth periods (ca. 1593–1605 CE and 1635–1646 CE) and one modern growth period (1960–2010 CE) are analysed on a sub-annual scale for their stable-isotope ratios (δ13C and δ18O) and trace-element (Mg, Sr, Ba, Zn, Y, Pb, U) contents. Seasonal variability in these proxies is confirmed with frequency analysis. Zn, Y and Pb show distinct annual peaks in all three investigated periods related to annual flushing of the soil during winter. A strong seasonal in-phase relationship between Mg, Sr and Ba in the modern growth period reflects a substantial influence of enhanced prior calcite precipitation (PCP). In particular, PCP occurs during summers when recharge of the epikarst is low. This is also evidenced by earlier observations of increased δ13C values during summer. In the 17th century intervals, there is a distinct antiphase relationship between Mg, Sr and Ba, suggesting that processes other than PCP, i.e. varying degrees of incongruent dissolution of dolomite, eventually related to changes in soil activity and/or land-use change are more dominant. The processes controlling seasonal variations in Mg, Sr and Ba in the speleothem appear to change between the 17th century and 1960–2010 CE. The Zn, Y, Pb, and U concentration profiles; stable-isotope ratios; and morphology of the speleothem laminae all point towards increased seasonal amplitude in cave hydrology. Higher seasonal peaks in soil-derived elements (e.g. Zn and Y) and lower concentrations of host-rock-derived elements (e.g. Mg, Sr, Ba) point towards lower residence times in the epikarst and higher flushing rates during the 17th century. These observations reflect an increase in water excess above the cave and recharge of the epikarst, due to a combination of lower summer temperatures and increased winter precipitation during the 17th century. This study indicates that the transfer function controlling Mg, Sr and Ba seasonal variability varies over time. Which process is dominant – either PCP, soil activity or dolomite dissolution – is clearly climate driven and can itself be used as a palaeoenvironment proxy.
45
Bañuls-Cardona, Sandra, Patricia Martín Rodríguez, Juan Manuel López-García, Juan Ignacio Morales, Gloria Cuenca-Bescós, and Josep María Vergès. "Human impact on small-mammal diversity during the middle- to late-Holocene in Iberia: The case of El Mirador cave (Sierra de Atapuerca, Burgos, Spain)." Holocene 27, no. 8 (January 18, 2017): 1067–77. http://dx.doi.org/10.1177/0959683616683257.
Full textAbstract:
The human impact on the environment in the Holocene has usually been characterized on the basis of palaeobotanical records, but attempts to distinguish the anthropogenic impact from natural events in landscape evolution have been the subject of much debate in recent years. The aim of this paper is to analyse small-mammal diversity and the presence of synanthropic species, whose small size makes them more sensitive to any changes in their environment that may occur. This study has allowed us to characterize palaeoclimatic and palaeoenvironmental changes, recording small changes whether resulting from a human influence or otherwise. Our object of study is El Mirador cave, which has a sequence with a well-documented human occupation extending from 7200 to 3000 cal. BP. The study has led us to differentiate two phases. In one phase, we can see small changes in diversity related to climatic oscillations from ca. 7200 to 6800 cal. BP, while in the second phase, lasting from ca. 6800 to 3000 cal. BP, the changes in diversity and in the assemblage of synanthropic species are associated with human economic strategies. Moreover, we distinguish which kinds of economic activity (crop and livestock farming) have influenced these changes, because some small-mammal species are influenced, positively or negatively, by environmental changes based on crop farming and animal husbandry. All this information is contrasted with other archaeological proxies, such as the large-mammal and palaeobotanical assemblages from El Mirador cave. Furthermore, this integrative analysis has made it possible to identify the existence of altered environments more generally throughout the Iberian Peninsula from ca. 6000 cal. BP. It additionally confirms the theory of low human occupation intensity in the northern Meseta and in high mountainous areas during the early Neolithic.
46
Rose, James. "Book Review: Quaternary geology of the Geneva Bay (Lake Geneva, Switzerland): sedimentary record, palaeoenvironmental and palaeoclimatic reconstruction since the last glacial cycle by Andrea Moscariello. Section des Sciences de la Terre, Universite de Geneve, Suisse, 1996. Terre and Environment, Vol. 4 (xii + 230 pp). FrS. 30. ISBN 2-940153-03-5." Journal of Quaternary Science 13, no. 1 (January 1998): 91. http://dx.doi.org/10.1002/(sici)1099-1417(199801/02)13:1<91::aid-jqs338>3.0.co;2-i.
Full text
47
Knight, J., and J. M. Fitchett. "A proposed chronostratigraphic framework for the late Quaternary of southern Africa." South African Journal of Geology, July 23, 2021. http://dx.doi.org/10.25131/sajg.124.0030.
Full textAbstract:
Abstract The principles of chronostratigraphy can inform the process of correlation between different palaeoclimate records, enabling the coherence of spatial and temporal patterns of past climates and environments to be identified based on the physical, chemical, biological and isotopic properties of individual depositional units. This study presents a chronostratigraphic framework for the late Quaternary of southern Africa, based on the integration of palaeoclimatic and palaeoenvironmental proxy data from key records across the country from the start of Marine Isotope Stage 6 (~191 ka BP) to present. The methodology adopted in this study involves, first, wiggle-matching between sufficiently long and continuous records from different regions across southern Africa, informed by radiometric age controls from individual records. Based on interpretive limitations of these records, we then integrate different geomorphic and archaeological data types in proposing successive chronostratigraphic time periods that collectively extend through the late Quaternary of southern Africa. These time periods correspond to phases in which, within them, a certain set of (relative) stable climates or environments existed in different regions of southern Africa, as recorded in different ways in different proxy records. The boundaries between successive time periods are identified where there is evidence for a significant change in the workings of the climate or environmental system as reflected in the preserved proxy record found in a certain locality. These chronostratigraphic units are interpreted as reflecting the impacts of external forcing that is of regional extent, synchronous, and are not merely an outcome of local environmental variability. These chronostratigraphic phases identified for the late Quaternary period also correspond to distinctive technological and cultural phases in the southern African archaeological record, demonstrating links between coeval climate and environmental change and phases of human evolutionary development. This chronostratigraphic approach provides both a correlative framework for understanding the varied late Quaternary records of southern Africa, and a testable hypothesis for considering the synchroneity or otherwise of different records and thus their associated forcing factors.
