The Magma Ocean Concept

Slides:



Advertisements
Similar presentations
Earth’s Layered Structure
Advertisements

Igneous Rocks and Classifying Igneous Rocks
The Layers of Earth Lexile 850L
Earth Structures Day 1.
Lunar Anorthosite Parent Magma COSMOCHEMISTRY iLLUSTRATED Lunar Anorthosites and the Magma Ocean Concept Anorthosite Lunar anorthosites are thought.
Minerals and Origin of the Moon Triana Henz. Formation Theories Fission Capture Co-formation Giant Impact.
The Lunar Interior A Presentation by Kyle Stephens October 2, 2008.
Chapter 5.1 – Igneous Rocks Magma – molten rock below Earth’s surface Lava – magma that flows out onto the surface Igneous rocks – rocks that form when.
Geology and petrology of enormous volumes of impact melt on the Moon: A case study of the Orientale Basin melt sea William Vaughan (Brown University) James.
Intro to Igneous Rocks.
Layers of the Earth 1. Crust 2. Upper Mantel 3. Transition Region 4. Lower Mantel 5. “D” layer 6. Outer Core 7. Inner Core
1 SGES 1302 INTRODUCTION TO EARTH SYSTEM LECTURE 14: Rock Cycle & Magmatism.
Journey to the Center of Earth
Section 1: Earth’s Moon Preview Key Ideas Exploring the Moon
Earth’s Interior (What’s down there below us?)
Ultramafic Rock Bodies
Igneous Rocks Mr. Ahearn Earth Science What are Igneous Rocks? Rocks that cooled and crystallized directly from molten rock, either at the surface.
STRUCTURE OF THE EARTH. Differentiation of Earth Earth is divided into layers based on density and composition Solid Layers – Core (iron-nickel) – Mantle.
Solid Earth System. The Earth is like an onion, it is made up of many layers. Although we have not been to the center of the Earth, Earthquakes, and volcanoes.
Earth’s Composition Standard S6E5
 The Moon (Latin: Luna) is the Earth's only natural satellite.[e][f][8] Although not the largest natural satellite in the Solar System, it is the largest.
Magma Oceans in the Inner Solar System Linda T. Elkins-Tanton.
Liquidus Projections for haplo-basalts The Basalt Tetrahedron at 1 atm: The olivine - clinopyroxene - plagioclase plane is a thermal divide in the haplo-basalt.
CHAPTER 5 – IGNEOUS ROCKS. WHAT ARE IGNEOUS ROCKS? Igneous Rock Formation  Igneous rocks form when lava or magma cools and minerals crystallize.  Most.
Jeff Taylor Pristine Highland Rocks1 Rock Names Ferroan anorthosite suite Mg-rich suite –Troctolites –Norites –Gabbro-norites –Others Evolved Lithologies.
The Chemical Layers of the Earth. What does this graph show us? Density of Earth as Distance from Core Increases.
Structure of the Earth. Earth’s Structure  The Earth is made up of several layers with distinct properties:  Crust = outer layer  Mantle = middle layer.
Layers of the Earth The Layers of the Earth are the Inner Core, Outer Core, Mantle and Crust.
The formation of MORB vs Ophiolites Anneen Burger Anhydrous Melting of Peridotite at 0-15 Kb Pressure and the Genesis of Tholeiitic Basalts A.L. Jaques.
EARTH’S INTERNAL STRUCTURE And processes. What Was Early Earth Like?  Describe what Earth was like right as the Solar System was forming?  Why did earth.
Intro to Rocks Major Rock Types: There are three major rock types
Section 1: What are igneous rocks?
The Layers of the Earth © Copyright 2006.  M. J. Krech. All rights reserved.
The Earth’s Layers Scientists have spent many years determining what is inside the earth. Geologists can’t use x-rays to see inside the earth or.
Chapter 5 Igneous Rocks Section 5.1.
Solid Earth System.
Chapter 4.
Moon’s Pink Mineral ALH 81005
Section 1: Earth’s Moon Preview Key Ideas Exploring the Moon
Section 1: Earth’s Moon Preview Key Ideas Exploring the Moon
EARTH’S STRUCTURE.
Igneous Rocks.
Igneous Rocks.
A Sample from an Ancient Sea of Impact Melt
Ch. 4/5 Notes Day 1 10/26/16.
Geology Thinking Sheet 11/29/17 or 11/30/2017
The Magma Ocean Concept
Integrated Science C Mrs. Brostrom
Geology Thinking Sheet 12/1/17 or 12/4/17
Time to Solidify an Ocean of Magma
Formation of Stony-Iron Meteorites in Early Giant Impacts
Iron-Titanium Deposits in Anorthosite Complexes
What are Igneous rocks? Chapter 5 Section 1.
Damp Moon Rising Overview: The discovery in 2008 by Alberto Saal (Brown University) and colleagues that lunar volcanic glasses contain water surprised.
Water Inside Mars Enriched Shergottites: High La/Yb
Age Rules The ages of rocks from the lunar highlands vary widely, making it difficult to test ideas for early lunar differentiation and crust formation.
Unraveling the Origin of the Lunar Highlands Crust
3.2 – Igneous Rocks.
The Earth’s Layers Scientists have spent many years determining what is inside the earth. Geologists can’t use x-rays to see inside the earth or.
Chapter 2, Lesson 3, Earth’s Interior
Earth’s Interior Chapter 2 Lesson 2
Section 1: Earth’s Moon.
Earth Science Chapter 3 Section 2
Volatile Elements Test Models for the Origin of the Moon
Formation of Igneous Rocks
Earth’s Composition Standard S6E5
Igneous Rocks Chapter 5.
Layers of the Earth.
Chapter 2, Lesson 3, Earth’s Interior
Presentation transcript:

