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Lecture 5

ISCI 2A18 Lecture Notes - Lecture 5: Cenote, Megabat, Smart GuyPremium

5 pages67 viewsFall 2014

Department
Integrated Science
Course Code
ISCI 2A18
Professor
Carolyn Eyles
Lecture
5

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HotE Guest Lectures
Kristinn Bardarbunga Eruption
There is a volcanic eruption that is taking place in Iceland as we speak! It started on August
31st, and we don’t know how long it will last. The eruption occurred in Bardarbunga,
Iceland. It is a fissure eruption that produced more lava in the first five hours than the last
big one in the entire eruption. The lava field that was created from this eruption is the largest
lava field since some eruption in the 1700s.
Volcanoes are usually found along plate margins. The volcanic activity from the past 10,000
years largely misses the eruptions along the mid-ocean ridges because they are hard to detect.
If a volcano is not along a plate margin, it is likely on a hot spot.
Iceland is a hot spot that coincides with a constructive plate margin. Low density magma of
the mantle plume lifts the mid-ocean ridge out of the ocean (lifting the island above sea
level). This is quite unique. The plate margins go through the island. The west part of
Iceland is part of the North American plate, while the east part is a part of the Euro-Asian
plate. The plates spread apart along this axis by 2cm/yr.
The fire heart of Iceland lifts it out of the ocean.
One eruption every 3 years occurs in Iceland during high activity and once every 5 years
during low activity. The peaks and lows are separated by periods of about 200 years. We are
currently reaching the peak activity now (increased activity in the coming 100 years).
Additionally, the glaciers are thinning , removing the massive mounds of ice on the land. The
crust undergoes isostatic rebound, which allow magma to push up to the surface. The
eruptions are usually effusive basaltic fissure eruptions (Icelandic, Stromboliam, and
Sutrseyian eruptions). There are mixed and explosive eruptions (Pelian and Volcanian),
which are associated with centrla volcanoes (felsic or intermediate magma). True Hawaiian
eruptions were common during the early Holocene. FINISH
Development of magma from mafic to felsic - main processes. The magma sits there for a
long time, at which point it starts cooling. There is partial melting of neighbouring rock (low
melting point compounds). At the same time, there is partial crystallization of magma
FINISH. This is how you get felsic lavas in Iceland!
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When North America (from Texas to Yukon) was Under the Sea
Tuesday, 18 November, 2014
Janok P. Bhattacharya
The cliffs that are the structural base for Niagara Falls used to be completely submerged.
Niagara FAlls falls over marine limestones, and other thigns.
During the Permian, all of the contienets were close together. This was an Icehouse period
that had an enormous Himalayan style mountain belt (appalachians) record continent-
continent collision.
By the Early Cretaceous, we have the Pangaean Breakup and a Greenhouse period.
In the late Cretaceous, there are extensive shallow seas (Western Inland Basin). The entire
Cretaceous is known as a global greenhouse because it is thought that there were no glaciers
during this time. There were continental glaciers. Janok has evidence with his Western friend
that there were more glaciers.
The Pleistocene involved major ice sheets covering North America and Europe. It was a true
icehouse.
In the modern day, there is a retreat of ice sheets. Interstadial within a global “icehouse”.
The ice sheets will return? Will global warming mitigate global cooling?
Fossilized eolian dunes are indicative of ancient deserts. Mirgation of eolian dunes produces
meters of thick cross-stratification. Additionally, there are footprints of Permian vertebrates
living within the environment, so it must have been out of water. These were Jurassic
deserts.
Janok works in western Utah because it is a desert. He looks at the Ferron Sandstone
Outcrop. There are superb exposures near Capitol Reef, Utah. A reef is just a fold in the
landscape that makes it difficult to navigate. The reef was the barrier to the Mormon
travelers to getting any further west in Utah.
Complex bedding geometry is used to decipher facies architecture. Results applied to
outcrop reservoir characterization of subsurface oil and gas fields. Data can be used to
provide dimensions of sand bodies within the rock.
Laterally migrating cars overlie floodplain mudstones contained within larger erosional
features. This is in the exhumed Ferron Paleo-Valley.
You also find dinosaur remnants! Janok found a sacral vertebrate of a small Ornithopod.
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