Argentina - WMO

Dario Trombotto Liaudat
Geocryology
IPA National Contact
Argentine Sub-Committee of Cryospheric Sciences
IANIGLA – CCT CONICET Mendoza
Argentina
GLOBAL CHRYOSPHERIC WATCH (GCW)
CryoNet South America Workshop
Santiago de Chile, Chile, 27-29 October 2014
Environmental status of the cryogenic permafrost conditions in the last decade in
the Central Andes, one example: Morenas Coloradas rockglacier, Mendoza,
Argentina.
Dario Trombotto Liaudat
1. Introduction
Geocryology is the study of earth materials including rock at temperatures below 0°C. It is
the science that studies the environment and ecology of cold regions, the natural,
geological, physical and chemical processes related to the freezing-thawing cycles, and
the relationship with Permafrost and human activities (Trombotto Liaudat et al, 2014).
The principal goal of the Study and Research of the Geocryology at the IANIGLA institute
is to research frozen ground, to deduce where frozen ground in the Andes occurs, how
and where are the principal cryoforms, that contain permafrost, and to investigate the
cryogenic dynamic processes, that will be affected by climatic changes.
Permafrost is ground (soil or rock and included Ice and organic material) that remains at or
below 0°C for at least two consecutive years. Permafrost is synonymous with perennially
Cryotic Ground: it is defined on the basis of temperature. It is not necessarily frozen,
because the Freezing Point of the included water may be depressed several degrees
below 0°C; moisture in the form of water or Ice may or may not be present. In other words,
whereas all perennially Frozen Ground is Permafrost, not all Permafrost is perennially
frozen. Permafrost should not be regarded as permanent, because natural or man-made
changes in the climate or terrain may cause the temperature of the ground to rise above
0°C (Trombotto Liaudat et al, 2014).
In South America (Figure 1) distinctive cryogenic regions with permafrost were detected by
Trombotto (2000). They were registered considering the MAAT between 0 and -5 ºC. The
regions cannot discriminate glacial ice. Some regions are extra Andean.
An analysis of a cryogenic region in the Central Andes as the Morenas Coloradas
rockglacier shows the presented frozen ground variations since 1989.
A rockglacier (figure 2) is a mass of rock fragments and finer material, on a slope, that
contains either interstitial, pore or/ and injection ice and shows evidence of past or present
movement. It is a cryogenic landform, supersaturated with ice that if active, moves down
slope by the influence of gravity which produces creep and deformation of the mountain
permafrost. Rockglaciers do not form where there is insufficient moisture to form the
interstitial ice that permits movement of the mass. Active rockglaciers possess steep fronts
with slope angles greater than the angle of repose. Most rockglaciers have transverse
ridges and furrows on their surface. In general, rockglaciers present a lobate shape with
surficial morphology similar to a lava flow. However, especially in the Central Andes, the
morphologies can be considerably complex with multiple basins contributing material and
the superposition of two or more lobes.
(Guía Terminológica de la Geocriología Sudamericana / Terminological Guide of the South
American Geocryology, Trombotto Liaudat, Weinstein and Arenson, 2014)
Figure 2: Morenas Coloradas Rockglacier
For the study of the climatic variations in the permafrost special monitoring sites will be
chosen. The sites are revised annually to obtain ground temperatures and the information
of the state of subterranean ice if it occurs, in this last case through different geophysical
methodologies (seismic, geoelectric soundings, GPR). The monitoring depends on
research projects along the Andes as well as on financial and logistic constraints.
A
Location
(m)
Method
Lagunita del Plata, southern slope
Monitoring Site
Cordón del Plata, Cordillera Frontal,
S 33º 02' 51"
4491
Bth, Tex TP
(Mendoza), interrupted (LL5)
Central Andes
W 69º 24' 40"
Lagunita del Plata, northern slope
Cordón del Plata, Cordillera Frontal,
S 33º 03' 46"
(Mendoza), interrupted (LL2)
Central Andes
W 69º 24' 06"
Balcón I (Mendoza)
Cordón del Plata, Cordillera Frontal.
