ESTRATIGRAFÍA

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StratigraphyThe STUDY OF THE VERTICAL SEQUENCE OF THE LAYERED ROCKS AND THE LATERAL VARIATIONS OF INDIVIDUAL BEDS ON A REGIONAL BASIS (Baars & Stevenson, 1991).

AGI’s Dictionary of Geological Terms in 1976 defines stratigraphy as that BRANCH OF GEOLOGY THAT TREATS THE FORMATION, COMPOSITION, SEQUENCE AND CORRELATION OF STRATIFIED ROCKS as part of the earth’s crust. Sequence stratigraphy is used to interpret the origin of these stata.

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Geologic time scaleA CHRONOLOGICAL CHART OF THE STAGES AND AGES OF

EVENTS in the history of the Earth, from its initial formation to present,

that has been constructed on the basis of the rock record. As is the typical

natural position of rocks, the oldest event is at the bottom of the chart and

the youngest is at the top. Both absolute and relative ages of rocks and

fossils supplement interpretations from rocks. The vastness of geologic

time and the slowness of geological processes are difficult to capture in a

simple chart

StratigraphyThe study of the history, composition, relative ages and distribution of strata, and the interpretation of strata to elucidate Earth history. The comparison, or correlation, of separated strata can include study of their lithology, fossil content, and relative or absolute age, or lithostratigraphy, biostratigraphy, and chronostratigraphy.

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UNIDAD ESTRATIGRÁFICA Es el VOLUMEN QUE OCUPAN LOS SEDIMENTOS DE IGUAL LITOLOGÍA. En una

unidad estratigráfica están presente materiales de diferentes medios sedimentarios y de facies diversas.

FACIESEl concepto de facies, fue introducido en 1838 por Gressly para definir a la SUMA

TOTAL DE LOS ASPECTOS LITOLÓGICOS Y PALEONTOLÓGICOS DE UNA UNIDAD ESTRATIGRÁFICA.

FACIES DESCRIPTIVAS se refieren al aspecto externo del estrato o conjunto de estratos. Esta definición debe hacerse a partir de los rasgos observables en las mismas (litología, textura, color, estructuras sedimentarias, geometría, fósiles)

LITOFACIESSe usa para definir los aspectos litológicos de un conjunto de estratos y

correlativamente para las condiciones físico-químicas que estuvieron presentes durante su depósito. Por ejemplo litofacies de calizas oolíticas, areniscas glauconíticas, etc

criterios del establecimiento de litofacies:Contenido en un componente.Espesor de un componente litológico.Relación entre dos, tres, o cuatro componentes.

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Factores genéticos que condicionan el cambio de litofacies:-Subsidencia de la cuenca y su relación con la velocidad de sedimentación.-Factores climáticos, que controlan la cantidad y calidad de los aportes a una cuenca.-Factores ambientales, en los que se incluyen los que regulan la distribución de los aportes, dentro de una cuenca.

BIOFACIES.La biofacie, es el complementario y se refiere a los aspectos paleontológicos y a las condiciones biológicas presentes durante su depósito. Ejemplo: facies de gasterópodos, facies de carófitas, etc.

FACIES SÍSMICASEl término facies sísmicas, se utiliza para denominar al conjunto de propiedades observables en un perfil sísmico para un estrato o conjunto de estratos. Las propiedades son: configuración, amplitud, frecuencia, continuidad, velocidad de intervalo, etc. y permite diferenciar tipos de materiales y geometría de las superficies de estratificación.El volumen ocupado de los materiales de una misma facie sísmica es denominado unidad litosísmica.

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CHRONOSTRATIGRAPHY

The study of the ages of strata. The comparison, or correlation, of

separated strata can include study of their relative or absolute ages

ABSOLUTE AGE The measurement of AGE IN YEARS. The determination of the absolute age of rocks, minerals and fossils, in years before the present, is the basis for the field of geochronology. The measurement of the decay of radioactive isotopes, especially uranium, strontium, rubidium, argon and carbon, has allowed geologists to more precisely determine the age of rock formations. Tree rings and seasonal sedimentary deposits called VARVES can be counted to determine absolute age. Although the term implies otherwise, "absolute" ages typically have some amount of potential error and are inexact. Relative age, in contrast, is the determination of whether a given material is younger or older than other surrounding material on the basis of stratigraphic and structural relationships, such as superposition, or by interpretation of fossil content.

