Early to Mid-Holocene Aridity in Central Chile and the Southern Westerlies: The Laguna Aculeo Record (34°S)

Abstract

Central Chile (32–35°S) lies at the northern border of strong Westerly influence and thus exhibits a steep precipitation gradient. Therefore, the palaeoclimatic archives in the region are suitable for detecting past moisture changes. The study of Laguna Aculeo (33°50'S, 70°54'W) presents a multiproxy Holocene lake record including sedimentology, geochemistry, mineralogy, pollen, diatoms, and radiocarbon dating (17 dates). Results indicate an arid early to mid-Holocene period (about 9500–5700 cal yr B.P.). After 5700 cal yr B.P. effective moisture increased progressively and around 3200 cal yr B.P., modern humid conditions were established. Numerous intercalated clastic layers reflect flood deposition during rainy winters. A fluvial unit was deposited shortly before 9000 cal yr B.P. Subsequently, flood events were absent until 5700 but have become frequent since 3200 cal yr B.P. The frequency of flood layers possibly points to weak or no El Niño activity during the early and mid-Holocene, with a subsequent increase during the late Holocene. During the early and mid-Holocene, the Westerlies were probably blocked and hence deflected southward by the subtropical high-pressure cell. Higher precipitation during the last 3200 yr seems strongly related to a weakened subtropical high-pressure cell with intensified Westerlies and possibly increased El Niño activity.

Glacial to Holocene Paleoceanographic and Continental Paleoclimate Reconstructions Based on ODP Site 1233/GeoB 3313 Off Southern Chile

“…6.9). These data show generally drier conditions during the early and middle Holocene and increased precipitation during the late Holocene consistent with regional terrestrial records from Chiloé Island (e.g., Abarzúa et al 2004) and central Chile (e.g., Jenny et al 2002;Villagrán and Varela 1990), as well as marine records located further north (Lamy et al 1999). Similarly, marine productivity (based on organic carbon and opal contents) along the southern part of the PCC was lower during the early and middle Holocene (Fig.…”

A 70,000 year multiproxy record of climatic and environmental change from Rano Aroi peatland (Easter Island)

“…The timing of this transition lags that of eastern circumpacific regions, where it occurred approx. 4 cal kyr BP, as shown by many Altiplano lacustrine (Jenny et al, 2002;Paduano et al, 2003;Valero-Garcés et al, 2005) and marine records (Lamy et al, 2001).…”

Ocupaciones Humanas Del Holoceno Medio en Los Andes Del Norte Semiárido De Chile (31° S, Combarbalá): Función Del Sitio E Implicancias Para El Uso Regional Del Espacio

“…Aunque las resoluciones varían, varios registros terrestres y marinos indican condiciones áridas entre 9000 y 5500 cal a.p. (Jenny et al 2002;Kim et al 2002;Maldonado y Villagrán 2006;Valero-Garcés et al 2005;Veit 1996; entre otros). Esta fase seca se interpreta como resultado de la migración del cinturón de vientos del Oeste hacia latitudes más altas.…”

“…Los datos regionales indican un aumento gradual de la humedad a partir de 5700 cal a.p., con un incremento significativo entre 4200 y 3800 cal a.p. (Maldonado y Villagrán 2002, 2006, en coincidencia con otros registros (Jenny et al 2002), que apoyan el establecimiento de los patrones climáticos actuales entre 4500 y 4000 cal a.p. (Rein et al 2005 …”

“…), coinciden plenamente con los pulsos de mayor aridez en el NSA y áreas vecinas (Grasset 2014;Jenny et al 2002;Maldonado y Villagrán 2006), la erosión de suelos (Veit 1996), el alza de las temperaturas de la superficie marina (Kim et al 2010) y, a una escala más amplia, disminución de la actividad de ENSO (Rein et al 2005). A una escala macrorregional se ha postulado que en los ambientes cordilleranos efectivamente dicho pulso seco no significó una merma en la señal arqueológica (Méndez et al 2015), como sí en otras áreas (Neme y Gil 2009).…”