A new Miocene Formation from The Peotillos-Tolentino Graben fill, Western Sierra Madre Oriental at San Luis Potosi, Mexico: Part 1, Geology
Por:
Ferrusquia-Villafranca, Ismael, Ruiz-Gonzalez, Jose E., Torres-Hernandez, Jose Ramon, Martinez-Hernandez, Enrique, Gama-Castro, Jorge
Publicada:
1 ene 2016
Categoría:
Earth and Planetary Sciences (miscellaneous)
Resumen:
In spite of similar to 130 years of geologic research in Mexico, much
remains pending e.g. only 1/3 of this country's territory is mapped in
detail [i.e., scale 1: 50000], the formal stratigraphic
differentiation of the continental sedimentary Cenozoic is barely
started, discriminating the depositional systems that make up basic
units is even less pursued. Towards filling this gap, the detailed
Cenozoic lithostratigraphy of a graben fill in central-east Mexico is
reviewed, a new Miocene formation is proposed, and its importance in
understanding the regional geologic evolution is discussed.
The study area lies in San Luis Potosi State, within the Sierra Madre
Oriental Morphotectonic Province [SMO], between 22 degrees 11'-22
degrees 19'N Lat. and 100 degrees 30'-100 degrees 39'W Long., and 1295 -
2025 masl. The similar to 1200 m thick Tertiary sedimentary sequence is
preserved in the N-S trending Peotillos-Tolentino Graben, which is bound
by horsts of folded and faulted Cretaceous carbonate units; it includes
a Paleogene volcanic succession formed by an andesitic-basaltic lavic
stack intertongued/overlain by a rhyolitic ash flow-tuff sheet, which
non-conformably underlies the new unit, a Late Miocene, similar to 1100
m thick, fluvio-lacustrine, largely calcilithitic, 15 degrees - 20
degrees NE dipping, peneplained sequence, in turn unconformably overlain
by a Quaternary, similar to 40 m thick, calcilithitic-volcarenitic
blanket; locally overlain by mafic lavic/pyroclastic rocks.
The new formation was deposited in a subsiding basin, under humid to
subhumid conditions allowing erosion of large clastics volumes, and the
development of an axial fluvial network, capable of
transporting/depositing such volumes. Nevertheless, floodplain calcisols
and calcretes indicate periods of dry conditions. The similar to 1100 m
thick, largely fluvial stratal pile thus formed, records cyclic
superimposing of such network's systems during Late Miocene time; this
in turn, denotes stability of the tectono-sedimentary-climatic
conditions. Subsequently, faulting, erosion and finally peneplanation
took place. In the Quaternary, clastic sedimentation was reestablished.
The holistic approach used to study the Peotillos-Tolentino Graben and
its sedimentary fill, could be applied to the other post-orogenic basins
of the Sierra Madre Oriental that bear Cenozoic clastic sequences,
probably resulting from similar processes, to identify and characterize
such processes, thus contributing to a better understanding of the
Cenozoic geologic makeup and evolution of this province.
Filiaciones:
Ferrusquia-Villafranca, Ismael:
Univ Nacl Autonoma Mexico, Inst Geol, Ciudad Univ, Ciudad De Mexico 04510, Mexico
Ruiz-Gonzalez, Jose E.:
Univ Nacl Autonoma Mexico, Inst Geol, Ciudad Univ, Ciudad De Mexico 04510, Mexico
Torres-Hernandez, Jose Ramon:
Univ Autonoma San Luis Potosi, Inst Geol, Ciudad Univ, San Luis Potosi 78000, Slp, Mexico
Martinez-Hernandez, Enrique:
Univ Nacl Autonoma Mexico, Inst Geol, Ciudad Univ, Ciudad De Mexico 04510, Mexico
Gama-Castro, Jorge:
Univ Nacl Autonoma Mexico, Inst Geol, Ciudad Univ, Ciudad De Mexico 04510, Mexico
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