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1.
Julieta Massaferro Stephen J. Brooks Simon G. Haberle 《Quaternary Science Reviews》2005,24(23-24):2510-2522
We compare high-resolution pollen and chironomid records from the last 15,000 yr in Laguna Facil, southern Chile. Major vegetation and chironomid changes are recorded between ca 14,900 and 14,700 cal. yr BP. During the Lateglacial, changes in the chironomid stratigraphy lag behind changes in the pollen stratigraphy suggesting that the chironomids are responding to changes in the tree canopy or in soil chemistry brought about by vegetational development. At about 7200 cal. yr BP there is a change in the chironomid stratigraphy in advance of changes in the vegetation. This suggests that the response is to regional climatic change. The relatively close correlation of the chironomid and pollen stratigraphies with changes in charcoal concentrations also implicates the importance of fire and/or vulcanism in influencing the dynamics of forest and limnological systems. There is no clear evidence of cooling during the Younger Dryas chronozone in Laguna Facil. 相似文献
2.
M.M. Massaferro J. Massaferro G. Roman Ross A.J. Amos A. Lami 《Journal of Paleolimnology》1999,22(2):137-148
Stratigraphy of Lake El Trébol (41°S 71°W, 758 m a.s.l.) described from an 11 m long sediment core provided a continuous record of patecenvironmental changes occurred during the last 14,000 years in southern South America east of the Andes. Located in an ecotonal area within a strong humidity gradient, this lake offers a unique opportunity to develop paleolimnological studies. Using a geochemical approach that includes elemental analysis, bulk organic matter, major nutrients and pigments combined with chironomids and pollen analysis, three zones were identified in the sedimentary record of this take. The oldest one (between 680 and 1,100 cm) corresponds to the late Glacial period. During that time, clayish laminated sediments were formed in a proglacial environment. Low organic matter, biogenic silica and nitrogen contents and the absence of pigments, pollen and chironomids characterise this period. At the end of this period, ca. 14,000 yr BP, a sharp increase in phosphorus concentrations predates major changes in limnological parameters. The transition zone (between 560 and 680 cm) is related to major changes in the drainage system that started soon after ca. 14,000 yr BP and continued to ca. 10,500 yr BP. The chemical composition of the sediments was affected by an increase in physical weathering mechanisms almost coincident with the increase in the regional volcanic activity that produced suspended volcanic detritus. The increase of mainly coarser detritical components may indicate a reorganisation of the fluvial system by that time. Simultaneously, an increase in the productivity of the lake accompanied by a gradual replacement of open vegetation with Nothofagus, Poaceae and Ericaceae, by Nothofagusforest, was observed. In the last zone (between 0 and 560 cm) the productivity of Lake El Trébol achieves maximum values. The trends in geochemical and biological indicators observed at Lake El Trébol can be up to some extent, correlated to those registered in Lake Mascardi. The results support earlier paleoctimatic scenarios from southern South America. 相似文献
3.
E. Schwarz G.D. VeigaL.A. Spalletti J.L. Massaferro 《Marine and Petroleum Geology》2011,28(6):1218-1241
The Berriasian-Valanginian Springhill Formation of the Austral Basin of southern South America comprises fluvial to marine deposits. In order to interpret depositional systems and unravel the stratigraphic architecture of this unit in the southern region of the basin (Tierra del Fuego Province, Argentina), 500 m of cores combined with well-log data from 41 wells were studied. Facies associations corresponding to fluvial (A1-A6), estuarine (B1-B5) and open-marine (C1-C4) depositional environments were identified. These facies associations succeed each other vertically across the entire study area (6800 km2) forming a ∼120-m-thick transgressive succession. This unit filled a north-south-oriented valley system, developed in the underlying Jurassic volcanic complex.Lowstand fluvial deposits of the first stage of the valley-system fill occur in downdip segments of the system above a sequence boundary (SB). These fluvial deposits are overlain by coastal-plain and tide-dominated estuarine strata across an initial transgressive surface (ITS). In the northern sector the earliest valley infill is characterized by a transgressive fluvial succession, overlying a merged SB/ITS that is probably time-equivalent of marginal-marine deposits of the southern sector. The fluvial strata in the north are overlain by wave-dominated estuarine deposits. A drastic change to open-marine conditions is marked by a marine flooding surface, with local evidence of marine erosion (FS-RS). Open-marine strata are thin (<10 m) and dominated by lower-shoreface and offshore-transition deposits. They are capped by a younger flooding surface (FS), which represents the onset to offshore conditions across the study area due to a continuous long-term transgression that persisted until the Barremian.Although the interpreted depositional systems and stratigraphic architecture of the Springhill Formation resemble transgressive incised-valley-fill successions, the greater thickness and larger size of the Springhill valleys suggest inherited rift topography rather than valley development during a relative sea-level fall. 相似文献
4.
