Www Winds South Chile Holocene

Viewed from this very general, low-resolution perspective, full glacial-early Holocene lake records along the PEP 1 transect (Fig. 22) document only six major interacting climate scenarios (Fig. 23):

1. Unglaciated Arctic lake systems witness progressive warming related to deglaciation by a reduction in the thickness and seasonal extent of ice cover and a concomitant increase in productivity. Additional records could certainly show other climate/lake interactions related to changing moisture sources and winds, changing seasonality of insolation, and varying styles of land/lake interactions mediated by vegetation and erosion changes under climate control.

2. Midlatitude, western North American late glacial lakes responded to an intensification and greater persistence of westerly moisture delivered by storm tracks forced south by climate changes that encouraged the growth of ice sheets and southerly displacement of polar air masses.

3. South of central México and north of Lago Titicaca in southern Bolivia (16.0°S), all lacustrine systems seem to have been low or dry in the full glacial period, apparently as a consequence of substantially reduced ITCZ / trade wind circulation systems that today provide moisture to these basins. Late glacial moisture increases characterized the western sites, whereas the timing of the arrival of easterly moisture approximately coincided with the beginning of the Holocene at the eastern lake sites (Lago de Valencia and Laguna Los Lirios). The spatial coherence and climatic significance of this apparent gradient must await additional study of well-dated records.

4. Lake records from southern South America at lat itudes 16°-23.5°S were also low or dry during the full glacial period, but record important high stands during the late glacial period. The most notable of these (the

Tauca lake stage) occurred at Lago Titicaca and Salar de

Uyuni, but apparently not at Laguna Lejía (23.5°S), which rose to higher than modern levels only during the latest glacial and early Holocene. Barring unfore seen chronological problems at these sites, the reasons for this rise are not understood at present. They may re late to cool ocean temperatures coupled with the location of the northern, moisture-bearing limbs of high-pressure systems generated by polar outbreaks or other mechanisms. The oceans may have been too cold and

Www Winds South Chile Holocene

FIGURE 23 Summary of hypothesized climate causes of full to late glacial lake status changes compared to the Holocene along the Pole-Equator-Pole: Americas (PEP 1) transect. The numbers that identify roughly coherent paleoclimatic scenarios correspond to the numbered conclusions in Section 16.4. ka = thousands of radiocarbon years before present. Locations of sites are given in Fig. 1.

FIGURE 23 Summary of hypothesized climate causes of full to late glacial lake status changes compared to the Holocene along the Pole-Equator-Pole: Americas (PEP 1) transect. The numbers that identify roughly coherent paleoclimatic scenarios correspond to the numbered conclusions in Section 16.4. ka = thousands of radiocarbon years before present. Locations of sites are given in Fig. 1.

(or) the appropriate wind systems too far equatorward to provide moisture to Laguna Lejía until the early Holocene.

5. Between 30° and 41°S latitude, two lake systems, Salinas del Bebedero and Laguna Cari Laufquen, document high lake stages during the full and early late glacial periods and lower levels thereafter. These changes may also reflect moisture sources related to outbreaks of polar air and the interaction with low-pressure systems in the western Atlantic. Such pro cesses would have been most active and intense in the winter, and precipitation derived from them could have maintained lakes in otherwise arid environments. Cooler overall temperatures clearly contributed to a positive moisture balance. Low temperatures may have been more important than precipitation per se in reducing evaporation and allowing high lake stages.

6. South of latitude 45°S, Lago Cardiel is the only studied representative of lake systems with sediment and geomorphic evidence of past lake stages higher than modern levels. Lago Cardiel has no record of full or late glacial stages higher than its present, comparatively low levels. If it was indeed low during the full and late glacial periods, the reason may be ascribed to a cold South Pacific Ocean and a northward displacement of westerly storm tracks beyond the latitude of Lago Cardiel. If so, higher than modern levels in the early Holocene period must reflect warm ocean sources of moisture finally reaching relevant latitudes to the south and the poleward retreat of the westerlies to deliver the moisture to the lake as happens today.

