A supercontinent, known as Pangea, was formed by the aggregation of all the world’s landmasses in the Late Triassic-Early Jurassic. This concept of a supercontinent was originally proposed by Alfred Wegener (Wegener, 1915). He suggested that all continents assembled into a single supercontinent, approximately 300 million years ago, and then according to the theory of plate tectonics, began to break apart 175 million years ago (Rogers et al., 2004) Immense geologic and geophysical evidence have been presented, by Wegener and others, to support this theory for the Late Triassic-Early Jurassic. However when analyzing the paleomagnetic data for the Late Paleozoic time, inconsistencies are present which suggest a very different Pangea construction. These inconsistencies are seen in Late Paleozoic paleomagnetic data apparent polar wander paths (APWPs) for Laurussia and Gondwana. To fit Wegner’s Pangea reconstruction, the APWPs suggest a substantial crustal overlap and shearing (Domeier et al., 2012). This paper looks to review proposed alternative reconstructions for Pangea, using paleomagnetic data as the quantifiable method for determining the supercontinent’s location.
Paleomagnetic data as evidence for Plate Tectonics
Paleomagnetism is the study of earth’s magnetic field as preserved in the magnetic orientation of certain minerals. For example, when igneous rocks are formed, during cooling, certain minerals align themselves with the earth’s magnetic field and
According to the theory of “Pangaea,” the world was once a single mega-continent that contained all the dry land about 225 million years ago. North America was shaped by the majestic Canadian Shield about 10 million years ago.
Studies of the age of molten rock in the ocean crust confirm the magnetic data. Molten rock contains radioactive isotopes used to calculate the time of the eruption. Rocks near the Mid- Atlantic Ridge, in addition to current like structures happened to be rather young, only some million years aged or a lesser amount (Trefil & Hazen, 2010). Rocks gathered one after another farthest from the range established them to be in turn older. Up to date evidence on charting the surfaces of oceans, maps of rock magnetism, and data on the age of rock indicate to countless expert that the span of the Atlantic Ocean for all intents and purposes is
Schulz’s article is split into five sections. The first section introduces the readers to Chris Goldfinger, a paleoseismologist at Oregon State University. Goldfinger was at a seismology conference in Kashiwa, Japan when the 2011 Tohoku
About 225 million years, all of the world’s land was contained in one supercontinent, named Pangea. This supercontinent would eventually separate itself into the continents that are known today, due to continuous movement of the earth’s tectonic plates, which led to major shifting and folding of the earth’s crust. This shifting formed many of the mountain ranges that exist today, such as the Appalachians and the Rocky Mountains. However, the time of Pangea’s separation into multiple continents and the time of the formation of the mountain ranges aren’t synonymous; for instance, the Appalachians were most likely formed before Pangea’s separation. About some 2 million years ago, a Great Ice Age befell the earth, which caused a
The Cretaceous Period had a similar climate to the Jurassic, warm. The geography, however, was changed a drastic amount from the previous period. The Earth had very high sea levels at this time due to the lack of polar ice caps. The supercontinents Laurasia and Gondwana were breaking apart into the continents that are the same in the present day. Although the continents were the same, they did not yet look exactly the same. The continents will be further shaped by volcanic activity and tectonic plate activity. The shaping of the modern era was under way.
