ictja - copernicus.orgsources: esri, usgs, noaa cueros de purulla nevado de tres cruces cerro blanco...
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How to cite: Fernandez-Turiel J. L., Perez-Torrado F. J., Rodriguez-Gonzalez A., Ratto N., Rejas M., Lobo A., 2020. The 4.2 ka cal BP major eruption of Cerro Blanco, Central Andes. EGU General Assembly 2020, 4-8 May, Vienna, Austria. EGU2020-5038. https://doi.org/10.5194/egusphere-egu2020-5038.
ICTJA
EGU2020-5038
QUECA¹Institute of Earth Sciences Jaume Almera, ICTJA, CSIC, Barcelona, Spain ([email protected], [email protected], [email protected])2Instituto de Estudios Ambientales y Recursos Naturales (i–UNAT), Universidad de Las Palmas de Gran Canaria (ULPGC), Las Palmas de Gran Canaria, Spain ([email protected], [email protected])3Universidad de Buenos Aires, Instituto de las Culturas (UBA-CONICET), Facultad de Filosofía y Letras, Buenos Aires, Argentina ([email protected])
J.L. Fernandez-Turiel1, F.J. Perez-Torrado2, A. Rodriguez-Gonzalez2, N. Ratto3, M. Rejas1, A. Lobo1
The 4.2 ka cal BP major eruption of Cerro Blanco, Central Andes
Introduction
BdF
CB
CdP
ca. 7820 AP
ca. 4200 a cal AP
ca. 1700 a cal BP(?)
The major eruption of the Cerro Blanco Volca-nic Complex (CBVC), in the Central Volcanic Zone of the Andes, NW Argentina, dated at 4410–4150 a cal BP, is the most important of the three major Holoce-ne felsic eruptive events identified in the sou-thern Puna (Fernan-dez-Turiel et al., 2019).
5000km
30º
20º S
70º 60º W
Sources: Esri, USGS, NOAA
Cueros de Purulla
Nevado de Tres CrucesCerro Blanco
Volcanic Complex
La Paz
Altiplano-Punaplateau
Santiago Buenos Aires
CentralVolcanicZone
CVZ
NVZ
SVZ
AVZ
ARGE
NTIN
A
a
b
a
0 50km
27º
26º S
68º 67º 66º 65º 64º W
Catamarca
Tucumán
Santiagodel Estero
Salta
CdP
CBVC
NTC
La Rioja
Tafí del Valle
Cafayate
Tolombón
Santa María
Calch
aquí
Vall
eys
Bolsón de Fiambalá
El Peñón
AguilaresTermas deRío Hondo
Antofagastade la Sierra
Las Papas
Fiambalá
San Miguel de Tucumán
Santiago del Estero
CHILE
Southern Puna
ARGENTINA
Bolsón de Fiambalá sequence
Eruptive center
Cerro Blanco sequenceCueros de Purulla sequence
b
CB34
CB1
CB33
CB31
CB32
b
Source: Esri, DeLorme, USGS, NPS; Source: Esri, DigitalGlobe,GeoEye, Earthstar, Geographics, CNES/Airbus DS, USDA, USGS,AeroGRID, IGN, and the GIS User Community
0 5 km
N
ENC
RC
CBC
PSBC
CB32
CB1
CB31
CB33CB34
CB23 CB22
26°50'
26°45' S
67°50' 67°45' 67°40' W
a
(a) Holocene volcanic centres in the Andean Central Volcanic Zone (data from Global Volcanism Program); NVZ, Northern Volcanic Zone; CVZ, Central Volcanic Zone; SVZ, Southern Vol-canic Zone; and AVZ, Austral Volcanic Zone. (b) Studied sec-tions and eruptive centres (CdP, Cueros de Purulla; CBVC, Cerro Blanco Volcanic Complex; NTC, Nevado Tres Cruces).
(a) Cerro Blanco Volcanic Complex showing El Niño Caldera (ENC), Pie de San Buenaventura Caldera (PSBC), Robledo Caldera (RC), and Cerro Blanco Cal-dera (CBC); (b) stratigraphic units in the Cerro Blanco Volcanic Complex.
