INENCO   05446
INSTITUTO DE INVESTIGACIONES EN ENERGIA NO CONVENCIONAL
Unidad Ejecutora - UE
artículos
Título:
The origin of an unusual tuff ring of perlitic rhyolite pyroclasts: The last explosive
Autor/es:
TAIT M; CAS RAYMOND; VIRAMONTE J.G.
Revista:
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Año: 2009 vol. 183 p. 1 - 16
ISSN:
0377-0273
Resumen:
A thick sequence of bedded pyroclastic deposits, comprised largely of crystal poor, partially flow-banded
perlite fragments defines the remains of a tuff ring around the eastern margin of the Miocene Ramadas
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cm
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cm
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cm
perlite fragments defines the remains of a tuff ring around the eastern margin of the Miocene Ramadas
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cm
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cm
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cm
perlite fragments defines the remains of a tuff ring around the eastern margin of the Miocene Ramadas
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cm
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cm
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cm
flow-banded
perlite fragments defines the remains of a tuff ring around the eastern margin of the Miocene Ramadas
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cm
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cm
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cm
fines the remains of a tuff ring around the eastern margin of the Miocene Ramadas
Volcanic Centre (RVC), Central Andes, NW Argentina. In numerous quarry exposures, planar bed-forms
dominate, but low-angle cross-stratification, lensoidal truncations and lateral pinching and swelling of cmfication, lensoidal truncations and lateral pinching and swelling of cm
dm scale bed-forms occur, consistent with pyroclastic surge as the dominant transport and depositional
mechanism. Intercalated are mantling, very fine grained, well-sorted, mmcm scale planar ash layers that
represent deposition from pyroclastic fall out and are most likely the products of co-surge ash clouds. Also
observed are thick m-scale, laterally continuous, poorly-sorted horizons that are interpreted as pyroclastic
represent deposition from pyroclastic fall out and are most likely the products of co-surge ash clouds. Also
observed are thick m-scale, laterally continuous, poorly-sorted horizons that are interpreted as pyroclastic
represent deposition from pyroclastic fall out and are most likely the products of co-surge ash clouds. Also
observed are thick m-scale, laterally continuous, poorly-sorted horizons that are interpreted as pyroclastic
fine grained, well-sorted, mmcm scale planar ash layers that
represent deposition from pyroclastic fall out and are most likely the products of co-surge ash clouds. Also
observed are thick m-scale, laterally continuous, poorly-sorted horizons that are interpreted as pyroclastic
flow deposits. Grainsize variations within the N70 m thick succession range from fine ash to coarse lapilli,
with occasional large blocks reaching 20 cm. Clast vesicularities are typically very low. The sequence
constitutes a rhyolitic tuff ring around the proximal margins of the RVC. Stratigraphic relationships indicate
that the tuff ring was developed following cessation of the major plinian eruption phase of the RVC. A series
of pyroclastic density currents and associated ash clouds is inferred to have resulted in the construction of
the rhyolitic tuff ring, with deposition focussed on the eastern and southern margins of the central vent. The
with occasional large blocks reaching 20 cm. Clast vesicularities are typically very low. The sequence
constitutes a rhyolitic tuff ring around the proximal margins of the RVC. Stratigraphic relationships indicate
that the tuff ring was developed following cessation of the major plinian eruption phase of the RVC. A series
of pyroclastic density currents and associated ash clouds is inferred to have resulted in the construction of
the rhyolitic tuff ring, with deposition focussed on the eastern and southern margins of the central vent. The
with occasional large blocks reaching 20 cm. Clast vesicularities are typically very low. The sequence
constitutes a rhyolitic tuff ring around the proximal margins of the RVC. Stratigraphic relationships indicate
that the tuff ring was developed following cessation of the major plinian eruption phase of the RVC. A series
of pyroclastic density currents and associated ash clouds is inferred to have resulted in the construction of
the rhyolitic tuff ring, with deposition focussed on the eastern and southern margins of the central vent. The
ow deposits. Grainsize variations within the N70 m thick succession range from fine ash to coarse lapilli,
with occasional large blocks reaching 20 cm. Clast vesicularities are typically very low. The sequence
constitutes a rhyolitic tuff ring around the proximal margins of the RVC. Stratigraphic relationships indicate
that the tuff ring was developed following cessation of the major plinian eruption phase of the RVC. A series
of pyroclastic density currents and associated ash clouds is inferred to have resulted in the construction of
the rhyolitic tuff ring, with deposition focussed on the eastern and southern margins of the central vent. The
fine-grained nature of the deposits and low clast vesicularity are consistent with some degree of magma:
water interaction during fragmentation. Pervasive perlitic fracturing of clasts found within the tuff deposits
also indicates hydration and an extended, post-depositional hydration of the pyroclastic sequence, due to the
influence of meteoric water, is likely to have occurred, with deposit permeability, clast specific surface and
climate influential in facilitating additional textural modification of pyroclasts.
climate influential in facilitating additional textural modification of pyroclasts.
climate influential in facilitating additional textural modification of pyroclasts.
water interaction during fragmentation. Pervasive perlitic fracturing of clasts found within the tuff deposits
also indicates hydration and an extended, post-depositional hydration of the pyroclastic sequence, due to the
influence of meteoric water, is likely to have occurred, with deposit permeability, clast specific surface and
climate influential in facilitating additional textural modification of pyroclasts.
climate influential in facilitating additional textural modification of pyroclasts.
climate influential in facilitating additional textural modification of pyroclasts.
water interaction during fragmentation. Pervasive perlitic fracturing of clasts found within the tuff deposits
also indicates hydration and an extended, post-depositional hydration of the pyroclastic sequence, due to the
influence of meteoric water, is likely to have occurred, with deposit permeability, clast specific surface and
climate influential in facilitating additional textural modification of pyroclasts.
climate influential in facilitating additional textural modification of pyroclasts.
climate influential in facilitating additional textural modification of pyroclasts.
ne-grained nature of the deposits and low clast vesicularity are consistent with some degree of magma:
water interaction during fragmentation. Pervasive perlitic fracturing of clasts found within the tuff deposits
also indicates hydration and an extended, post-depositional hydration of the pyroclastic sequence, due to the
influence of meteoric water, is likely to have occurred, with deposit permeability, clast specific surface and
climate influential in facilitating additional textural modification of pyroclasts.
climate influential in facilitating additional textural modification of pyroclasts.
climate influential in facilitating additional textural modification of pyroclasts.
fluence of meteoric water, is likely to have occurred, with deposit permeability, clast specific surface and
climate influential in facilitating additional textural modification of pyroclasts.fluential in facilitating additional textural modification of pyroclasts.