S 32º 57' 43"
Central Andes
W 69º 22' 19"
Balcón I Superior (Mendoza)
Cordón del Plata, Cordillera Frontal,
S 32º 57' 18"
Central Andes
W 69º 22' 14"
Cordón del Plata, Cordillera Frontal,
S 32º 56' 95"
Central Andes
W 69º 22' 49"
Cordillera Frontal, Central Andes
S 34° 14' 48’’
Balcón II (Mendoza)
Glaciar de escombros Dragón
Region
(Mendoza), discontinued
Termistor Cº Laguna (2)
AL
4008
S 34° 11' 00"
3560
3586
3770
3553
3688
Tex, G
TP
Bth, G
AL
D
TP
Bth, G
AL
Bth, D
TP
G, Tex
AL
Bth
TP
Tex
AL
Bth
TP
W 69° 35' 53"
Volcán Peteroa (Mendoza) (1)
Cordillera Principal, Central Andes
S 35º 14' 27"
AL
3489
Bth
W 70º 33' 50"
Glaciar de escombros Pachón
Cordillera Principal, Central Andes
(San Juan)
Gelifluxión N Pachón
Cordillera Principal, Central Andes
Cordillera Principal, Central Andes
S 31º 45' 23"
3816
S 31º 45' 06''
3738
Cordón Rivadavia, Wet Andes
S 42º 50'
1600
W 71º 30'
Cordillera Principal, Central Andes
AL
BD
TP
Tex
AL
BD
TP
Tex
AL
D
TP
S 31º 44' 54'’
3787
BTS
TP
D
AL
D
TP
Tex
depth = 56.1 m, water at 16.5 depth
W 70º 25' 14'’
Cordillera Principal, Central Andes
depth = 5 m, inst = 4 m
Volcán Copahue (Neuquén)
TP
Tex
AL
P 17 - San Juan, inst = 15 m
Pozo 376 (San Juan)
BD
W 70º 25' 47''
air temperature
Sitio Histórico de Aguilar
3846
W 70º 26' 59"
Pozo 352, depth = 15 m
Valle del Silencio (Caradoc, Chubut).
3872
W 70º 27' 03"
Cordillera Principal, Central Andes
(San Juan) ice at 5 m depth
Glaciar de escombros Pit (San Juan)
S 31º 45' 33"
TP
AL
W 70º 25' 12"
(San Juan) ice at 6 m depth
Gelifluxión S Pachón
S 31º 44' 40"
TP
AL
W 69° 31' 08"
Cordillera Principal, Central Andes
Bth, G
S 31º 44' 45.4"
AL
3878
D
W 70º 25' 57.3''
Cordillera Principal, Andes Australes
S 37°50’38.58´´
W 71°06’53.64´´
2095
BTS
Figure 3: Monitoring sites. A = altitude in meters; Tex = extrapolated top of frozen ground depth based on
temperature profile, generally obtained by data logger or thermistors; B = borehole ; th = thermistors; Bth =
borehole and thermistors; D = data loggers; G = with geophysics; TP = Top of permafrost (m); * = No data; N
N = no evidence of permafrost; AL = active layer (m); N/D = disassembled; inst = instrumentation;
(1) Buried ice exists inside the caldera under a volcanic sedimentary cover with a thickness of at least 30 40 cm; (2) Ice in a refuge at 3870 m ASL. In blue the zone of the present report.
2. Methodology
The applied geocryological method is based on the analysis of key or pilote zones of
previously selected (Figure 3) and studied rockglaciers (Trombotto and Borzotta, 2009).
Monitoring sites include rockglaciers where shallow drillings were made, according to the
international classification, to install temperature sensors in the active layer. Sensors
utilized were those calibrated at the institute or data loggers type UTL (accuracy = +/- 0.1
ºC; resolution = 0.27 ºC (8 bit); average frequency = 4 hours), built at the University of
Bern (Switzerland).
The data collected were used to characterize the evolution of the temperatures in the
subsoil, and to determine the presence of permafrost.
