How r u doin’ folks,
Here we wanna share about a treacherous vernacular between “sequence” and parasequence”. First when we review method stratigraphy concepts created by Posamentier, Summerhayes and Haq, we got a indicate that method is aloft method lees package than parasequence. Sequence (in Posamentier et al) is resolved as sedimentary package restrained by unconformity subsequent and above or a correlative consent seaward. Posamentier et al (1989) here was explaining that method is a sedimentary package that shows a compliant period of a sedimentation. So, it was resolved that a method is a compliant array of a lees deposited from lowest sea turn condition to subsequent lowest sea turn condition in a basin.
Parasequence, what is a parasequence?. Parasequence is a compliant period of a lees restrained by a deepening eventuality of a such basin. parasequence mostly stacks and amalgamated in one relations sea turn condition. For example, in condition of relations sea turn delayed rise/stillstands we could find a progradation of mixed parasequences, in condition of relations sea turn arise we could find retrograded parasequences. Then, in a condition of relations sea turn keeps in change with rate of lees supply we could find agraded parasequences.
What is a focus of these vernacular (sequence and parasequence)?
If we can find a subaerial unconformity (sequence boundary, shaped on Posamentier et al ‘s concept) and traced that pen around a given basin, afterwards we will be means to minimalize a luck of misscorrelation around a basin. If we speak about method it’s meant that we speak in dish scale. For sharping a fortitude of association than we grouped those lees interlude in one method to some parasequences. If we’re articulate in parasequence it’s meant we are articulate in fountainhead scale. Many fountainhead zones today in such dish operated by PSC Companies are divided in some parasequences. In a book created in 1989, Posamentier et al also make a split between method and parasequence shaped on a lees density and time comsuming for deposition.
In Catunenau (2003), method and parasequence is grouped in extremelly opposite model. Sequence (catuneanu, 2003) is a sedimentary package restrained by method operation (it could subaerial unconformity in depositional method indication or limit flooding aspect in genetic method indication or limit retrogression aspect in trangressive-regressive method model), and parasequence in catuneanu is categorized as a litostartigraphy concepts.
Catunenau (2003) is perplexing to be design and revoke a treacherous of method stratigraphy terminology, though it make method stratigraphy itself some-more treacherous for a student.
Then if we review a paper created by Nummedal et al (1995) afterwards we could exhibit a myth between parasequence and sequence. Sometimes we dont determine with a concepts of Posamnetier et al, means a split of method and parasequence shaped on a density operation and time comsuming, though it doesnt meant that we totally dont determine with a POsamnetier’s concepts, it only about a density and time comsuming.
In Nummedal (1993), we could find that parasequence and method are extremelly opposite if noticed tray a sea turn relations fluctuation. Nummedal et al (1993) resolved that a parasequence is a sedimentary package restrained by H2O deepening (final trangressive surface) and method is a sedimentary package restrained by H2O shallowing (regressive aspect of erosion). Nummedal et al (1993) pronounced that parasequence and method can have same time comsuming and same in thickness. So, a split of method and parasequence shaped on time immoderate and density can't be widely used. For some box those parameters are applicable, though not unequivocally in whole basins.
Parasequence is deposited in a such condition of one full cycle of relations sea live arise though descending situation. So, a parasequence is shaped from a top relations sea turn to a subsequent top relations sea turn though descending limb. For that situation, a parasequence should have normal backward sediement and tarangressive partial sediment. Normal backward sediemnt and trangressive strata is distant by initial trangressive surface.
Sequence (Nummedal, 1993) is deposited in such condition of one full cycle of relations lowest sea turn to subsequent lowest sea level. So a cycle in method is from low turn – rise-then low turn again. Parasequence has opposite scheme, that is high turn – arise (but normaly regressive)-high turn again.
An accurate indication for wrapping sedimentary rocks from dish scale to fountainhead scale is a pivotal succes for grabbing opportunities in building and exploring oil/gas field.
Sorry if i didnt upload design and animation for deliberating this topic, it only was caused by we didnt have those things yet. we entice all my friends to plead this subject while we am perplexing to revise this display to be some-more excellent.