At this scale of resolution, it appears that past inter-hemispheric climate interactions in the Western Hemisphere are synchronous, but not necessarily of the same sign, and are therefore linked, at least indirectly. The massive Laurentide/Cordilleran ice sheet or those processes that sustained it may have forced climate changes throughout the western Northern Hemisphere and perhaps even as far south as central South America. The southerly displacement of westerly storm tracks in North America has been modeled (Kutzbach, 1987), and western North America lake records register this displacement. Easterly precipitation sources associated with the ITCZ diminished in importance or disappeared altogether, perhaps as a consequence of general cooling in tropical and subtropical regions. At least no records in northern and central South America studied so far appear to document increased easterly (ITCZ) precipitation during full or early late glacial times. To account for dry conditions during the full and late glacial periods, the ITCZ is supposed to have resided farther north by South American workers (e.g., Martin et al., 1997) and farther south by North American workers (e.g., Bradbury, 1997). Perhaps the resolution to this problem lies in the weakening, restriction, and redirection of easterly moisture sources by the effects of mobile polar highs as has been suggested by Leroux (1993).

A late glacial expansion of southern South American lakes as a result of intensified and more northerly displaced westerly moisture sources conflicts with pollen evidence at the same latitude west of the Andes. As a consequence, precipitation of moisture from the southwest Atlantic, related to outbreaks of polar air originating over a very cold Antarctica, may have provided a positive hydrologic balance for these lacustrine systems. The synchroneity of midlatitude lake-level records in both hemispheres probably relates to much colder polar climates ultimately thought to be caused by reduced heat transport to the north and south related to reduced thermohaline circulation controlled by glacial meltwater processes in the North Atlantic Ocean (e.g., Alley, 1995).

To provide relevant input to interhemispheric pale-oclimate interactions and histories, future paleolimno-logical studies must concentrate on high-resolution, multiproxy analyses, including coherent, fine-scale sediment facies analyses with chronological control at millennial scales. Most important, paleolimnological records must be convincingly related to local and regional climate controls through both neolimnological and climate monitoring.

References

Abbott, M. B., M. W. Binford, M. Brenner, and K. R. Kelts, 1997: A3500 14C yr high-resolution record of water-level changes in Lake Titicaca, Bolivia/Peru. Quaternary Research, 47: 70-80. Ager, T. A., 1982: Vegetational history of western Alaska during the Wisconsin glacial interval and the Holocene. In Hopkins, D. M., J. V. Mathews, Jr., C. E. Schweger, and S. B. Young (eds.), Paleoe-cology of Beringia. New York: Academic Press, pp. 75-93. Ager, T. A., and L. Brubaker, 1985: Quaternary palynology and vegetational history of Alaska. In Bryant, V., Jr., and R. Holloway (eds.), Pollen Records of Late Quaternary North American Sediments. Dallas, TX: American Association of Stratigraphic Palynologists Foundation, pp. 353-384. Allen, B. D., and R. Y. Anderson, 1993: Evidence from western North America for rapid shifts in climate during the last glacial maximum. Science, 260: 1920-1923. Alley, R. B., 1995: Resolved, the Arctic controls global climate change. In Smith, W. O., and J. M. Grebmeier (eds.), Arctic oceanography: Marginal ice zones and continental shelves. Coastal and Estuarine Studies, 49: 263-283. Ariztegui, D., M. M. Bianchi, J. Masafero, E. Lafargue, and F. Niessen, 1997: Interhemispheric synchrony of late glacial climatic instability as recorded in proglacial Lake Mascardi, Argentina. Journal of Quaternary Sciences, 12(4): 333-338. Bachhuber, F. W., 1982: Quaternary history of the Estancia Valley, central New Mexico. New Mexico Geological Society Guidebook, 33rd Field Conference, pp. 343-346. Bahls, L. C., E. E. Weber, and J. O. Jarvie, 1984: Ecology and distribution of major diatom ecotypes in the southern Fort Union Coal Region of Montana. U.S. Geological Survey Professional Paper 1289, 151 pp.

Barnosky, C. W., P. M. Anderson, and P. J. Bartlein, 1987: The northwestern U.S. during deglaciation: Vegetational history and pa-leoclimatic implications. In Ruddiman, W. F., and H. E. Wright, Jr. (eds.), North America and the Adjacent Oceans During the Last Deglaciation, Vol. K-3, The Geology of North America. Boulder, CO: Geological Society of America, pp. 289-321. Benson, L. V., D. R. Currey, R. I. Dorn, K. R. Lajoie, C. G. Oviatt, S. W. Robinson, G. I. Smith, and S. Stine, 1990: Chronology of expansion and contraction of four Great Basin lake systems during the past 35,000 years. Palaeogeography, Palaeoclimatology, Palaeoecology, 78: 241-276.