J.I. Massaferro P.I. Moreno G.H. Denton M. Vandergoes A. Dieffenbacher-Krall 《Quaternary Science Reviews》2009,28(5-6):517-525
We present chironomid and pollen records from the Huelmo site (～41°30′S), NW Patagonia, to examine in detail the timing and structure of climate changes during the Last Glacial Termination in the southern mid-latitudes. The chironomid record has the highest temporal and taxonomic resolution for this critical interval, and constitutes the first account of midge faunas at the culmination of the Last Glacial Maximum (LGM) for the region. The chironomid record suggests cold and wet conditions during the LGM, followed by deglacial warming between 17.6 and 16.8 cal kyr BP. Relatively warm conditions prevailed between ～15–14 cal kyr BP, followed by a reversal in trend with cooling pulses at ～14 and 13.5 cal kyr BP, and warming at the beginning of the Holocene. Cool-temperate conditions prevailed during the Huelmo Mascardi Cold Reversal (HMCR) which, according to chironomid data, exhibits a wet phase (13.5–12.8 cal kyr BP) followed by a conspicuous drier phase (12.8–11.5 cal kyr BP). The chironomid and pollen records from the Huelmo site indicate step-wise deglacial warming beginning at 17.6 cal kyr BP, in agreement with other paleoclimate records from NW Patagonia and isotopic signals from Antarctic ice cores. Peak warmth during the Last Glacial Termination was achieved by ～14.5 cal kyr BP, followed by a cooling trend that commenced during the Antarctic Cold Reversal, which later intensified and persisted during the HMCR (13.5–11.5 cal kyr BP). We observe a shift toward drier conditions at ～12.8 cal kyr BP superimposed upon the HMCR, coeval with intense fire activity and vegetation disturbance during Younger Dryas time. 相似文献
5.
Journal of Paleolimnology - We provide a photographic guide and taxonomic diagnosis of Chironomidae larval remains obtained from surface sediments and short cores of 92 waterbodies situated on the... 相似文献
6.
The original article to which this Erratum refers was published in Journal of Quaternary Science Vol 17 No 2 2002, pages 101–111 Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
7.
Fernanda Montes de Oca Luciana Motta María Sofía Plastani Cecilia Laprida Andrea Lami Julieta Massaferro 《Journal of Paleolimnology》2018,59(2):175-187
Remote lakes of northern Patagonia are ideal sites for examining climate- and non-climate-driven changes in aquatic ecosystems because there is little evidence of human influence and there is no detailed information on recent environmental trends in the region (i.e. the last 200 years). Subfossil chironomids (Diptera: Chironomidae) are useful paleoindicators due to their specific response to numerous environmental factors. Here, we analyze the chironomid subfossil assemblages from two remote lakes located in different environmental settings in Nahuel Huapi National Park of northern Patagonia, Argentina. Chironomids combined with sedimentary pigments (chlorophyll derivatives and total carotenoids) and organic matter provided information on the environmental history of the lakes for the last ca. 200 years. The 210Pb chronology and tephra layers are used to establish the chronology of changes in the chironomid assemblages associated to different environmental factors that impacted the area during the period covered by the study. The deposition of volcanic ash affected the abundance and composition of chironomid assemblage throughout the record of both lakes. However, changing climate conditions and human activities are also responsible for chironomid changes in the last 50 years. 相似文献
8.
Charqueño-Celis Fernanda Sigala Itzel Zolitschka Bernd Pérez Liseth Mayr Christoph Massaferro Julieta 《Journal of Paleolimnology》2022,67(2):115-129
Journal of Paleolimnology - There is little knowledge about testate amoebae in lakes and their responses to volcanic eruptions. To address this knowledge gap, we studied the paleoecology of these... 相似文献
9.
Piero Guilizzoni Aldo Marchetto Andrea Lami Frank Oldfield Marina Manca Claudio A. Belis Anna M. Nocentini Patrizia Comoli Vivienne J. Jones Steve Juggins Christina Chondrogianni Daniel Ariztegui John J. Lowe David. B. Ryves Richard W. Battarbee Tim C. Rolph Julieta Massaferro 《Journal of Paleolimnology》2000,23(2):117-127
We report the results of analyses of pigments (derived from algae and photosynthetic bacteria), diatoms and invertebrate fossil remains (ostracods, cladocerans, chironomids) in two late Pleistocene sediment cores from Lago Albano, a crater lake in Central Italy. The record contains evidence for oscillations in lake biota throughout the period ca. 28 to 17 k yr BP. The earliest of these are contained in the basal 3.5 m of light olive-gray and yellowish-gray spotted muds sampled in core PALB 94-1E from 70 m water depth. The later oscillations are best represented in the more extended sediment sequence recovered from a second core site, PALB 94-6B, in 30 m water depth. The sediments at site 1E, containing the earlier oscillations (ca. 28-24 k yr BP), predate any sedimentation at the shallower site, from which we infer an initially low lake level rising to permit sediment accumulation at site 6B from ca. 24 k yr onwards. At site 6B, massive silts rich in moss remains are interbedded with laminated silts and carbonates. These sediments span the period ca. 24 to 17 k yr and are interpreted as representing, respectively, times of shallow water alternating with higher lake stands, when the lake was stratified and bottom water was stagnant. A range of mutually independent chronological constraints on the frequency and duration of the oscillations recorded in the lake biota indicate that they were aperiodic and occurred on millennial to century timescales. We interpret them as responses to climate forcing through its impact on lake levels and changing aquatic productivity. The time span they occupy, their frequency and their duration suggest that at least some of these changes may parallel both the Dansgaard-Oeschger events recorded in Greenland Ice Cores and the contemporary oscillations in North Atlantic circulation documented in marine sediment cores. 相似文献
10.