48
Fitchett, Jennifer M., Stefan W. Grab, Marion K. Bamford, and Anson W. Mackay. "A multi-disciplinary review of late Quaternary palaeoclimates and environments for Lesotho." South African Journal of Science Volume 112, Number 7/8 (July 27, 2016). http://dx.doi.org/10.17159/sajs.2016/20160045.
Full textAbstract:
Abstract Lesotho provides a unique context for palaeoclimatic research. The small country is entirely landlocked by South Africa, yet has considerable variation in topography, climate, and associated vegetation over an approximate east–west transect. The region has been of archaeological interest for over a century, and hosts many Early to Late Stone Age sites with occupation preceding 80 000 years before present. The eastern Lesotho highlands are of interest to periglacial and glacial geomorphologists because of their well-preserved relict landforms and contentious evidence for permafrost and niche glaciation during the late Quaternary. However, continuous proxy records for palaeoenvironmental reconstructions for Lesotho are scarce and hampered by a range of methodological shortfalls. These challenges include uncertain ages, poor sampling resolution, and proxies extracted from archaeological excavations for which there may be bias in selection. Inferences on palaeoclimates are thus based predominantly on archaeological and palaeogeomorphological evidence for discrete periods during the late Quaternary. This review paper presents a more detailed multidisciplinary synthesis of late Quaternary conditions in Lesotho. We simultaneously considered the varying data that contribute to the under-studied palaeoenvironmental record for southern Africa. The collective palaeoenvironmental data for eastern Lesotho were shown to be relatively contradictory, with considerable variations in contemporaneous palaeoclimatic conditions within the study area. We argue that although methodological challenges may contribute to this variation, the marked changes in topography result in contrasting late Quaternary palaeoenvironments. Such environments are characterised by similar contrasting microclimates and niche ecologies as are witnessed in the contemporary landscape. These spatial variations within a relatively small landlocked country are of importance in understanding broader southern African palaeoenvironmental change.
49
Stratford, D., K. Braun, and P. Morrissey. "Cave and rock shelter sediments of southern Africa: a review of the chronostratigraphic and palaeoenvironmental record from Marine Isotope Stage 6 to 1." South African Journal of Geology, August 22, 2021. http://dx.doi.org/10.25131/sajg.124.0052.
Full textAbstract:
Abstract Caves and rock shelters contribute important records to local, regional and sub-continental reconstructions of environment and climate change through the southern African Quaternary. Against a backdrop of pronounced climate change, the archaeological record of the Marine Isotope Stage 6 to 1 period in southern Africa documents a remarkable time in the behavioural and technological evolution of anatomically modern humans. Significant evidence of this evolution is represented in diverse components of the sedimentary record in caves and rock shelters in the region. We present a catalogue of published caves and rock shelters in southern Africa that preserve temporally-relevant clastic and chemical palaeoclimatic proxies in order to: (1) facilitate the integration of cave and rock shelter sedimentary data into broader, regional chronostratigraphically-correlated palaeoclimatic sequences; and (2) identify possible areas and proxies that require focused research in the future. To demonstrate the complexity of the Marine Isotope Stage 6 to 1 stratigraphic record and use of palaeoenvironmental proxies, we present three case studies representing interior and coastal contexts: Border Cave, Klasies River Mouth and Pinnacle Point. These examples aptly demonstrate the challenges of these contexts, but also the opportunities for palaeoenvironmental research in southern Africa when conducted through integrated, multidisciplinary approaches. Published records of palaeoenvironmental research from cave and rock shelter sequences in southern Africa are heavily biased to the South African coastal areas and the record is temporally and spatially fragmented. However, there are interesting patterns in the chronostratigraphic record and in the distribution of sites within the context of the geology and vegetation ecology of southern Africa that require further exploration. There are also promising techniques in stable isotope analysis that can be applied to abundant sedimentary components found in the region’s caves and rock shelters, and in its museums.
50
Sümegi, Pál, Tünde Lócskai, and Júlia Hupuczi. "Late Quaternary palaeoenvironment and palaeoclimate of the Lake Fehér (Fehér-tó) sequence at Kardoskút (South Hungary), based on preliminary mollusc records." Open Geosciences 3, no. 1 (January 1, 2011). http://dx.doi.org/10.2478/s13533-011-0007-5.
Full textAbstract:
AbstractForty (22 freshwater gastropod, 14 gastropod, 4 bivalves) species and 3428 specimens of molluscs were collected and identified from a 6.3 m sequence, obtained from a core profile, of lake and fluvial sediments at Kardoskút, South Hungary. According to changes in the molluscan fauna, six malacological-palaeoecological zones can be identified in this profile. The Quaternary malacological data from the Lake Fehér core profile suggests that the Late Pleniglacial and Early Holocene development of the molluscan fauna, and local palaeoclimatic and palaeoenvironmental conditions in this area, differed from other regions in Europe.