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LITHOSTRATIGRAPHYThe study and correlation of strata to elucidate Earth history on the basis of their lithology, or the nature of the well log response, mineral content, grain size, texture and color of rocks

BIOSTRATIGRAPHYThe application of plant and animal fossils to date and correlate strata in order to elucidate Earth history, combining the principles of paleontology and stratigraphy. In the petroleum industry, biostratigraphy often denotes the use of terrestrial (pollen and spores) and marine (diatoms, foraminifera, nannofossils) microfossils to determine the absolute or relative age and depositional environment of a particular formation, source rock or reservoir of interest

Formation The fundamental unit of lithostratigraphy. A body of rock that is sufficiently distinctive and continuous that it can be mapped. In stratigraphy, a formation is a body of strata of predominantly one type or combination of types; multiple formations form groups, and subdivisions of formations are members

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GEOCHRONOLOGY The study of the relative or absolute age of rocks, minerals and fossils. Absolute age is the measurement of age in years, but "absolute" ages typically have some amount of error and are inexact. Relative age, in contrast, is the approximate age of rocks, fossils or minerals made by determining the age of the material relative to other surrounding material.

ANGULAR UNCONFORMITYA surface that separates younger strata from eroded, dipping, older strata and represents a gap in the geologic record

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Angular conformityAngular conformity: younger sediments rest : younger sediments rest upon the eroded surface of tilted or folded older upon the eroded surface of tilted or folded older rocks.rocks.

DisconformityDisconformity:: contact between younger and contact between younger and older beds is marked by a visible, irregular or older beds is marked by a visible, irregular or uneven erosional surface.uneven erosional surface.  

ParaconformityParaconformity:: beds above and below the beds above and below the unconformity are parallel and no erosional unconformity are parallel and no erosional surface is evident; but can be recognized based surface is evident; but can be recognized based on the gap in the rock record.on the gap in the rock record.

NonconformityNonconformity: develops between : develops between sedimentary rock and older igneous or sedimentary rock and older igneous or metamorphic rock that has been exposed to metamorphic rock that has been exposed to erosion.erosion.

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ESTRATIGRAFÍA

TECTÓNICA DE PLACAS

REGIONAL

CAMPO

YACIMIENTO

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TECTONICA DE

PLACAS

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ESTRATIGRAFÍA A

NIVEL DE REGIONAL

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ESTRATIGRAFÍA A NIVEL DE REGIONAL

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Jurassic stratigraphic zonation

Up

per

Jura

ssic

jst6a

jst1

jst10

jst11

jst12

jst2

jst3

jst4a

jst5b

JST

jst6b

jst7a

jst7b

jst8

jst9

JSK

jsk1ajsk1b

jsk2

jsk3jsk4

jsk5

jsk6ajsk6b

JSOX

jsox1

jsox2

StratigraphicLayer

Western AtlasCunduacan -

Oxiacaque Study

jst4b

jst5a

JST1

JST2

JST3

JST4

JsKmm

JsOxf

JST5

JsCall

Mid

dle

Ju

rassic JSCAL

jscal1

jscal2

jscal3

jscal4

StratigraphicLayer

Western AtlasCunduacan -

Oxiacaque Study

Schlumberger H-RT

BermudezComplex

Integrated StudyStratigraphic

Layer

Schlumberger H-RT

BermudezComplex

Integrated StudyStratigraphic

Layer

17 Cretaceous stratigraphic zonation

Up

per

Cre

taceou

sM

idd

le C

reta

ceou

sLow

er

Cre

taceou

s

KS2.5

KS 0

KS 1.5

KS 3

KS 5

KS 1

KS 2

KM

KI3

KI4

KI2

KI1

KI2.5

KI5

KM

KI

KImd

KIls

km1

km2

km3km4

km5km6

km7

km8km9

KI

ki2

KM

ki1

StratigraphicLayer

Western AtlasCunduacan -

Oxiacaque Study

KSdf4

KSdwf4

KS3

KSpt3

KSdwf3

KS2

KSst2

KSdwf2

KS1KSst1

KSdwf1

Intera Samaria -Iride Study

KS4

StratigraphicLayer

KSpt1

KS

ks1a

ks1b

ks2

ks2aks2b

ks2c

ks2d

ks2e

ks3

ks4ks4a

ks1

KS

ks4b

Schlumberger H-RT

BermudezComplex

Integrated StudyStratigraphic

Layer

KIcd

18 Log character observed in stratigraphic zones

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Jurassic Tithonian talus breccia lithofacies. A) Talus debris flow bed about 1.5 m thick encased in laminated marl. B) FMI showing stacked cycles of laminated marl interbedded with talus debris packstones. C) Depositional model for debris flow beds encased in basinal limestone facies (Cook et al., 1972)

