What is a depositional sequence?

A depositional sequence is defined as a relatively conformable succession of genetically related strata bounded by subaerial unconformities or their correlative conformities.

What is the sedimentary sequence?

Sedimentary sequences are layers of rock which are derived from weathered rocks, biogenic (= of living organisms) activity, or precipitation from solution.

What is transgressive sequence?

A transgression occurs when the rate of sea level rise landward exceeds the rate of sediment input and causes an increase in accommodation, initiating the development of a transgressive surface over which the trangressive sediments of the transgressive systems tract onlap and retrograde.

What is seismic sequence analysis?

The objective of seismic sequence analysis is to identify depositional sequences and systems tracts on seismic sections by interpreting the location of their boundaries. Boundaries are manifested as discontinuities in seismic sections and are located mainly by finding reflection terminations.

What is sequence boundary?

Sequence boundary (SB)

A sequence boundary is a surface formed by subaerial exposure that occupies a sequence-bounding position between an underlying RST and an overlying TST.

What is a horizontal sedimentary sequence?

Principle of Superposition, states that in an undisturbed sedimentary sequence, the older beds are on the bottom, and the younger beds are on the top. Principle of Original Horizontality, states that sediments are deposited in flat, horizontal layers.

Why is sequence stratigraphy important?

Sequence stratigraphy can be used to develop more accurate surfaces for mapping and correlating facies; predict reservoir, source and sealing facies; identify stratigraphic traps; and project reservoir trends into areas with limited data.

Why is sequence stratigraphy important for petroleum?

Sequence stratigraphic techniques provide (1) a more effective method for evaluating reservoir system continuity and trend directions and (2) improved methods for predicting reservoir system, source, and sealing facies away from well control.

What is an archaeological sequence?

Archaeological stratification or sequence is the dynamic superimposition of single units of stratigraphy, or contexts. Contexts are single events or actions that leave discrete, detectable traces in the archaeological sequence or stratigraphy.

Who invented sequence stratigraphy?

Peter Vail

Sequence stratigraphy is a recent methodology for stratigraphic interpretation, pioneered by Peter Vail in the mid 70’s (Vail et al 1977), that explains the complex geometries that sediments acquire as they fill accommodation in response to changes in rates of sedimentation, tectonic and eustatic movement.

What is a facies in geology?

1. n. [Geology] The overall characteristics of a rock unit that reflect its origin and differentiate the unit from others around it. Mineralogy and sedimentary source, fossil content, sedimentary structures and texture distinguish one facies from another. See: depositional environment, lithofacies.

What is TST in sequence stratigraphy?

A transgressive systems tract (TST) is bounded by maximum regressive surface at the base and maximum flooding surface at the top. This systems tracts forms when the rate of sedimentation is outpaced by the rate of sea level rise in the sea level curves.

What are Sloss sequences?

DEFINITION: The Sauk Sequence (Sloss and others, 1949) comprises those strata that overlie an interregional conformity cut on late Pre- cambrian and older rocks and underlie an Page 4 96 L. L. SLOSS—SEQUENCES IN CRATONIC INTERIOR OF NORTH AMERICA interregional unconformity at the base of the succeeding Tippecanoe …

What cratonic sequence is recognized in North America that dominates Cambrian time?

There have been six cratonic sequences since the beginning of the Cambrian Period. For North America, from oldest to youngest, they are the Sauk, Tippecanoe, Kaskaskia, Absaroka, Zuñi, and the Tejas.

What is regression geology?

Regression: the oceanward migration of the shoreline (i.e., draining of flooded land) During a transgression the sequence of rocks will show an onlap sequence (the facies will become deeper-water environments as you move up through the sediments).

What is the order of Paleozoic sequences from oldest to youngest?

The Paleozoic era is divided into six periods. From oldest to youngest, these are the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian.

What is the order of Paleozoic sequences from oldest to youngest quizlet?

The four Paleozoic transgressive sequences are in order from oldest to youngest are Sauk, Tippecanoe, Kaskaskia, and Zuni. During a transgressive sequence, sedimentary facies migrate oceanward.

What is the significance of the black shales of the Kaskaskia sequence?

Beginning in the late Devonian, black shales begin to dominate in the rocks, composed of detritus eroded from the uplifted Acadian highlands to the west; they also indicate widespread anoxic conditions across the sea floor.

What happened during the Sauk sequence?

The sauk sequence was terminated abruptly about 490 million years ago when sea level suddenly dropped (on geological timescales, taking a few million years), leading to widespread erosion and the formation of a worldwide unconformity surface on top of the sauk sequence.

When give the periods and the years did the Sauk sea cover much of the United States?

It dates from the late Proterozoic through the early Ordovician periods, though the marine transgression did not begin in earnest until the middle Cambrian. At its peak, most of North America was covered by the shallow Sauk Sea, save for parts of the Canadian Shield and the islands of the Transcontinental Arch.

What was the Sauk transgression?

The Sauk transgression was one of the most dramatic global marine transgressions in Earth history. It is recorded by deposition of predominantly Cambrian non-marine to shallow marine sheet sandstones unconformably above basement rocks far into the interiors of many continents.

What caused the Sauk sea transgression?

– the continents have been flooded periodically throughout the Phanerozoic. Transgressions yield thick sequences (Sauk, Tippecanoe, etc.) of shallow marine sediments on the craton and probably result from periods of fast seafloor spreading.

What is a craton in geology?

craton, the stable interior portion of a continent characteristically composed of ancient crystalline basement rock. The term craton is used to distinguish such regions from mobile geosynclinal troughs, which are linear belts of sediment accumulations subject to subsidence (i.e., downwarping).

What age is the Sauk sequence?

about 650 to 460 million years ago

recognized of these are the Sauk Sequence (Late Precambrian to mid-Ordovician; about 650 to 460 million years ago), the Tippecanoe Sequence (mid-Ordovician to Early Devonian; about 460 to 400 million years ago), the Kaskaskia Sequence (Early Devonian to mid-Carboniferous; about 408 to 320 million years ago), and the …

What sequence of rocks indicates the occurrence of the Sauk transgression?

4. Extensive sequences of Cambrian marine sediments (sandstone, shale & fossil-bearing limestone) indicate that the continents were at times flooded by great shallow seaways. North America was almost completely drowned in Late Cambrian time by what came to be known as the Sauk transgression. 5.

When did the Tippecanoe sequence end?

The massive evaporite deposits of the Michigan Basin were created during this period. The Tippecanoe sequence ended with a regression in the early Devonian, to be followed later by the Kaskaskia sequence.

What is a transgressive regressive sequence that is bounded by an unconformity called?

Cratonic sequence: large-scale (greater than supergroup) lithostratigraphic unit representing a major transgressive-regressive cycle bounded by craton-wide unconformities. • Sedimentary rock record of North America is divided into six cratonic sequences. The study of cratonic sequences is called sequence stratigraphy.