In the case of the site Balcón I (3560 m) the thermistors were installed at different depths: 0.05 m, -0.20 m, -0.70 m, -1.20 m, -1.70 m, -2.20 m, -2.70 m, -4.00 m, -5.00 m and at the
site Balcón II (3770 m), at 1.5 m and 3 m depth. In the year 2008 a new drilling (called
Balcón I Superior, 3690 m) was made. Thermistors were installed at 1, 2, 3, 3.25, 4 and
4,70 m. Data loggers were also installed at 3,35 and 4,70 m. Permafrost was detected at c
4.90 m appr., where the drill could not penetrate any deeper.
At Balcón I, an almost continuous record of temperatures was obtained, registered with a
Grant equipment between 1989 and 1992 (frequency = 12 hours). The resolution is 0.25
ºC approximately. In these cases the thermistors were installed in the active layer above
the permafrost table.
In 2005, and once corroborated that the permafrost table did no longer exist at 5 m depth,
permafrost was detected with a hammer drill during different drilling attempts at various
spots of the site without being able to advance and by the characteristic sound caused
when the drill hits a frozen layer. Moreover the temperature of 0°C has been measured
and with the help of a geoelectrical profile the ice-bearing permafrost table could be
located with greater exactness at a depth of 4.9 - 5 m (Trombotto et al., 1999). A new
suface drilling was carried out in 2006, reaching a depth of 6 m. Thermistors were installed
at -2.90, -3.90 and -5.90 m depth in order to keep registering the evolution of temperatures
in the cryogenic soil. New observation sites and more sensors were added in 2006.
Moreover all data were corroborated by new drillings. The drillings were made applying the
method developed by Hernández (2002) with a hammer drill with an external diameter of
2.54 cm and a system of plastic tubes with an internal diameter of 1.58 cm which create a
protection shaft for the sensors which are introduced at a prefixed distance where
ventilation holes of a diameter of 1 cm allow the air circulation at this depth.
Any upward movement would affect the construction and would be identifiable by the
position of the tube and the marked rocks on the surface. As this is not the case, it can be
supposed that the casing is not jacked up. The temperature curves are illustrated and at
the same time optimized or linearly extrapolated looking for the respective permafrost table
according to the available values. A correlation and regression analysis was used to better
estimate the location of the top of permafrost.
Permafrost was detected by either direct methods, that is to say findings and temperature
profiles obtained through the surface drillings mentioned above and geomorphological
deductions, or indirect methods, such as geophysical profiles (geoelectrics and GPR) to
determine the ice-bearing permafrost.
3. Study area: Monitoring site Morenas Coloradas rockglacier
The study area (Figure 4) is situated in the Andean Cordillera of Mendoza, a region
frequently referred to as Central Andes. It comprises the area between 31° and 35° S
approximately. This region belongs to the southernmost part of the Dry Andes. The valley
of Morenas Coloradas, in the Cordón del Plata, Cordillera Frontal, in the Argentine
province of Mendoza was chosen as an outstanding and at the same time representative
cryogenic example of the region.
The valley of Morenas Coloradas (SE) consists of a composed rockglacier, of the tongueshaped type, with interrelated and superimposed frozen bodies consisting of cryogenic
sediments derived from morainic till.
A tiny glacier remains at the tip of the valley but it continues with a covered glacier with a
length of 2.5 km at a height of over 4200m. Moreover, the valley is occupied by a covered
glacier, moraines with ice cores or islands of ice covered by till and one very small section
of uncovered ice at the tip of the valley.
Therefore the rockglacier is considered to be mainly of glacigenic origin. The
cryosediments are derived from the palaeozoic rock, predominantly rhyolites from the
upper palaeozoic age (Caminos, 1979) which outcrop in the mountains. The study area is
situated at the so called high Andean level or Andean tundra (Trombotto, 1991) and on the
active rockglaciers practically no vegetation is found.
Glacigenic rockglaciers often are initiated in complex areas of “transition” or
“periglaciation”, a continuation of the final tongues of covered glaciers. These are “rooting
areas” of rockglaciers (Trombotto, 1991) which may reveal bodies of “dead” ice,
disconnected from the original glaciers. The latter together with the depressions caused by
the fusion of ice denominated thermokarst are indicators for the degradation of glacial ice
(Trombotto et al., 2008).