Cerro Blanco Caldera - 5 km diameter
CdP CB BdF
ResultsStratigraphic summary
Sequence Unit Sub-unit Lithofacies and interpretation Mineralogy
Bolsón de Fiambalá
BdF1 Alternating layers of moderate-poorly sorted, dacitic pumice lapilli and ash. Plinian fall deposit.
glass >> plagioclase, biotite, amphiboles, quartz >> magnetite, ilmenite, apatite, titanite
Cerro Blanco CB3 (postcaldera)
4 Alternating layers, 3-30 cm thick, of siliceous sinter. Deposits of hot springs.
amorphous silica
3 Poorly defined decimetric-scale stratified deposits, poorly to very poorly sorted, with decimetric angular rhyolitic blocks in rhyolitic lapilli and coarse ash matrix deposits. Block-and-ash deposits.
glass >> feldspars, quartz, biotite, magnetite, ilmemite >> apatite, allanite-epidote, zircon
2 Poorly to well–defined layers, 3-30 cm thick, white, rhyolitic lapilli and ash deposits. Fallout and phreatomagmatic deposits.
1 Crystal poor, very vesicular, rhyolite lava domes.
CB2 (syncaldera)
3 Unstratified, matrix-supported, moderate to poorly sorted rhyolitic ignimbrite with clasts dominated by coarse pumice lapilli. Pyroclastic density current (PDC) deposits.
glass >> feldspars, quartz, biotite, magnetite, ilmenite > clinopyroxene, orthopyroxene, amphiboles > allanite-epidote, muscovite, titanite, zircon
2 Unstratified rhyolitic ash. Plinian fall deposit.
1 Alternating layers, 1-3 cm thick, some of lapilli and some of ash. Rhyolitic Plinian fall deposit.
CB1 (precaldera)
Poorly stratified lithic-rich breccia. Block-and-ash deposit. glass >> feldspars, quartz, biotite, magnetite, ilmenite
Cueros de Purulla
CdP2 1,2 Unstratified, matrix-supported, moderate to poorly sorted ignimbrite with clasts dominated by coarse pumice lapilli in CdP21 and lithic-rich CdP22. Pyroclastic density current (PDC) deposits.
glass >> feldspars, quartz, biotite, magnetite, ilmenite > apatite, allanite-epidote, muscovite, titanite, zircon
CdP1 Alternating layers, 1-10 cm thick, some of lapilli and some of ash. Rhyolitic Plinian fall deposit.
glass >> feldspars, quartz, biotite, magnetite, ilmenite > amphiboles, clinopyroxene > apatite, allanite-epidote, muscovite, titanite, zircon
1
CB23
CB23
CB23
CB23
b
4410-4150 a cal BP
4440-4240 a cal BP
Ignimbrites of Cerro BlancoCB23 (≈15 km3)
CB2201
2 m
CB22
reworked
CB21
CB22
CB21
CB22
CB21
CB22
CB21
CB22
CB21
CB22CB21
4880-4780 a cal BP
CB22
reworked
0
5
10 cm
0
0.5
1.0 m0
25
50 cm
155 km 169 km 204 km 204 km
208 km
208 km 200 km 200 km 370 km
Fig. 12d
11.4 m -
CB11434 km
23.6 m -
CB11627 km
- 12.5 m
CB11822 km
CB0111 km
CB37155 km CB38
155 km
CB39164 km
CB40169 km
CB41172 km
CB47196 km
CB46200 km
CB50200 km
CB44204 km
CB45208 km
CB53338 km
CB54370 km
0.0
0.5
1.0
1.5
2.0 m
Not t
o sc
ale
fall depositseast of Cerro Blanco
PDC depositssouth of Cerro Blanco
vent
CB54370 km
topsoil - light brown silt to sand, or stony
CB22 unstratified ash
CB21 alternating layers of lapilli and ash
alluvial deposits
colluvial deposits
dating sample
section number and distance to vent
peat and silt lacustrine deposits
loess deposits
palaeosol
CB23 ignimbrite
Plinean fall depositsCB1-23 (≈170 km3)
Bimodal particle size
par�culate cored cluster
corepar�cle
shell par�cle
20 µm
Particle size bimodality is interpreted as evidence of particle aggre-gation in the eruptive plume, forming cored ash clusters that typica-lly break on impact with the ground. The resulting fallout deposit is made up of core particles of hundreds of microns in size and shell particles of tens of microns in diameter that covered the former.
SEM image of distal thin-bedded ash (CB21 sub-unit)
Geochemistry
Two different composi-tions of plagioclases, bio-tite, and Fe–Ti oxides ob-served in the CB2 syn–cal-dera sub–units indicate mixing of two magma batches during the erup-tion.
