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A Late Glacial–Holocene Tephrochronology for Glacial Lakes in Southern Ecuador

  • Donald T. Rodbell (a1), Stefan Bagnato (a1), Jeffrey C. Nebolini (a1), Geoffrey O. Seltzer (a2) and Mark B. Abbott (a3)...


Despite the presence of numerous active volcanoes in the northern half of Ecuador, few, if any, distal tephras have been previously recognized in the southern one third of the country. In this article, we document the presence of thin (0.1–1.0-cm-thick) distal tephras comprising glass and/or phenocrysts of hornblende and feldspar in sediment cores from five glacial lakes and one bog in Las Cajas National Park (2°40′–3°00′S, 79°00′–79°25′W). The lake cores contain from 5 to 7 tephras, and each has a diagnostic major element geochemistry as determined from electron microprobe analysis of ∼710 glass shards and ∼440 phenocrysts of feldspar and hornblende. The loss of sodium with exposure to the electron microbeam causes a 10±7 wt.% (±1σ) reduction in Na content, which we empirically determined and corrected for before correlating tephras among the sediment cores. We use a similarity coefficient to correlate among the sediment cores; pair-wise comparison of all tephras generally yields an unambiguous correlation among the cores. Six tephras can be traced among all or most of the cores, and several tephras are present in only one or two of the cores. Twenty-six accelerator mass spectrometry 14C dates on macrofossils preserved in the sediment cores provide the basis for establishing a regional tephrochronology. The widespread tephras were deposited ∼9900, 8800, 7300, 5300, 2500, and 2200 cal yr B.P. The oldest tephras were deposited ∼15,500 and 15,100 cal yr B.P., but these are not found in all cores. Two of the tephras appear correlative with volcaniclastic strata on the flanks of Volcán Cotopaxi and one tephra may correlate with strata on the flanks of Volcán Ninahuilca; both volcanoes are in central Ecuador. The absence of tephras in sediment cores correlative with the numerous eruptions of active volcanoes of the past two millennia implies that the earlier eruptions, which did deposit tephras in the lakes, must have been either especially voluminous, or southerly winds must have prevailed at the time of the eruption, or both.



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Bagnato, S Tephrochronology of late Quaternary sediment cores from southern Ecuador. (2000). Union College, Schenectady.
Barazangi, M, and Isacks, B.L Spatial distribution of earthquakes and subduction of the Nazca plate beneath South America. Geology 4, (1976). 686692.
Borchardt, G.A, Aruscavage, P.J, Millard, H.T Jr. Correlation of the Bishop ash, a Pleistocene marker bed, using instrumental neutron activation analysis. Journal of Sedimentary Petrology 42, (1972). 301306.
Clapperton, C.M, and Vera, R The Quaternary glacial sequence in Ecuador: A reinterpretation of the work of Walter Sauer. Journal of Quaternary Science 1, (1986). 4556.
Colinvaux, P.A, Bush, M.B, Steinitz-Kannan, M, and Miller, M.C Glacial and postglacial pollen records from the Ecuadorian Andes and Amazon. Quaternary Research 48, (1997). 6978.
Delano, J.W, Tice, S.J, Mitchell, C.E, and Goldman, D Rhyolitic glass in Ordovician K-bentonites: A new stratigraphic tool. Geology 22, (1994). 115118.
Direccı́on General de Geologı́a y Minas. (1975). Mapa Geologico del Ecuador, Hoja 53 (Cuenca) 1:100,000: Quito.
Francis, P. (1993). Volcanoes: A Planetary Perspective, Oxford University Press, Oxford.
Froggatt, P.C Standardization of the chemical analysis of tephra deposits. Report of the ICCT Working Group. Quaternary International 13, (1992). 9396.
Goodman, A.Y Glacial Geology and Soil Catena Development on Moraines in Las Cajas National Park, Ecuador. (1996). Union College, Schenectady.
Hall, M. L., and Beate, B. (1991). El volcanismo plio-cuaternario en los Andes del Ecuador.. In El Paisaje Volcanico de la Sierra Ecuatoriana Mothes, P. A., Ed., pp. 517. Corporacion Editora Nacional, Quito. [In Spanish]
Hall, M.L, and Mothes, P.A Tefroestratigrafı́a holocénica de los volcanes principales del valle interandino, Ecuador. Marocco, R El Contexto Geológico del Espacio Fı́sico Ecuatoriano. (1994). Corporación Editora Nacional, Quito. 4767.
Hall, M.L, and Wood, C.A Volcano-tectonic segmentation of the northern Andes. Geology 13, (1985). 203207.
Hallett, D.J, Mathewes, R.W, Foit, F.F Jr. Mid-Holocene glacier peak and Mount St. Helens We tephra layers detected in lake sediments from Southern British Columbia using high resolution techniques. Quaternary Research 55, (2001). 284292.
Hunt, J.B, and Hill, P.G Tephra geochemistry: A discussion of some persistent analytical problems. The Holocene 3, (1993). 271278.
Mothes, P.A Lahars of Cotopaxi Volcano, Ecuador: Hazard and risk evaluation. McCall, G.J.H, Laming, D.J.C, and Scott, S.C Geohazards Natural and Man-made. (1992). Chapman and Hall, London. 5363.
Mothes, P.A, and Hall, M.L El paisaje interandino y su formación por eventos volcánicos de gran magnitud. Mothes, P.A El Paisaje Volcanico de la Sierra Ecuatoriana. (1991). Corporacion Editora Nacional, Quito. 1938.
Nebolini, J.C Geochemical Fingerprinting of Tephra Layers Preserved in Lake Cores in Las Cajas National Park, Ecuador. (1996). Union College, Schenectady.
Nielsen, C.H, and Sigurdsson, H Quantitative methods for electron microprobe analysis of sodium in natural and synthetic glasses. American Mineralogist 66, (1981). 547552.
Rodbell, D.T, Seltzer, G.O, Abbott, M.B, Hansen, B.C.S, Goodman, A.Y, and Nebolini, J.C Tephrochronology, sedimentology, and palynology of late glacial-Holocene lake sediment cores from southern Ecuador. EOS Transaction 77, (1996). F30
Rodbell, D.T, Seltzer, G.O, Anderson, D.M, Abbott, M.B, Enfield, D.B, and Newman, J.H A ∼15,000 year record of El-Niño driven alluviation in southwestern Ecuador. Science 283, (1999). 516520.
Sillitoe, R.H Tectonic segmentation of the Andes: Implications for magmatism and metallogeny. Nature 250, (1974). 542545.
Stuiver, M, Reimer, P.J, Bard, E, Beck, J.W, Burr, G.S, Hughen, K.A, Kromer, B, McCormac, F.G, van der Plicht, J, and Spurk, M INTCAL 98 radiocarbon age calibration, 24,000–0 cal B.P. Radiocarbon 40, (1998). 10411083.
Wright, H.E Coring tips. Journal of Paleolimnology 6, (1991). 3749.


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A Late Glacial–Holocene Tephrochronology for Glacial Lakes in Southern Ecuador

  • Donald T. Rodbell (a1), Stefan Bagnato (a1), Jeffrey C. Nebolini (a1), Geoffrey O. Seltzer (a2) and Mark B. Abbott (a3)...


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