The closest meteorological station is “Vallecitos” at 2550 m a.s.l. (32° 56’ SL and 69° 23’
WL). Data collection however has been discontinuous. The mean annual air temperature
(MAAT) between 1979 and 1994 was 6.3°C and the mean annual precipitation 442 mm
(1979-1983) registered by totalizers (rain and snow). The period registered between 19881992 was significantly warmer with a MAAT of 7.36°C.
The accumulation of snow on the ground and its interrelation with the “zonda” (a warm dry
wind like the foehn) also is of key importance because this wind impedes snow
accumulation (Trombotto and Borzotta, 2009).
Site Balcón I is situated at the front of this active rockglacier which occupies the main part
of the valley. Site Balcón II is situated on a talus rockglacier superimposed with the main
frozen detritic body of glacigenic origin.
Figure 4: Monitoring sites at the Morenas Coloradas rockglacier
4. Results and Discussions
The trend of mean annual air temperature of Mendoza city shows a general warming
which was also detected in the Central Andes for the same period. Unfortunately the data
of the mountains are insufficient and interrupted (Figure 5 and 6).
Figure 5: Mean annual air temperatures of Mendoza city
Figure 6: Mean annual air temperatures of the Vallecitos Weather station
Presently, the proper glacial area is strongly reduced compared to the inventory of glaciers
based on aerial photographs of 1963 (Corte & Espizúa, 1981), it has to be remarked, that
the exposed glacial ice practically disappeared from the three studied valleys (Figure 4).
The valleys begin with covered ice ending in the „root area“, where the composed
rockglacier is generated (Barsch & King, 1989; Trombotto, 1991).
The following figure 6 shows the position of the top of the permafrost in the above
mentioned monitoring sites.
4.1.
Balcón I
This study area was chosen because of its accessibility and because regional studies had
been carried out there since 1989 (figure 7), but with some interruptions between 1992
and 1999. The terminal part of this mesoform has continuously been monitored since 1999.
Furthermore soil temperatures at a height of approximatly 3800 m a.s.l. have been
monitored since 2001 in the same valley.
Figure 7: Balcón I, top of the permafrost between the years 1989 and 1992.
Between 2004 and 2007 the permafrost table was estimated between 7.5 m and almost 9
m depth. The upper part of the curves displays daily temperature oscillations and a
retarding of the minima of up to 1 m depth (compare Trombotto 1991). The nose of
Morenas Coloradas, that is the site called Balcón I, already expresses inactivity; the
permafrost table is found at great depth.
Results indicated that thaw deepened at a rate of approximately 25 cm per year assuming
a regular gradual increase between 1992 and 2007. This means that an unfrozen layer is
found now around 3.5 m deeper in the ground.
The new domain between the old position and the new positions of the permafrost table
might belong to a “transient layer” located between the active layer and the permafrost
table (Trombotto and Borzotta, 2009).
Between 2008 and 2013 the 0 ºC level in the ground is located between 7.6 and 8.6 m
deep, at similar conditions as before. The rise of the 0 ºC level noticed in the previous
period (2006-2008) is followed by a decline or warmer temperatures and then the curve
shows another slight increase (Figure 8 and 9). This irregularity suggests instability in the
transient layer because of the location of the monitoring site at the foot of another
overlapping active frozen body that must supply thaw water in summer.
Figure 8: Balcón I
Figure 9: Variations of the 0 ºC level in the depth at the Balcón I
4.2.
Balcón II
The top of permafrost was determined by drilling to the maximum possibility of penetration
and with thermistors and data loggers when they reached the temperature of 0 C°. The
motion of the top of permafrost calculated after two consecutive years of its occurrence,
shows variations with a general downward trend. This calculation was made through the
prolongation of the curve of the warmest month which is March, in a few centimeters in
depth until cutting the 0 ºC axis.
Between 2002-2004 at Balcón II the deepening together with the deterioration of the
permafrost was approximately15 cm per year according to the registers mentioned above.