A

Laminated marl

Talus debris

Laminated marl

Laminatedmarl

CB

Laminatedmarl

Talus debris

Talus debris

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Lower Cretaceous talus breccia lithofacies. A) Talus debris flow breccia composed of lithoclast packstone. B) Talus breccia of lithoclast grainstone. Clast supported breccia of dolomitized mudstone clasts cemented with crystalline dolomite. C) Talus breccia of lithoclast packstone. Mudstone lithoclasts in a laminated marl matrix. D) Talus breccia of lithoclast wackestone. Mudstone clasts are suspended in a micrite matrix.

Cunduacan-41; 4301 m Cunduacan-41; 4205 mCunduacan-14; 4850-4856 m

Talus debris flow

Packstone breccia

A

CB D

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Grid of stratigraphic and structural cross sections included in study to document the structural and stratigraphic framework.

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Sección Litoestratigráfica con base en registros de pozo

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Sección Litoestratigráfica A-A´

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CONTROLES SOBRE EL DESARROLLO DE LA SECUENCIA

Eustacia

Subsidencia-/Levantamiento

Acomodo

Nivel del Mar relativo

Frecuencia de los Cambios en el nivel del mar

Suministro de sedimento

Nivel Base

Particionamiento Volumétrico

Diferenciación de Facies

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Retrogradation

The movement of coastline land-ward in response to a transgression.  This can occur during a sea-

level rise with low sediment flux.  Retrogradational stacking patterns of parasequences refer to

patterns in which facies become progressively more distal when traced upward vertically

El movimiento de la línea de la costa hacia tierra adentro en respuesta a una transgresión. Esto

puede ocurrir durante una subida del nivel del mar con flujo bajo del sedimento. Retrogradational

que apila patrones de parasequences refiere a los patrones en los cuales las facies llegan a ser

progresivamente más distal cuando están remontadas hacia arriba verticalmente

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AggradationVertical build up of a sedimentary sequence.  Usually occurs when there is a relative rise in sea level produced by subsidence and/or eustatic sea-level rise, and the rate of sediment influx is sufficient to maintain the depositional surface at or near sea level (i.e. carbonate keep-up in a HST [highstand Systems Tract] or clastic HST).  Occurs when sediment flux = rate of sea-level rise.  Produces Aggradational stacking patterns in parasequences when the patterns of facies at the top of each parasequence are essentially the same

Acumulación vertical de una secuencia sedimentaria. Ocurre generalmente cuando hay una subida relativa del nivel del mar producido por el hundimiento y/o subida eustatic del nivel del mar, y el índice de la afluencia del sedimento es suficiente mantener la superficie deposicional en o cerca del nivel del mar (es decir el carbonato guarda -para arriba en un HST [ zona de los sistemas del highstand ] o HST clástico). Ocurre cuando flujo del sedimento = índice de la subida del nivel del mar. Produce Aggradational que apila patrones en parasequences cuando los patrones de facies en la tapa de cada parasequence son esencialmente iguales

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ProgradationLateral outbuilding, or progradation, of strata in a sea-ward direction. Progradation can occur as a result of a sea-level rise accompanied by a high sediment flux (causing a regression).  This latter usually occurs during the late

stages of the development of a Highstand Systems Tract and/or an Falling Stage Systems Tract. A Progradational stacking pattern of parasequences refers to the pattern in which facies at the top of each

parasequence becomes progressively more proximal Dependencia lateral, o progradation, de estratos en una dirección de la mar-sala. Progradation puede ocurrir como resultado de una subida del nivel del mar acompañada por un alto flujo del

sedimento (que causa una regresión). Este último ocurre generalmente durante las últimas etapas del desarrollo de una zona de los sistemas de Highstand y/o de una zona de los sistemas de la

etapa que cae. Un Progradational que apila el patrón de parasequences refiere al patrón en el cual la facies en la tapa de cada parasequence llega a ser progresivamente más próxima

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EJERCICIOS

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