GLY3105C Topic 3

Transcontinental Arch

-Extension of the Canadian Shield consisting of a long belt of crytozoic rock from Lake Superior to Arizona. -Mountains (high elevation) -Stood above shallow Cambrian seas, only area above water during Sauk and Tippecanoe Sequence

St. Peter Sandstone

-Tippecanoe sequence - Mature, very pure quartz sandstone -sheet of sand in clear shallow water -Ordovician Formation

Sauk Sequence

Transgression, early ordovician, isolated continents in well connected sea, end of ordovician was cold (ice age) which led to regression. Baltica moved toward Laurentia.

In the middle Ordovician, simple true reefs appeared. (T/F)

True

Warming in the Cambrian relative to the paleoclimate in the Precambrian was followed by climate cooling and extinctions in the Ordovician

True

Turbidite

a graded bed of sediment built up at the base of a submarine slope and deposited by turbidity currents

How can an isopach map of the Cambrian be utilized to infer water depth over North America and its margins at the time of deposition?

...

Queenston Delta

A clastic wedge over current North America resulting from erosion of the highlands formed during the Taconic orogeny during late Ordovician.-Thickest in band from NY state to Quebec, Catskill mountain to Lake Heron

Clastic Wedge

An extensive accumulation of mostly detrital sedimentary rocks eroded from, and deposited adjacent to, an area of uplift, as in the Catskill Delta or Queenston Delta.

Discuss some major differences between sediments and sedimentary processes of the Archean versus the Cambrian-Ordovician.

Cambrian:-Pole in oceanic area, no land N or S of degrees of latitude Ordovician:- Portions of Gondwana moved to polar position (glaciated)-Iapetus Ocean seperated North America form Baltica and Gondwanaland (African portion)-Baltica began moving toward Laurentia , closing Iapetus and leading to Taconic Orogeny-North American and Laurentia were astride equator

The terminal Ordovician Extinction led to:

Compression of biogeographic zones toward the equator extinction of 100 families of invertebrates extinction of more tropical groups, due to climatic cooling ALL OF THESE OPTIONS

What are the sedimentary characteristics of the basal transgressive sandstone (Ordovician St. Peter Sandstone) of the Tippecanoe sequence? How did such a pure and widespread sand body form?

Fine-to-medium sized, well-rounded quartz grains with frosted surfaces. Formed as a sheet of sand in clear shallow water near the shore of Paleozoic Sea. - Mature, very pure quartz sandstone

Taconic Orogeny

First mountain building event of paleozoic Volcanic arcs formed off North America

_________ is a sequence of sedimentary rock layers that progress from deep-water and turbidity flow deposits to shallow water shales and sandstones. It is deposited when a deep basin forms rapidly on the continental side of a mountain building episode

Flysch

Ophiolite

Igneous rock consisting largely of serpentine, formed from submarine eruption of oceanic crustal and upper mantle material

Which type of map displays the thickness of strata in map view

Isopach

_______________ refers to sandstones, shales and conglomerates that form as terrestrial or shallow marine deposits in front of a rising mountain chains. These deposits accumulate in a foreland basin, especially on top of a flysch- like deposits. These deposits are typically the non-marine alluvial and fluvial sediments of lowlands, as compared to deep- water flysch sediments. Sedimentation stops when the orogeny stops or when the mountains have eroded flat.

Molasse

The erosion of sediment from the Sauk sequence during the Taconic Orogeny created a foreland basin that filled with sediment and is called the ___________ delta.

Queenston

Name in order from oldest to youngest the two transgressions that occurred in North America from the middle Cambrian to late Ordivician/ early Silurian

Sauk, Tippecanoe

Iapetus Ocean

Seperated Gondwana, Baltica, Siberia, Laurentia

Molasse

Terrestrial, shallow marine deposits

Tippecanoe Sequence

deeper than Sauk transgression, marked by St. Peter Sandstone, transcontinental arch remained above sea level

Isopach Map

displays thickness of strata in map view

The Cambrian and Ordovician Periods were a time of ________ _______ North America

relative stability for

A transgression is a _________ of sea level and a regression is a ______ of sea level

rising; falling

Flysch

sequence of layers that progress from deep-water and turbidity flow deposits to shallow water shales and sandstones.