1. CUEXCOMATE: FROM THE SMALLEST VOLCANO TO THE BIGGEST GEYSER ON EARTH
Institute of Geology, UNAM. Ciudad Universitaria, 04510 Mexico DF Hugo Beraldi-Campesi hberaldi@unam.mx
SUMMARY
Completely surrounded by urban development in the city of Puebla, Mexico, the Cuexcomate (from the Náhuatl ‘cuexcomatl’, meaning
‘bucket’ or ‘pot’) geyser cone deposit has been mistakenly believed to be a ‘small volcano’ by the local population for centuries. The
concept of ‘volcano’ was coined because of its dome-shaped exterior and its central crater, similar to a volcano.
The Cuexcomate is a chemical (calcitic) hydrothermal deposit (geyserite) of considerable size: ~28.5 x 24.3 m in diameter, stands ~8.4 m
above the ground, and its ~10 x 5 m-diameter internal crater goes down ~4 m below ground (total depth ~12 m). The roomy interior
serves as cultural/touristic attraction. Ambient-temperature water still flows in the bottom interior, connecting with a natural underground
discharge of unknown path.
Although no absolute ages are known for the Cuexcomate, Puebla’s municipal government sustains that the Cuexcomate was originated
~948 years ago, in 1064, and was reactivated ~349 years ago, in 1664. Important peaks of activity of the Popocatépetl volcano (~40 km
to the West of Cuexcomate) before the year 1900, occur approximately 349, 493, and 5712 years ago. It is unclear whether the
Cuexcomate was formed during Popocatépetl’s mild activity or not. Radiometric dating is needed.
The Cuexcomate clearly had a hydrothermal origin. It can be compared in shape, texture, and composition to analog, currently-active
geysers around the world. Yet none compares in size with the Cuexcomate; the largest being ~5 m tall. The non-reported-yet Apaseo
sinters (North of the Trans-Mexican Volcanic Belt) are used here to compare different mineralogical compositions (Cuexcomate = 90 %
calcite, Apaseo sinters = 90% amorphous silica) with similar shapes and origins, typical of hydrothermal deposits in which the
underground basement defines the composition of the precipitates. Data on Cuexcomate’s chemical composition are presented here for
the first time.
CONCLUSIONS
-The Cuexcomate represents the oldest evidence of hydrothermal activity
reported for the Popocatepetl volcano.
-Because the Cuexcomate had a hydrothermal origin, it denies the historical
idea that cuexcomate is a volcano.
-The Cuexcomate is established here as a geyserite deposit of 90 % calcitic
composition.
ACKNOWLEDGEMENTS
This study was possible thanks to Puebla’s City Council, Carnes Canet Miquel, Institute of
Geophysics, UNAM, and Teresa Pi Puig, Institute of Geology, UNAM.
Popocatépetl
5426 masl
Last active: 2012
Iztaccíhuatl
5230 masl
Last active: >80,000 yr BP?
La Malinche
4461 masl
Last active: 3182 yr BP
Puebla
2
4
6
8
10
-7500 -6000 -4500 -3000 -1500 0 1500
EruptiveCharacteristics
Eruptive Characteristics:
1. Central vent eruption
2. Explosive eruption
3. Pyroclastic flow(s)
4. Lava flow(s)
5. Lava dome extrusion
6. Fatalities
7. Damage (land, property, etc.)
8. Mudflow(s) (lahars)
9. Evacuation
Birth of Cuexcomate?
1064
1996
Time (years)
Eruptive history of the Popocatépetl volcano
Data from the Global Volcanism Program (GVP). http://www.volcano.si.edu/info/
2
4
6
8
10
-7500 -6000 -4500 -3000 -1500 0 1500
EruptiveCharacteristics
Eruptive Characteristics:
1. Central vent eruption
2. Explosive eruption
3. Pyroclastic flow(s)
4. Lava flow(s)
5. Lava dome extrusion
6. Fatalities
7. Damage (land, property, etc.)
8. Mudflow(s) (lahars)
9. Evacuation
Birth of Cuexcomate?
1064
1996
Time (years)
Eruptive history of the Popocatépetl volcano
Data from the Global Volcanism Program (GVP). http://www.volcano.si.edu/info/
1
2
3
4
5
1300 1400 1500 1600 1700 1800 1900 2000
RelativeExplosivityIndex
Time (years)
9
1519
Birth of Cuexcomate?
1663
19191919
1996
Eruptive characteristics vs. Volcanic Explosivity Index
EC
VEI
Data from http://www.volcano.si.edu/info/
1
2
3
4
5
1300 1400 1500 1600 1700 1800 1900 2000
RelativeExplosivityIndex
Time (years)
9
1519
Reactivation of Cuexcomate?
1663
19191919
1996
Eruptive characteristics vs. Volcanic Explosivity Index
EC
VEI
Data from http://www.volcano.si.edu/info/
Weathered texture
3 m
Ground level
~12m
flow
Crater
01
04
03
02
05
Cuexcomate seen from above.
Courtesy of Google Earth.
Wikipedia.com
Viajeros.com
0
0.2
0.4
0.6
0.8
350 850 1350 1850 2350
Wavelength nm
Absorbance%
01. Base
02. 5 m
03. 1.3 m
04. 1 m
05. Exterior
06. 300 m apart
1445 1937 2354
0.1
0.2
0.3
0.4
0.5
350 850 1350 1850 2350
Wavelength
Absorbance%
Cuexcomate
Apaseo
0
500
1000
1500
2000
2500
4 9 14 19 24 29 34 39 44 49 54 59 64 69
2 degrees
Counts
Cuexcomate, exterior upper surface
Calcite
Calcite
Calcite
Calcite
Calcite
Calcite
Calcite
-500
0
500
1000
1500
2000
2500
4 9 14 19 24 29 34 39 44 49 54 59 64 69
2 Theta degrees
Counts
Cuexcomate XRD
Sinter A072
Calcite
Tridimite
Amorphous
silica
Punch Bowl Geyser, Yellowstone National Park
Castle Geyser, Yellowstone National Park Fly Ranch Geyser, Nevada, US
Taupo, New Zeland
Castle Geyser, Yellowstone National Park
Pool geyser
Taupo, New Zeland
Active geysers
Inactive geysers
Sinter deposits Hot pools and
terraces
1100° C
500° C
400° C
300° C
200° C
0
km
1
2
Ascending
Hot water
6 m
6 m
2 m
1 m
Apaseo geyserite sinters