Isopach maps
50 1000km
0.10
0.10
0.20
0.20
0.30
0.40
0.50
0.600.80
0.80
1
1
Antofagastade la Sierra
Cafayate
Tafí del Valle
Fiambalá
Santiagodel Estero
0.50
0.30
0.30
100
0.34
0.200.40
0.57
0.32 0.351
10.600.60
1.50
2.38
0.50
0.15
0.40
0.08
1.820.600.20
0.68
Formosa
Salta
Jujuy
Chaco
Misiones
Corrientes
Entre Ríos
Santa Fe
Córdoba
San LuisMendoza
San Juan
La Rioja
Santiago del Estero
Catamarca
Tucumán
Paraguay
Paraguay
Brazil
Chile
Uruguay
Bolivia
Laguna MarChiquita
0.100.20
0.300.40
0.500.600.80
10.801
0 100 200km
Sources: Esri, USGS, NOAA
30º S
25º
65º 60º W 55º W
b
Argentina
Atlant
ic Oce
an
Brazil
Chile
Paraguay
Uruguay
Bolivia
Paci
fic O
cean
a
b
sqrt (area) (km)
thic
knes
s (m
)
a
b c
Isopach maps (m) for the CB1-2 fall deposits of CBVC: (a) showing up to the inferred area of 0.10 m isopach, and (b) in the sampled area indicating the measured thickness. (c) Semi–log plot of thic-kness vs. (area)1/2 shows the best fit model (Wei-bull) for isopach adjust-ment.
Eruption modelling
p (deposition > 1 kg/m2
11,000 daily eruptive events(~30 years of wind data)
Modelled with Tephra2Plume height 27,000 m
Secondary thickening We hypothesized that secondary thickening is related to the effect of the topographically induced turbu-lences in the disaggregation, e.g., the breaking of lee waves, genera-ted by winds passing over elevated topography beneath the eruption plume, and to a minor effect of ups-lope moisture transport by easterly atmospheric flow. CBVC, Cerro Blanco Volcanic Complex, CdP, Cueros de Purulla, NTC, Nevado Tres Cruces.
Conclusions● These results change the paradigm of Holo-cene volcanism of southern Puna in the Cen-tral Volcanic Zone of the Andes (CVZ).
● CBVC generated the largest documented eruption during the past five millennia in the CVZ and around the world.
● The 4.2 cal ka Cerro Blanco eruption of mag-nitude 7.0 erupted ~170 km3 tephra over ~500,000 km2, and ~15 km3 ignimbrites.
● The ash deposits of this eruption are exten-sive regional chronostratigraphic markers in South America, and the cryptotephra for the South Hemisphere.
● Further interdisciplinary research should be performed to analyse impacts in local environ-ments and local communities.
DRE volume from VOGRIPA-LAMEVE, except for Toba (Costa et al., 2014) and Cerro Blanco
ReferencesFernandez–Turiel, J.L., Perez–Torrado F.J., Rodriguez–Gonzalez A., Saavedra J., Carracedo J.C., Rejas M., Lobo A., Osterrieth M., Carrizo J.I., Esteban G., Gallardo J., Ratto N., 2019. The large eruption 4.2 ka cal BP in Cerro Blanco, Central Vol-canic Zone, Andes: Insights to the Holocene eruptive deposits in the southern Puna and adjacent regions. Estudios Geologicos, 75, e088. http://estudios-geol.revistas.csic.es/index.php/estudiosgeol/article/view/982/1200
Costa A., Smith V.C., Macedonio G., Matthews N.E., 2014. The magnitude and impact of the Youngest Toba Tuff super-eruption. Frontiers in Earth Science, 2.
AcknowledgementsFinancial support was provided by the ASH and QUECA Projects (MINECO, CGL2008–00099 andCGL2011–23307). We acknowledge the assistance in the analytical work of labGEOTOPGeochemistry Laboratory (infrastructure co–funded by ERDF–EU Ref. CSIC08–4E–001) and DRXLaboratory (infrastructure co–funded by ERDF–EU Ref. CSIC10–4E–141) (J. Ibañez, J. Elvira and S. Alvarez) of ICTJA-CSIC, and EPMA and SEM Laboratories of CCiTUB (X. Llovet and J. Garcia Veigas), and J. Cortés in communication.