At Balcón II, permafrost was found at a depth of 3 m in 2001. By the end of the summer of
2004 however, thaw deepened by approximately 30 cm. The temperatures are positive
(between 0.13° and 0.36° C) at 3 m depth between 2004 and 2007 (Trombotto and
Borzotta, 2009).
Thermokarst appears clearly active in the surroundings of Balcón II and particularly from a
height of 3800m approximately upwards.
During 2008 and 2013 a gradual deepening of the top of the permafrost until 3.35 m can
be detected (Figure 8). Between the years 2005 and 2008 no warming was observed
(Figure 10).
In figure 10 it is possible to observe the intersection of the warmest and the coldest
months during 2004 and 2013 and its slight movement towards the 0 ºC axis which is also
to be considered as a possible sign of imbalance of the supra-permafrost.
Figure 10: Balcón II
4.1.
Balcón I Superior
This monitoring site starts in 2008 but as shown in figure 6, it displays a gradual
degradation of the supra-permafrost.
If the intersection of the warmest and the coldest month during the studied years is
observed, and considering that it is not exactly the point of zero amplitude that should be
deeper (for which supra-permafrost temperatures are needed), but important for its
orientation in depth, a slight movement of them towards the 0 ºC axis is identified. This last
consideration might be interpreted as a sign of unsteady condition of the degrading suprapermafrost.
Figure 11: Balcón I Superior. Different positions of the top of the permafrost between 2008
and 2013.
5. General Conclusions
A general trend of deepening of active layers in the monitoring sites of the valley of the
Morenas Coloradas rockglacier is observed. This depth is consistent with the curves of air
temperature at different locations in the province of Mendoza.
In altitude, the lower part of the mentioned rockglacier shows to be more affected by the
general warming process. This last effect can also be understood because of two
phenomena: the greatest warming of the year might be reinforced by the increase in
altitude of the 0 ºC isotherm (see Trombotto et al. 1997).
References
Barsch, D., King, L., 1989. Origin and geoelectrical resistivity of rock glaciers in semi-arid
subtropical mountains (Andes of Mendoza, Argentina). Z. Geomorph.N.F., Vol. 33, 2,
p. 151-163.
Corte, A.E., Espizúa, L., 1981. Inventario de Glaciares de la Cuenca del Río Mendoza.
IANIGLA – CONICET, Imprenta Farras. Mendoza.
Hernández, J., 2002. Perforadora a percusión para suelos detríticos criogénicos. En
“IANIGLA, 1973-2003: 30 años de Investigación Básica y Aplicada en Ciencias
Ambientales” (Trombotto, D y Villalba, R; editores). Editorial ZETA, p. 71-72.
Mendoza.
Trombotto, D., 1991. Untersuchungen zum periglazialen Formenschatz und zu
periglazialen Sedimenten in der “Lagunita del Plata”, Mendoza, Argentinien.
Heidelberger Geographische Arbeiten, Vol. 90, 171 p.
Trombotto, D., 2000. Survey of Cryogenic Processes, Periglacial Forms and Permafrost
Conditions in South America. Revista do Instituto Geológico, Vol. 21, Nr.1/2, p. 33-55.
São Paulo, Brasil.
Trombotto, D., Buk., E. & Hernández, J. 1997. "Monitoring of Mountain Permafrost in the
Central Andes, Argentina". Permafrost and Periglacial Processes, Vol. 8: 123 –129,
Wiley & Sons, Chichester, West Sussex, UK.
Trombotto, D., Buk, E., Hernández, J., 1999. Rock glaciers in the Southern Central Andes
(approx. 33°–34°S), Cordillera Frontal, Mendoza, Argentina. Bamberger Geogr.
Schriften, Vol. 19, p. 145-173.
Trombotto Liaudat, D., Arena, L. & Caranti, G., 2008. Glacial Ice as Cryogenic Factor in
the Periglaciation Zone of the omposed Rockglacier Morenas Coloradas, Central
Andes of Mendoza, Argentina. Ninth International Conference on Permafrost,
Fairbanks, Alaska, Proceedings, Vol. 2, p. 1781-1786.