Benson, L., D. Currey, Y. Lao, and S. Hostetler, 1992: Lake-size variations in the Lahontan and Bonneville basins between 13,000 and 9000 14C years B.P. Palaeogeography, Palaeoclimatology, Palaeoecolo-gy, 95: 19-32.

Bradbury, J. P., 1991: Late Cenozoic diatom stratigraphy and paleo-limnology of Tule Lake, Siskiyou Co. California. Journal of Paleo-limnology, 6: 205-255. Bradbury, J. P., 1997: Sources of glacial moisture in Mesoamerica.

Quaternary International, 43/44: 97-110.

Bradbury, J. P., in press: Limnologic history of Lago de Pátzcuaro, Mi-choacán, México for the past 48,000 years; impacts of climate and man. Palaeogeography, Palaeoclimatology, and Palaeoecology.

Bradbury, J. P., and R. M. Forester, in press: Environment and pale-olimnology of Owens Lake, California: A record of climate and hydrology for the past 50,000 years. Washington, DC: Smithsonian Institution.

Bradbury, J. P., B. W. Leyden, M. Salgado-Labouriau, W. M. Lewis, Jr., C. Schubert, M. W. Binford, D. G. Frey, D. R. Whitehead, and F. H. Weibezahn, 1981: Late Quaternary environmental history of Lake Valencia, Venezuela. Science, 214: 1299-1305.

Bush, M. B., D. R. Piperno, P. A. Colinvaux, P. E. de Oliveira, L. A. Krissek, M. C. Miller, and W. E. Rowe, 1992: A14C 300-year pale-oecological profile of a lowland tropical lake in Panama. Ecological Monographs, 62: 251-275.

Colinvaux, P. A., M. B. Bush, M. Steinitz-Kannan, and M. C. Miller, 1997: Glacial and postglacial pollen records from the Ecuadorian Andes and Amazon. Quaternary Research, 48: 69-78.

Cumming, B. F., S. E. Wilson, R. J. Hall, and J. P. Smoll, 1995: Diatoms from British Columbia (Canada) lakes and their relationship to salinity, nutrients, and other limnological variables. Bibliotheca Di-atomologica, 31: 207.

D'Antoni, H. L., 1983: Pollen analysis of Gruta del Indio. Quaternary of South America and Antarctic Peninsula, 1: 83-104.

Déletang, L. F., 1929: Contribución al estudio de las salinas Argentinas. La Salina del Bebedero y sus relaciones con el sistema hidrográfico Andino o de Desaguadero: Ministerio de Agricultura de la Nación, Division General de Minas, Geología e Hidrología, Publicación 47, pp. 1-69.

Fox, A. N., and M. R. Strecker, 1991: Pleistocene and modern snowlines in the central Andes (24-28°S). Bamberger Geographische Schriften, 11: 169-182.

Galloway, R. W., V. Markgraf, and J. P. Bradbury, 1988: Dating shorelines of lakes in Patagonia, Argentina. Journal of South American Earth Sciences, 1: 195-198.

Geyh, M. A., M. Grosjean, L. Nuñez, and U. Schotterer, 1999: Radiocarbon reservoir effect and the timing of the late-glacial/early Holocene humid phase in the Atacama Desert, northern Chile. Quaternary Research, 52: 143-153.

González, M. A., 1994: Salinas del Bebedero Basin (República Argentina). In Kelts, K., and E. Gierlowski-Cordesch (eds.), Global Inventory of Lake Basins. Cambridge, U.K.: Cambridge University Press, pp. 381-386.

González, M. A., and N. I. Maidana, 1998: Post Wisconsin paleoenvi-ronments at Salinas del Bebedero basin (33°20' S, 66°45' W, 380 m asl; San Luis, Argentina). Journal of Paleolimnology, 20: 353-368.

Grosjean, M., and A. L. Nuñez, 1994: Late glacial, early and middle Holocene environments, human occupation and resource use in the Atacama (Northern Chile). Geoarchaeology, 9: 271-286.

Grosjean, M., M. A. Geyh, B. Messerli, and U. Schotterer, 1995: Late glacial and early Holocene lake sediments, ground-water formation and climate in the Atacama Altiplano 22-24°S. Journal of Paleolimnology, 14: 241-252.

Hansen, B. C. S., H. E. Wright, and J. P. Bradbury, 1984: Pollen studies in the Junín area, central Peruvian Andes. Geological Society of America Bulletin, 95: 1454-1465.

