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Amy Lombari Zoe Gentes Andew Infante Jennifer Sullivan Dennis Titterton.

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Presentation on theme: "Amy Lombari Zoe Gentes Andew Infante Jennifer Sullivan Dennis Titterton."— Presentation transcript:

1 Amy Lombari Zoe Gentes Andew Infante Jennifer Sullivan Dennis Titterton

2 Pangaea  The breakup of Pangaea is estimated to have occurred around 200 million years ago during the Mesozoic era (early Jurassic period) (Tarbuck, 2002)  Rifting started in the late Triassic period and continued to completely separate Pangaea to form two separate masses known as Laurasia and Gondwana  Basaltic oceanic crust forms between continents that are separating

3 Pangaea continued  The breakup of Pangaea took place over four stages  The first stage is relevant to our subject and the Connecticut rift valley:  The rifting between Laurasia and Gondwana during the Late Triassic. By the end of the Triassic, the expanding Atlantic Ocean separated North America from Africa. (Wicander and Munroe, 2002)

4 Region of Interest  Connecticut (CT) rift valley  Region of continent- continent rifting  Type of sediments  Volcanism due to rifting  Amongst many other areas, a large record of this rift can be found in the Central Valley area of Connecticut.  The CT valley is a down faulted crustal segment with dimensions of 5 to 20 by 105 miles.  It is split into 2 basins, each with their own sedimentary and volcanic records

5 Rift Valleys  The central valley of CT is one of the areas affected by the continental rift between the North American craton and the African craton Continental Rifting: ○ Convection and mantle plumes are two mechanisms involved in the cause of the continental rift ○ Pangaea acted as an insulation for the mantle plume which resulted in a significant change in convection beneath the supercontinent

6 Basic rift model  Divergent plate boundary  Progressive formation of a rift valley through extension of the lithosphere and continental crust  The crust responds by brittle fracture.  Early rift sediments are downfaulted into the developing rift.  Erosion takes place on the sides of the rift valley

7 Sediments  The Harford basin is one of several rift basins in the eastern United States that formed during the breakup of Pangaea.  Over millions of years, the Hartford basin accumulated clastic sediments as well as basaltic lava  Early Devonian rocks consist of marine clastic deposits with subordinate carbonates, lava flows and terrestrial deposits  These sediments are located here due to the once lacustrian environment

8 Paleoenvironments  Plant fossils and the presence of evaporites provide evidence for a climate that repeatedly altered between humid and arid (Prothero and Dott, 2002)  The basin contains imprints of leaves, bark and wood that tells us that in Mesozoic times, Connecticut had a tropical climate Plants found included; conifers, horsetails, giant club mosses and cycads

9 Volcanisim  In a Rift Valley volcanoes are not as explosive  Mafic lava  High viscosity, high volatile content in felsic lava makes the volcano more explosive  Dikes and sills are very common in the Central Valley of CT. They were formed when cracks in the lithosphere/crust were filled with lava from beneath the rift.

10 Volcanism continued  We can use paleomagnetic stratigraphy to determine that there were different volcanic events that occurred in the late Triassic period (Tremblay and Pinet, 2005)  Basalt is found in the rift valley because of volcanism  As lava flowed into lakes it formed pillow basalts esozoic/connecticut.htm

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12 References  Alain Tremblay and Nicholas Pinet, 2005, Diachronous supracrustal extension in an intraplate setting and the origin of the Connecticut Valley–Gaspé and Merrimack troughs, northern Appalachians. Geological Magazine, 142, pp 7-22  Donald R.Prothero and Robert H. Dott, 2002, Evolution of the Earth, Edition 6, McGraw Hill, New York, New York, p. 384  Tarbuck, Edward D., Frederick K. Lutgens, and Tasa Dennis, 2002 Earth: An Introduction to Physical Geology. 7th ed. Upper Saddle River, NJ: Prentice Hall  Wicander, Reed; Monroe, James S., 2000, Historical Geology: Evolution of Earth and Life Through Time, 3rd ed., Brooks/Cole, pp

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