Sedimentology and stable isotopes from a lacustrine-to-palustrine limestone deposited in an arid setting, climatic and tectonic factors: Miocene–Pliocene Opache Formation, Atacama Desert, Chile

Wet, Carol B. de; Godfrey, Linda; Wet, Andrew P. de

doi:10.1016/j.palaeo.2015.02.039

Cited by 23 publications

(17 citation statements)

References 94 publications

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“…Salt accumulation resumed, but at much higher rates, especially during the deposition of the uppermost 200 m [21,23]. These accumulation changes are roughly consistent with the paleoclimate history of the area, with semi-arid to arid conditions occurring in the late Miocene-Pliocene before switching to being hyper arid [24][25][26][27] when salt deposition was most rapid. Coincident changes in relief, climate and salt accumulation suggest they may be linked to drainage, either in terms of drainage basin size, water fluxes and/or solute fluxes if the solute concentration has changed through time.…”

Section: Background To the Salar De Atacamasupporting

confidence: 72%

Volcanic and Saline Lithium Inputs to the Salar de Atacama

Godfrey

Álvarez-Amado

2020

Minerals

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The Li-rich brine contained within the halite body of the Salar de Atacama is uncommon for two reasons: First, it has an exceptionally high Li concentration, even compared to other closed basins in the Li triangle of South America; and second, it is widespread within the halite nucleus and not restricted to a localized area. This study focusses on the southern half of the salar where Li production occurs and draws comparisons with its northern neighboring basin through which the Loa river flows. Concentration and isotope data for water inflowing to this part of the salar were obtained from surface inflow as well as wells located within the alluvial fans on its eastern margin. Lithium varies between 0.2 and 20 mg/L before reaching the salar where small amounts of the brine and or salts that precipitated from it can increase its concentration up to 400 mg/L or higher. The δ7Li of the inflow water varies between +4.9‰ and +11.2‰ and increases to +12.6‰ within the salar margin, consistent with salar brine based on reported measurements. Boron isotopes indicate that it is unlikely that solutes are derived from sedimentary evaporites or mineral cements, unlike the situation in the adjacent Loa basin. Water that flows through an aquifer laterally confined by a basement block and a line of volcanoes has a notably higher δ7Li than other inflow water, around +9‰, and increasing to +10.5‰. δ7Li values are overall higher than were measured in the adjacent Loa basin, indicating that here the water–rock reactions for Li are more evolved due to longer residence times. Lithium concentrations increased with sodium and chloride, but sedimentary evaporites are shown to be unimportant from δ11B. This is accounted for two ways: evaporated saline inflow leaks from higher elevation basins and inflows are partly derived from or modified by active volcanic systems. Active and dormant volcanoes plus the massive Altiplano–Puna magmatic body are important as heat sources, which enhance water–rock reactions. The large topographic difference between the mean elevation of Altiplano on which these volcanoes sit and the salar surface allows hydrothermal fluids, which would otherwise stay deep below the surface under the modern arc, to uplift at the salar.

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Section: Background To the Salar De Atacamasupporting

confidence: 72%

Volcanic and Saline Lithium Inputs to the Salar de Atacama

Godfrey

Álvarez-Amado

2020

Minerals

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“…Isotopic data in carbonate lacustrine facies have suggested that moisture coming from the Pacific Ocean influenced the western slopes of the Calama Basin (22.3 S) during the Late MiocenePliocene (de Wet et al, 2015). To the south of Atacama, Negro Francisco Lake (28 S) which is located in the transition to the central Chile climatic region shows evidence of receiving mostly moisture from the Pacific carried by the Southern Westerlies during the Late Holocene (Grosjean et al, 1997).…”

Section: The Origin Of Moisture and Timing Of Wet Episodesmentioning

confidence: 99%

Timing of wet episodes in Atacama Desert over the last 15 ka. The Groundwater Discharge Deposits (GWD) from Domeyko Range at 25°S.