200 million years ago a supercontinent called Gondwana existed. It was made up of South America, Africa, Australia, India, and Antarctica. Fossil evidence shows that certain species have lived in multiple places, but these places are far apart. This proves that they lived in one place, but were separated from their ancestors when the plates split, causing earthquakes. In addition,
During the early to middle Palaeozoic, the northwest orientation was the main deformation features in Australia and Northern Carnarvon Basin. In Northern Carnarvon Basin, several sub-basins and Plateaus are separated by northwest oriented faults and basement highs. Cape Range Fracture Zone (CRFZ) separates the west side of Exmouth Plateau, the Long Island Fault System separates the southern boundary of Barrow Sub-Basin and Sultan Nose uplift separates the Barrow from Dumpier Sub-Basin (DAIM, 1998). During middle Palaeozoic, basin started extending to northeast direction and deformation and structures orientation shifted from the Northwest to the Northeast trend. These northeast structural features were inherited to the deformation pattern throughout Mesozoic. Intermittent rifting of Australia
However, it was not until the second half of the 20th century that three major discoveries began to suggest how this might be possible. In 1948, a survey of the floor of the Atlantic Ocean revealed a continuous ridge running largely north to south. IT was around 1,000km wide and reaching heights of 2.5km. It was composed of volcanic rocks. Similar submarine mountain ranges were later found in the Pacific Ocean extending for over 5,000km. Magnetic surveys of the ocean floor in the 1950’s showed surprisingly regular patterns of palaeomagnetic striping about the ridges. When lavas erupt on the ocean floor, magnetic domains within iron-rich minerals in the lava are aligned with the magnetic field of the earth. This is fixed as the lava cools, and unless the rocks undergo major disturbance, they continue to record the earth’s polarity at the time of their cooling. However, as the earth’s polarity reverses around every 400,000 years, bands or stripes of normal and reverse polarity rocks are mirrored on either side of the mid-ocean ridges. This suggests that new rocks are being added equally on either side.
Questions were raised when rocks were found on the surface of the Earth that had manetization the did not corralate to the location that it was found. Also, Harry Hess suggested that the continents could have drifted and still were because the sea floor was moving much like a conveyor. (Bugielski, 1999).
The Permian Time frame was the last time of the Paleozoic Time. Enduring from 299 million to 251 million years back, it took after the Carboniferous Time frame and went before the Triassic Time frame. By the early Permian, the two-extraordinary mainland’s of the Paleozoic, Gondwana and Euramerica, had crashed to frame the supercontinent Pangaea. Pangaea was formed like a thickened letter "C." The best bend of the "C" comprised of landmasses that would later wind up present-day Europe and Asia.
The earth has been through a lot of changes throughout time. It used to be thought that the continents were locked in their positions and couldn’t move, but in 1915 Alfred Wagner came up with a theory about continental drift (Tarbuck and Lutgens, 2015). While unsure of the process that happened at the time, Wagner also came up with the idea that all the continents in existence today were once all connected as one giant continent known as Pangea. This idea is supported by the findings of similar rocks or fossils in multiple locations separated by large water bodies. Thanks to more tools and funding, the oceanic ridge system was found and by 1968, the theory of plate tectonics was introduced (Tarbuck and Lutgens, 2015). This theory
The last supercontinent was Pangaea and it formed around 300 million years ago. Blackstone's rocks, safely floating and rotating on Laurentia, as it headed towards a collision with what would become Africa. Pangaea lasted 100 million
The Jurassic Period was the second half of the Mesozoic Era. It took place around 199.6 to 146.5 million years ago, following after the Triassic period and before the Cretaceous period. During this time period, the supercontinent known as Pangaea broke apart. The Northern half, called Laurentia and would later part into North America and Eurasia, was starting to split. The tearing of this part of the continent also started to make way for water passages that would soon be known as the Gulf of Mexico and the Atlantic ocean. Meanwhile, the southern half, Gondwana, started to drift in a more eastern direction, slowly pulling apart in order to begin the creation of Antarctica, Madagascar, India and Australia. A more western portion of Gondwana
It has been known for well over a century now that the Earth’s core, mantle and the crust make up the basic structure of the Earth. However, there is some controversy over how and when the Earth produced its core, mantle and crust. In this essay, I will first discuss about the formation of the Early Earth and its Moon, then about the methods used to pinpoint the age of the Earth. Other than that, I will also expand on core and mantle formation, as well as the eventual production of the continental crust.
Glaciation that are widespread can be identified based on the subglacial tillite, which is a thick layer of sediments that settle down beneath glaciers or ice caps. On top of this subglacial tillite layer is deposited marine carbonate, also known as cap carbonate. Based on their paleolatitude designated by glacial sediments’ paleomagnetism, it can be determined that these deposits are from equator region. The interaction between two types of sediments, marine (like carbonate) and subgacially deposited sediments, indicate that the glaciers had approached marine coastlines.