Helmens, K. F., P. Kuhry, N. W. Rutter, K. Van Der Borg, and A. F. De Jong, 1996: Warming at 18,000 yr B.P. in the tropical Andes. Quaternary Research, 45: 289-299.

Kutzbach, J. E., 1987: Model simulations of the climatic patterns during the deglaciation of North America. In Ruddiman, W. F., and H. E. Wright (eds.), North America and Adjacent Oceans During the Last Deglaciation, Vol. K-3, The Geology of North America. Boulder, CO: Geological Society of America, pp. 425-446.

Lee, W. T., 1906: Geology and water resources of Owens Valley, Cali fornia. U.S. Geological Survey Water Supply and Irrigation Paper 181, 28 pp.

Leroux, M., 1993: The mobile polar high: A new concept explaining present mechanisms of meridional air-mass and energy exchanges and global propagation of paleoclimatic changes. Global Planetary Change, 7: 69-93.

Leyden, B. W., 1985: Late Quaternary aridity and Holocene moisture fluctuations in the Lake Valencia basin, Venezuela. Ecology, 66(4): 1279-1295.

Leyden, B. W., M. Brenner, D. A. Hodell, and J. H. Curtis, 1993: Late Pleistocene climate in the Central American lowlands. In Swart, P. K., K. C. Lohmann, J. McKenzie, and S. Savin (eds.), Climate Change in Continental Isotopic Records, Washington, DC: American Geophysical Union, Geophysical Monograph 78, pp. 165-178.

Lowell, T. V., C. J. Heusser, B. G. Andersen, P. I. Moreno, A. Hausser, L. E. Heusser, D. R. Schlüchter, D. R. Marchant, and G. H. Denton, 1995: Interhemispheric correlation of late Pleistocene glacial events. Science, 269: 1541-1549.

Marengo, J. A., and J. C. Rogers, 2000: Polar air outbreaks in the Americas: Assessments and impacts during modern and past climates. In Markgraf, V. (ed.), Interhemispheric Climate Linkages. San Diego: Academic Press, Chapter 3.

Markgraf, V., and M. M. Bianchi, 1999: Paleoenvironmental changes during the last 17,000 years in western Patagonia: Mallín Aguado, Province of Neuquen, Argentina. Bamberger Geographische Schriften, 19:175-193.

Markgraf, V., Baumgartner, T. R., Bradbury, J. P., Diaz, H. F., Dunbar, R. B., Luckman, B. H., Seltzer, G. O., Swetnam, T. W., Villalba, R., 2000: Paleoclimate reconstruction along the Pole-Equator-Pole transect of the Americas (PEP 1). Quaternary Science Reviews, 19: 125-140.

Markgraf, V., J. R. Dodson, A. P. Kershaw, M. S. McGlone, and N. Nichols, 1992: Evolution of late Pleistocene and Holocene climates in the circum-South Pacific lake areas. Climate Dynamics, 6: 193-211.

Martin, L., J. Bertaux, T. Correge, M.-P. Ledru, P. Mourguiart, A. Sifed-dine, F. Soubies, D. Wirrmann, K. Suguio, and B. Turc, 1997: Astronomical forcing of contrasting rainfall changes in tropical South America between 12,400 and 8800 cal yr B.P. Quaternary Research, 47: 117-122.

Messerli, B., M. Grosjean, K. Graf, U. Schotterer, H. Schreier, and M. Vuille, 1992: Die Veränderungen von Klima und Umwelt in der Region Atacama (Nordchile) Seit der letzten Kaltzeit. Erdkunde, 46: 257-272.

Metcalfe, S. E., A. Bimpson, A. J. Courtice, S. L. O'Hara, and D. M. Taylor, 1997: Climate change at the monsoon? Westerly boundary in northern México. Journal of Paleolimnology, 17: 155-171.

Moreno, P. I., 1997: Vegetation and climate near Lago Llanquihue in the Chilean Lake District between 20 200 and 9500 14C yr BP. Journal of Quaternary Science, 12: 485-500.

Rind, D., 1998: Latitudinal temperature gradients and climate change. Journal of Geophysical Research, 103: 5943-5971.

Servant, M., and J. C. Fontes, 1978: Les lacs quaternaires des hauts plateaux des Andes Boliviennes. Premières interprétations paléoclimatiques. Cahiers ORSTOM, Série Géologie, 10(1): 9-23.