Sáez

Godfrey

Herrera

et al. 2016

Quaternary Science Reviews

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a b s t r a c tA chronologically robust reconstruction of timing and dynamics of millennial time scale wet episodes encompassing the entire Atacama Desert during the last 15 ka has been constructed. To accomplish this, a new composite paleoclimatic record from Groundwater Discharge Deposits (GWD) in the Sierra de Varas (Domeyko Range, southern Atacama in Chile at 25 S) has been compiled and compared with other published paleohydrologic records from the Atacama region. In Sierra de Varas (SV), three millennial timescale wet climate phases have been characterized: around 14.5 ka cal BP, 12.2e9.8 ka cal BP, and 4.7 ka cal BP to the present day. These wet phases are interpreted from intervals of GWD facies formed during periods when the springs were active. GWD facies include: (1) black organic peat, rooted mudstones and sandstones formed in local wetland environments, and (2) gypsum-carbonate rich layers formed by interstitial growth. GWD intervals alternate with gravelly alluvial material deposited during arid phases. A trend towards less humid conditions during the Late Holocene wet episode characterizes GWD sedimentary series in Sierra the Varas, suggesting the onset of a dry episode over the last few centuries. Around 0.7 ka BP a very short wet episode is recorded in the central part of the desert suggesting this was the time of maximum humidity for the entire late Holocene wet period. A brief arid phase occurred between 1.5 and 2.0 ka BP indicated by the absence of GWD in the Domeyko Range. The paleoclimatic reconstruction encompassing the entire Atacama region shows that both the intensity and occurrence of wetter conditions were governed mainly by the distance to the source of moisture, and secondarily by the elevation of the sites. In the northern Atacama (16e20 S), four wet phases fed by N-NE summer monsoon precipitations have been proposed: Tauca phase (18e14 ka cal BP) and Coipasa phase (13e10 ka cal BP) during the Late Glacial, followed by Early Holocene and Late Holocene phases. In contrast, southern Atacama records (23e28 S) display only three pluvial periods which result from SE summer monsoon precipitation and outbreaks from the Westerlies during wintertime. The Early Holocene in the southern Atacama was a period of aridity, generating important landscape differences to those in the Northern Atacama where conditions were wetter. The core of Atacama (20e23 S) is the overall driest part of the desert because it is located in the distal limits of both N-NE and SE sources of moisture, the Amazon Basin and Gran Chaco areas, respectively.

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“…In Calama, the Opache eastern lake and western wetlands developed at a similar time as the Quillagua lake. At least the eastern Opache zone persisted during the first half of Soledad Formation accumulation (Figures 3(b)and 3(c)) [16,57,59]. De Wet et al [57] emphasize that groundwater was the primary input to the Calama's Opache lake and wetlands, initially under semiarid conditions.…”

Section: Paleo-environmental Evolution: Drainage Basins Andmentioning

confidence: 99%

“…These chemical attributes, the lateral continuity of the Quillagua Formation 70 km south of the depocenter along the modern valley of the Loa River into the minor basin near Cerro Batea (Figures 1 and 3), and the relative change at the initiation of the Quillagua Formation to a positive water balance all imply the addition of a new southern source of water to the Quillagua depocenter. Although the Opache Formation facies indicate no integrated Loa surface drainage out of the Calama basin [9,57], groundwater discharge from the westernmost Calama basin is implicated (Figure 3(c)), whose source was the volcanically active Andes.…”

Section: Paleo-environmental Evolution: Drainage Basins Andmentioning

confidence: 99%

Paleoenvironmental Evolution of a Forearc in Response to Forcings by Drainage, Climate, Volcanism, and Tectonics: The Quillagua Depocenter, Chile

Jordan

Quezada²,

Blanco³

et al. 2022

Lithosphere

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The Late Miocene and Pliocene Quillagua depocenter lake system existed in a forearc basin on the west side of the Andes Mountains in northern Chile, alternating between standing-water and salar conditions. Quaternary incision of the Loa River Canyon resulted in bypass of the prior depositional surface and drainage of groundwater from the abandoned depocenter. Systematic regional geological mapping, 32 new chronological constraints on the strata in the basin, outcrop-scale facies analyses, and geophysical data underpin a revised evaluation of the controls on the lake system. The progressive stages, ages, and causes of the Quaternary destruction of the lake system are reconstructed based on mapped distributions of superficial fluvial sediments, chronological studies of terrace deposits, and landform analysis. The lake system occurred at the junction of small catchments draining the slowly rising western Andean foothills and the large paleo-Loa River catchment draining the Andean volcanic arc, during a time span of intense caldera activity. Small magnitude climate variability affected both the hyperarid low elevation sectors and arid upper sectors of the catchments. By 10 Ma, the regional climate was extremely arid, limiting water and sediment to small amounts, and during the Late Miocene and Pliocene, there was no surface-water outlet to the Pacific. Hydrological variations from 9 to 2.6 Ma led to sediment accumulation in variable lake environments, alternating with long hiatuses. Minor deformation within the Quillagua depocenter shifted the topographic axis and groundwater outlets. Simultaneous headward erosion from the Pacific shore captured the Loa River, which triggered large-magnitude incision that persists today. The progression of surface water environmental change was accompanied by changing composition and amount of surface and groundwater, which determined deposition of primary evaporite minerals, extensive diagenesis, and eventually, complex patterns of dissolution expressed as karst.

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Sedimentology and stable isotopes from a lacustrine-to-palustrine limestone deposited in an arid setting, climatic and tectonic factors: Miocene–Pliocene Opache Formation, Atacama Desert, Chile

Cited by 23 publications

References 94 publications

Volcanic and Saline Lithium Inputs to the Salar de Atacama

Volcanic and Saline Lithium Inputs to the Salar de Atacama

Timing of wet episodes in Atacama Desert over the last 15 ka. The Groundwater Discharge Deposits (GWD) from Domeyko Range at 25°S.

Paleoenvironmental Evolution of a Forearc in Response to Forcings by Drainage, Climate, Volcanism, and Tectonics: The Quillagua Depocenter, Chile

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