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How were the two studies similar in their efforts to test the SWEAT hypothesis, and how did they differ?

How were the two studies similar in their efforts to test the SWEAT hypothesis, and how did they differ?

Applications and Investigations in Earth Science (9th Edition)
Applications and Investigations in Earth Science (9th Edition)
9th Edition
ISBN:9780134746241
Author:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa
Publisher:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa
Chapter1: The Study Of Minerals
Section: Chapter Questions
Problem 1LR
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As a field researcher during the late 1980's and early 1990's, Borg authored papers on the SWEAT hypothesis. The boulder find came by serendipity while the researchers were picking though rubble carried through the Transantarctic Mountains by ice streams-rivers of ice-that flow at literally a glacial pace from East Antarctica. Goodge and his team were searching for rocks that might provide keys to the composition of the underlying continent crust of Antarctica, which in most places buried under almost two miles of ice. "We were picking up boulders in the moraines that looked interesting," Goodge said. "It was basically just a hodge-podge of material." One rock in particular, small enough to heft in one hand, found atop the Nimrod Glacier, was later determined to be a very specific form of granite with, as Goodge describes it, "a particular type of coarse-grained texture." Subsequent chemical and isotopic tests conducted in laboratories in the United States revealed that the boulder had a chemistry "very similar to a unique belt of igneous rocks in North America" that stretches from what is now California eastward through New Mexico to Kansas, Illinois and eventually through New Brunswick and Newfoundland in Canada. That belt of rocks is known to have been a part of what is called Laurentia, which was a component of the supercontinent of Rodinia. "There is a long, linear belt of these igneous rocks that stretches across Laurentia. But 'bang' it stops, right there at the (western) margin where we knew that something rifted away" from what is now the West Coast of the United States," Goodge said. "It just ends right where that ancient rift margin is," Goodge said. "And these rocks are basically not found in any other part of the world." That it should turn up on a glacier high up in the mountains of Antarctica is strong evidence in support of the SWEAT model that parts of North America continue into part of the frozen continent at the bottom of the Earth. "There's no other explanation for how it got where we found it," Goodge said. "It was bull-dozed over from that interior region of Antarctica." The find itself is compelling to geologists, Goodge noted, because little other physical evidences exists to allow them directly to put together the jigsaw puzzle of the long-disappeared Rodinia But because the supercontinent existed at a key time in the development of multi-cellular life on Earth, it also helps provide a geological context in which this massive biotic change took place. "During the Cambrian explosion about million years ago we started seeing this huge expansion in the diversity of life forms," Goodge said. "This was also a time when the Earth was undergoing tremendous geologic changes." He added that "something helped trigger that big radiation in life."
Transcribed Image Text:As a field researcher during the late 1980's and early 1990's, Borg authored papers on the SWEAT hypothesis. The boulder find came by serendipity while the researchers were picking though rubble carried through the Transantarctic Mountains by ice streams-rivers of ice-that flow at literally a glacial pace from East Antarctica. Goodge and his team were searching for rocks that might provide keys to the composition of the underlying continent crust of Antarctica, which in most places buried under almost two miles of ice. "We were picking up boulders in the moraines that looked interesting," Goodge said. "It was basically just a hodge-podge of material." One rock in particular, small enough to heft in one hand, found atop the Nimrod Glacier, was later determined to be a very specific form of granite with, as Goodge describes it, "a particular type of coarse-grained texture." Subsequent chemical and isotopic tests conducted in laboratories in the United States revealed that the boulder had a chemistry "very similar to a unique belt of igneous rocks in North America" that stretches from what is now California eastward through New Mexico to Kansas, Illinois and eventually through New Brunswick and Newfoundland in Canada. That belt of rocks is known to have been a part of what is called Laurentia, which was a component of the supercontinent of Rodinia. "There is a long, linear belt of these igneous rocks that stretches across Laurentia. But 'bang' it stops, right there at the (western) margin where we knew that something rifted away" from what is now the West Coast of the United States," Goodge said. "It just ends right where that ancient rift margin is," Goodge said. "And these rocks are basically not found in any other part of the world." That it should turn up on a glacier high up in the mountains of Antarctica is strong evidence in support of the SWEAT model that parts of North America continue into part of the frozen continent at the bottom of the Earth. "There's no other explanation for how it got where we found it," Goodge said. "It was bull-dozed over from that interior region of Antarctica." The find itself is compelling to geologists, Goodge noted, because little other physical evidences exists to allow them directly to put together the jigsaw puzzle of the long-disappeared Rodinia But because the supercontinent existed at a key time in the development of multi-cellular life on Earth, it also helps provide a geological context in which this massive biotic change took place. "During the Cambrian explosion about million years ago we started seeing this huge expansion in the diversity of life forms," Goodge said. "This was also a time when the Earth was undergoing tremendous geologic changes." He added that "something helped trigger that big radiation in life."
How were the two studies similar in their efforts to test the SWEAT hypothesis, and how did they differ?
Transcribed Image Text:How were the two studies similar in their efforts to test the SWEAT hypothesis, and how did they differ?
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