What were the two major cratonic sequences in the late Paleozoic?
Explain and define the major cratonic sequences—Kaskaskia, Absaroka—of North America during Late Paleozoic.
Which of the following cratonic sequences is the oldest?
These sequences were given names. The oldest was the Sauk, followed by the Tippecanoe, Kaskaskia, Absaroka, Zuni, and Tejas.
Why is the Sauk sequence significant to geological history?
The Sauk sequence was the earliest of the six cratonic sequences that have occurred during the Phanerozoic in North America. 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.
How long did the Sauk sequence last?
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 is a Sloss sequence?
A cratonic sequence is a very large-scale lithostratographic sequence in the rock record that represents a complete cycle of marine transgression and regression on a craton (block of continental crust) over geologic time. Cratonic sequences were first proposed by Laurence L. Sloss in 1963.
What is the youngest last period in the Paleozoic?
The major divisions of the Paleozoic Era, from oldest to youngest, are the Cambrian (541 million to 485.4 million years ago), Ordovician (485.4 million to 443.8 million years ago), Silurian (443.8 million to 419.2 million years ago), Devonian (419.2 million to 358.9 million years ago), Carboniferous (358.9 million to …
What causes cratonic sequence?
The most likely causes of these cycles is change in mid-ocean ridge volume, which is related to seafloor spreading rates. This elevated lithosphere displaces seawater onto the continents; conversely, when spreading rates decline, the ridges subside, and the seas drain from the cratons.
Who is the father of stratigraphy?
geologist William Smith
The man credited as the “father of stratigraphy,” however, was the English engineer and geologist William Smith (1769-1839). In 1815 Smith produced the first modern geologic map, showing rock strata in England and Wales.
What is geologic time scale?
Geologic time, the extensive interval of time occupied by the geologic history of Earth. The geologic time scale is the “calendar” for events in Earth history. It subdivides all time into named units of abstract time called—in descending order of duration—eons, eras, periods, epochs, and ages.
What kind of paleo environment is characteristic of the Tippecanoe sequence?
a) An angular unconformity. (ch. 20) What kind of paleo-environment is characteristic of the Tippecanoe sequence? a) Reef systems with abundant carbonates.
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.
What cratonic sequence began in the Cambrian?
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.
Which is the best description of a cratonic sequence?
A cratonic sequence is a very large-scale lithostratographic sequence that covers a complete marine transgressive-regressive cycle across a craton. They are also known as “megasequences”, “stratigraphic sequences”, “sloss sequence” or simply “sequences.”.
How did Lawrence Sloss come up with the cratonic sequence?
Cratonic sequences were first proposed by Lawrence Sloss in 1963; each one represents a time when epeiric seas deposited sediments across the craton, while the upper and lower edges of the sequence are bounded by craton-wide unconformities eroded when the seas receded.
Where are the Sloss sequences in North America?
Sedimentary “Sloss” Sequences of North America. In the Mid-Atlantic region, the Sauk, Tippecanoe, and Kaskaskia are well exposed. White and yellow areas represent major marine transgressions onto the craton while black areas represent major unconformities (sequence boundaries).
Why are there so many cratonic cycles in the ocean?
These sequences may in part represent eustatic or global change in sea level; however, when the proper names are used they usually refer to the North American continent. The most likely causes of these cycles is change in mid-ocean ridge volume, which is related to spreading rates.