Paleodistribution of the alerce and cypres of the Guaitecas during the interstadial stages of the Llanquihue Glaciation: Llanquihue and Chiloé provinces, Los Lagos Region, Chile.
Paleodistribucion del alerce y cipres de las Guaitecas durante periodos interestadiales de la Glaciacion Llanquihue: provincias de Llanquihue y Chiloe, Region de Los Lagos, Chile.
| dc.contributor | en-US | |
| dc.contributor | es-ES | |
| dc.creator | Villagran, Carolina | |
| dc.creator | Leon, Ana | |
| dc.creator | Roig, Fidel A. | |
| dc.date | 2010-06-29 | |
| dc.identifier | http://www.andeangeology.cl/index.php/revista1/article/view/V31n1-a08 | |
| dc.identifier | 10.5027/andgeoV31n1-a08 | |
| dc.description | The purpose of this study is to contribute with new paleobotanical knowledge of the Seno de Reloncaví and the adjacent eastern and northern coast of Isla Grande de Chiloé. The authors have collected at eight different sites subfossil tree trunks of alerce (Fitzroya cupressoides (Mol.) Johnst.) and Guaitecas cypress (Pilgerodendron uviferum (D. Don) Florin). The tree trunks were in situ and very well preserved. According to six preliminary radiocarbon dates showing finite ages between 42.600 and 49.780 14C yr BP, the deposits with the tree trunks would correspond to interstadial stages of middle Llanquihue glaciation (isotopic stage 3). The authors have analyzed the stratigraphy and fossil pollen content at two of these sites, Isla Tenglo in the Llanquihue Province (41°30'S) and Punta Pirquén, along the eastern coast of Isla Grande de Chiloé (42°13'S). Conifer tree trunks at both sites are associated with organic silt and peat underlying a thick succession (2-4 m) of laminated grey silt (lacustrine rhytmite) and capped by fluvioglacial sand and gravel which correspond to the Last Glacial Maximum. The pollen spectra of the tree-containing organic deposits at the base of the succession are dominated mainly by arboreal forest taxa: Nothofagus dombeyi-type and several conifers, Fitzroya cupressoides (Mol.) Johnst., Pilgerodendron uviferum (D. Don) Florin, Saxe-gothaea conspicua Lindl., Podocarpus nubigena Lindl. and Lepidothamnus fonkii (Phil.) Ball. The spectra suggest a relatively warm and wet interstadial during middle Llanquihue glaciation. Conifer forests probably had wider and more continuous distribution than today, occupying lowland sites in the Central Depresion of Llanquihue and Chiloé provinces before the onset of the cold stadials of late Llanquihue glaciation (30.000-14.000 14C yr BC, isotopic stage 2). These forests have a disjunct distribution at present, with populations present on the summits and high elevation sites of both mountain ranges (Andes and Coastal) in the Lake Region, and small isolated populations present at lower elevations. This montane distribution is attributed to increasing temperatures since the late glacial and during the Holocene, and hence, the populations at lower elevations would be relicts from glacial stages, as it is suggested by a greater degree of genetic divergence present in these relicts as compared to the high elevation populations. | en-US |
| dc.description | Este estudio tiene como proposito dar a conocer recientes hallazgos paleobotanicos en el Seno de Reloncavi y costas oriental y norte de la isla Grande de Chiloe. Se trata de ocho sitios con troncos subfosiles de alerce (Fitzroya cupressoides (Mol.) Johnst.) y cipres de las Guaitecas (Pilgerodendron uviferum (D. Don) Florin), in situ y en muy buen estado de preservacion. De acuerdo a seis dataciones radiocarbonicas preliminares, con edades finitas entre 42.600 y 49.780 C14 anos AP, los depositos con los troncos corresponderian a lapsos interestadiales del periodo Llanquihue medio de la ultima glaciacion (estadio isotopico 3). Se analizo la estratigrafia y el contenido de polen fosil de dos de estos sitios, Isla Tenglo en la Provincia de Llanquihue (41°30'S) y Punta Pirquen, en la costa oriental de la isla Grande de Chiloe (42°13'S). En ambos sitios los troncos de coniferas se encuentran asociados a depositos de limo organico y turba, los cuales subyacen a potentes secuencias (2-4 m) de limo gris laminado (ritmitas lacustres), seguidos de la arena y grava glaciofluvial del ultimo Maximo Glacial. El espectro polinico, contenido en el deposito organico con troncos de la base de las secuencias, exhibe dominancia de polen arboreo, principalmente representado por Nothofagus tipo dombeyi y una serie de especies de coniferas, como Fitzroya cupressoides (Mol.) Johnst., Pilgerodendron uviferum (D. Don) Florin, Saxe-gothaea conspicua Lindl, Podocarpus nubigena Lindl. y Lepidothamnus fonkii (Phil.) Ball. El espectro sugiere que durante los interestadiales relativamente calidos y humedos del periodo medio de la glaciacion Llanquihue, los bosques con coniferas habrian tenido una distribucion mas amplia y continua que en la actualidad, poblando los sitios bajos de la Depresion Intermedia de las provincias de Llanquihue y Chiloe, antes de los lapsos estadiales frios del periodo Llanquihue tardio (30.000-14.000 14C anos AP, estadio isotopico 2). Actualmente, los bosques de coniferas exhiben distribucion disyunta, en las cimas y en sitios de mayor altitud de ambas cordilleras de la Region de Los Lagos, y pequenas poblaciones aun persisten en los sitios bajos. La distribucion montanosa moderna es atribuida al ascenso de las temperaturas durante el Tardiglacial y Holoceno y, asi, las poblaciones de sitios bajos serian relictos de epocas glaciales, como lo sugiere su mayor grado de divergencia genetica, en comparacion con las poblaciones de altura. | es-ES |
| dc.format | application/pdf | |
| dc.format | text/html | |
| dc.language | eng | |
| dc.publisher | Servicio Nacional de Geología y Minería | en-US |
| dc.relation | http://www.andeangeology.cl/index.php/revista1/article/view/V31n1-a08/599 | |
| dc.relation | http://www.andeangeology.cl/index.php/revista1/article/view/V31n1-a08/html | |
| dc.source | Andean Geology; Vol 31, No 1 (2004); 133-151 | es-ES |
| dc.source | Andean Geology; Vol 31, No 1 (2004); 133-151 | en-US |
| dc.source | 0718-7106 | |
| dc.source | 0718-7092 | |
| dc.title | Paleodistribution of the alerce and cypres of the Guaitecas during the interstadial stages of the Llanquihue Glaciation: Llanquihue and Chiloé provinces, Los Lagos Region, Chile. | en-US |
| dc.title | Paleodistribucion del alerce y cipres de las Guaitecas durante periodos interestadiales de la Glaciacion Llanquihue: provincias de Llanquihue y Chiloe, Region de Los Lagos, Chile. | es-ES |
| dc.type | info:eu-repo/semantics/article | |
| dc.type | info:eu-repo/semantics/publishedVersion | |
| dc.type | es-ES | |
| dc.type | en-US |
This item appears in the following Collection(s)
-
Andean Geology
[0-9]{4}