Trombotto, D. & Borzotta, E. 2009. “Indicators of present global warming through changes
in active layer-thickness, estimation of thermal difussivity anf geomorphological
observations in the Morenas Coloradas rock glacier, Central Andes of Mendoza, Dry
Andes, Argentina”. Cold Regions Science and Technology, 55: 321-330. Elsevier,
The Netherlands. (versión on line en 2008).
Trombotto Liaudat, D., P. Wainstein y L. U. Arenson. 2014. “Guía Terminológica de la
Geocriología Sudamericana” / "Terminological Guide of the South American
Geocryology”. Vázquez Mazzini Editores, 128 páginas, Buenos Aires.
A. Background Document
El “background document” tiene como finalidad describir las mediciones y/o el plan de
investigación (referido a observaciones terrestres) en que Ud. o vuestra organización
están involucrados. Otros detalles del/los sitio/s de medición deberán ser ingresados en el
cuestionario (ver abajo). Favor incluir lo siguiente:
A. Breve descripción del sitio/los sitios o programa de mediciones
Ver Report Frozen Ground Argentina Trombotto
Figura 3
B. Organzación patrocinante/auspiciadora de las mediciones (agencia nacional,
universidad, empresa privada, etc.)
Ver Report Frozen Ground Argentina Trombotto. Página 1.
Unidad de Geocriología, CONICET. A través de proyectos de investigación.
C. Redes nacionales o internacionales relevantes al/los sitio/s de medición, en caso de
existir
Asociación Argentina y Sudaméricana de Permafrost (AASP) (International Permafrost
Association). Centro de Estudios Avanzados en Zonas Áridas (CEAZA), La Serena, Chile.
Inventario de glaciares de escombros de Bolivia (en conjunto con la Université de Savoie,
Francia). Colaboración técnica con la Universidad de Rio de Janeiro.
D. Componentes de la criósfera involucradas en la/las medición/es (nieve, glaciares, hielo
marino, permafrost, hielos continentales, plataformas flotsantes de hielo, hielo lacustre,
hielo fluvial)
Permafrost, manchones de nieve perennes, glaciares cubiertos, glaciares
E. Perspectivas futuras de su/s sitio/s: existe la visión/compromiso de mantenerlo/s en el
largo plazo, o por el contrario corresponde a un plan de corto plazo?
En la medida que se pueda a largo plazo, depende de los proyectos de investigación que
involucren a los sitios de monitoreo
Sería útil si Ud. pudiese asimismo responder las siguientes interrogantes:
1.
Cómo podría CryoNet ayudar a lograr sus intereses nacionales/regionales/globales?
Apoyar económicamente los proyectos de investigación que se llevan a acabo y que
involucran la compra de equipos como data loggers o la fabricación de perforadoras.
2.
Qué podría Ud. o su organización contribuir a la implementación de CryoNet?
Contribuir con los resultados a la red mundial
3. Cuáles son los beneficios que esperaría de CryoNet: (por ejemplo para los
operadores, operadores de las redes de investigación, la comunidad científica, tomadores
de decisión, monitoreo ambiental y modelación, proveedores de datos satelitales, etc.)?
Facilitación de imágenes satelitales
4. Cuáles serían a su juicio áreas faltantes en observaciones criosféricas (por ejemplo
vacíos temáticos, espaciales, temporales, disponibilidad de datos, intercambio de datos,
política de manejo de datos, etc.) y cómo podría CryoNet ayudar a solucionar esto?
Disponibilidad de datos, estaciones meteorológicas poco confiables
5. Favor priorizar las actividades de CryoNet de acuerdo a su visión personal (indicar
ALTO/MEDIO/BAJO para cada punto):
Establecimiento de la red CryoNet
Alto
Estándares, guías y entrenamiento para realizar observaciones
Medio
Experimentos de inter-comparación (por ejemplo sensores, métodos)
Medio
Cooperación con redes existentes
Alto
Política de datos relativa a su archivo, accesibilidad e intercambio
Medio
Apoyo a necesidades nacionales.
Alto
6. Favor compartir cualquier otro planteamiento que Ud. tenga relativo para
consideración de los participantes del Taller