Servant, M., M. Fournier, J. Argollo, S. Servant-Vildary, F. Sylvestre, D. Wirrmann, and J.-P. Ybert, 1995: La denière transition glaciaire / interglaciaire des Andes tropicales sud (Bolivie) d'après l' étude des variations des niveaux lacustres et des fluctuations glaciaires. Comptes Rendus Académie des Sciences de Paris, ser. II a, 320: 729 -736.

Servant-Vildary, S., 1992: The diatoms. In Dejoux, C., and A. Iltis (eds.), Lake Titicaca: A Synthesis of Limnological Knowledge. Dordrecht: Kluwer Academic, pp. 163-176.

Servant-Vildary, S., and M. Roux, 1990: Multivariate analysis of di-

atoms and water chemistry in Bolivian saline lakes. Hydrobiologia, 197: 267-290.

Stine, S., and M. Stine, 1990: A record from Lake Cardiel of climate change in southern South America. Nature, 345: 705-707.

Sylvestre, F., 1997: Le denier transition glaciaire-interglaciaire (18000-8 000 14C ans B.P.) des Andes tropicales sud Bolivie) d'après l'étude des diatomées: These doctoral Museum National d'Histoire Naturelle (Paris), 243 pp.

Sylvestre, F., S. Servant-Vildary, M. Fournier, and M. Servant, 1996: Lake-levels in the southern Bolivian Altiplano (19°-21°S) during the late glacial based on diatom studies. International Journal of Salt Lake Research, 4: 281-300.

Sylvestre, F., M. Servant, S. Servant-Vildary, C. Causse, and M. Fournier, 1999: Lake-level chronology in the south Bolivian Altiplano (18°-23°S) during late-glacial time and the early Holocene. Quaternary Research, 51: 54-66.

Thompson, R. S., C. Whitlock, P. J. Bartlein, S. P. Harrison, and W. G. Spaulding, 1993: Climatic changes in the western United States since 18,000 yr B. P. In Wright, H. E., Jr., J. E. Kutzbach, T. Webb, III, W. F. Ruddiman, F. A. Street-Perrot, and P. J. Bartlein (eds.), Global Climates Since the Last Glacial Maximum. Minneapolis: University of Minnesota Press, pp. 468-513.

Van Devender, T. R., 1990: Late Quaternary vegetation and climate of the Chihuahuan Desert, United States and México. In Betancourt, J. L., T. L. Van Devender, and P. S. Martin (eds.), Packrat Middens. Tucson: University of Arizona Press, pp. 104-133.

Van Geel, B., and T. Van der Hammen, 1973: Upper Quaternary veg-etational and climatic sequence of the Fúquene area (eastern cordillera, Colombia). Palaeogeography, Palaeoclimatology, Palaeo-ecology, 14: 9-92.

Vázquez-Selem, L., 1998: Glacial chronology of Iztaccíhuatl volcano, Central México, based on cosmogenic 36Cl exposure ages and tephrochronology [abs.]. American Quaternary Association Program and Abstracts of the 15th Biennial Meeting, Puerto Vallarta, México, p. 174.

Villagran, C., and Varela, J., 1990: Palynological evidence for increased aridity on the central Chilean coast during the Holocene. Quaternary Research, 34: 198-207.

Watts, W. A., and J. P. Bradbury, 1982: Paleoecological studies at Lake Pátzcuaro on the west-central Mexican Plateau and at Chalco in the Basin of México. Quaternary Research, 17: 56 -70.

Weingarten, B., 1988: Geochemical and clay-mineral characteristics of lake sediments from the Venezuelan Andes: Modern climatic relations and paleoclimatic interpretation. Ph.D. thesis. University of Massachusetts, Amherst, 213 pp.

Wirrmann, D., 1987: El Lago Titicaca: Sedimentología y paleo-hidrología durante el Holoceno (10 000 años B.P. actual). Informe, UMSA, ORSTOM, La Paz, 6, 61 pp.

Wirrmann, D., P. Mourguiart, and L. F. de Oliveira Almeida, 1988: Holocene sedimentology and ostracodes repartition in Lake Titicaca. Paleohydrological interpretations. In Rabassa, J. (ed.), Quaternary of South America and Antarctic Peninsula, 6: 89-127.

Ybert, J. P., 1992: Ancient lake environments as deduced from pollen analysis. In Dejoux, C., and A. Iltis (eds.), Lake Titicaca: A Synthesis of Limnological Knowledge. Dordrecht: Kluwer Academic, pp. 49-62.

This Page Intentionally Left Blank

Vegetation Evidence

This Page Intentionally Left Blank

Was this article helpful?

0 0

Post a comment