10/3/17 1 Introduction to Oceanography • Lecture 3: The shape of the seafloor Map of the North Atlantic, 1957 by Marie Tharp and Bruce Heezen Geological Society of America Introduction to Oceanography 1. Attend Your Lab Section 1977 map of the North Atlantic. Berann, Tharp and Heezen. National Geographic Society
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Introduction to Oceanography - UCLAschauble/EPSS15_Oceanography/LEC3_F17_B… · Basalt hand specimen Oceanic vs. Continental Crust •Continental Crust –30-40 km thickness •Oceanic
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10/3/17
1
Introduction to Oceanography• Lecture 3: The shape of the seafloor
Map of the North Atlantic, 1957 by Marie Tharp and Bruce HeezenGeological Society of America
Introduction to Oceanography
1. Attend Your Lab Section
1977 map of the North Atlantic.
Berann, Tharp and Heezen. National
Geographic Society
10/3/17
2
What Planetary Bodies have Oceans?
• Definitely Earth!
NASA Image, Public Domain
Where does Earth’s water come from?
1.5´10-5 m
5´10-4 m
Most water probably came from water-bearing minerals in accreted planetesimals and comets. Such minerals are common in meteorites found today.
Green serpentine~Mg3Si2O5(OH)4
Murchison meteoriteU. Glasgow Earth Science Electron Microscopy lab.
Right-side images: M. Zolensky, NASA/JSC, Public Domain
Monahans meteorite fall fragment, held by Monahans, TX police officer Reggie Bailey. Photo by Mark Sterkel, Odessa American
• The Clark Iron (called Canyon Diablo) is a 357-pound meteorite in the center of the room. It was derived from a 300,000-ton projectile that formed Meteor Crater (the freshest impact crater on Earth) about 50,000 years ago in northern Arizona.
• The Camp Wood Iron is a 326-pound magmatic iron meteorite from Texas that crystallized in the molten core of a differentiated asteroid.
• The Gibeon Iron is a 811-pound magmatic iron meteorite from Namibia that crystallized in the molten core of a differentiated asteroid. It has the second or third largest total mass among collected iron meteorites,
Basic Structure of the Earth• Layers of increasing
density– Thin Crust
2.5 to 3.0 gm/cm3
– Rocky mantle3.2 to > 5 gm/cm3
– Metallic core >10 gm/cm3
Planetary Radius:6371 km
Core
Figure E. Schauble
Crust5-70 km
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Compositional Layers of Earth
Hand samples: Granite (cont’l. crust), Basalt (ocean crust), peridotite (mantle), iron meteorite (core)
• Thin crustal surface layer (almost all we see)Oceanic (basalt) ~8 km thickContinental (granite) ~35 km thick
• Mantle (silicate rock) – Bulk of planet’s volume