The Magma Ocean Concept Overview: A central tenet of lunar science is that the Moon was surrounded by a huge ocean of magma when it formed. Originally thought to be a few hundred kilometers deep, lunar scientists now think that the entire Moon was initially molten. Numerous geochemical models have been constructed for the crystallization of the magma ocean. All the calculations use computer programs based on experimental data, but these necessitate some simplifications. Stephen Elardo, David Draper, and Charles Shearer (all at the University of New Mexico, though Draper has moved to the Johnson Space Center) are tackling the problem differently by doing a series of high-temperature experiments at different pressures and two different starting compositions to improve our understanding of how the magma ocean crystallized.   Their first results show that both starting compositions (one enriched in aluminum and other refractory elements and one not enriched compared to Earth) produce an extensive olivine-rich cumulate pile inside the Moon that rests on a metallic iron core. The composition with the higher aluminum concentration produces a thicker crust than does the other composition, raising the possibility that we can determine the bulk composition of the Moon by pinning down the thickness of the primary crust of the Moon. The olivine deposit is less dense than the overlying rock, so would likely slowly move as large blobs before stalling at the base of the crust. Once there it could react with feldspar-rich rock and KREEP (dregs from extensive magma ocean crystallization) to produce the magmas that gave rise to the numerous igneous rock bodies known as the magnesian suite. Images: Left: The idea that the Moon melted substantially (probably completely) when it formed, nicknamed the "magma ocean concept," is an important theory in lunar and planetary science. These three panels, from left to right, illustrate the lunar magma ocean theory. The basic idea suggests that as the molten Moon crystallized, minerals less dense than the magma floated and the heavier ones sank. The lighter minerals formed the primary crust of the Moon. Of course, the real magma ocean was much more complicated than this simple picture. Right: Results of a cosmochemical calculation showing crystallization sequences of the lunar magma ocean, a vertical view, with the first-formed crystals closest to the bottom. Plagioclase feldspar begins to form after about 75% of the magma has crystallized, and ends up floating, so appears at the top. The region labeled "pig, cpx, ilm" would contain pigeonite (pig), high-calcium clinopyroxene (cpx), and ilmenite (ilm), and would have high concentrations of zirconium, rare earth elements, and other elements that do not enter olivine, orthopyroxene (opx), or plagioclase (plag). Reference: Elardo S. M., Draper D. S., and Shearer C. K. 2011. Lunar magma ocean crystallization revisited: Bulk composition, early cumulate mineralogy, and the source regions of the highlands Mg-suite. Geochimica et Cosmochimica Acta 75: 3024–3045, doi: 10.1016/j.gca.2011.02.033. The lunar magma ocean crystallized sequentially, producing a mineralogically and compositionally zoned cumulate pile. Magma Ocean Experiments

Equilibrium Crystallization Sequence Images: Left: Temperature versus pressure diagrams based on Steve Elardo’s experiments for the Taylor Whole Moon (TWM) and Lunar Primitive Upper Mantle (LPUM) compositions. The diagrams show which minerals are present at different temperatures and pressures. Everything is liquid above the “liquidus” curve and everything is solid rock below the “solidus” curve. The crystallization order at a given pressure can be determined by following a straight line from the liquidus to the solidus. A major difference in the two compositions is the presence of the spinel (an aluminum-rich mineral) at less than 2 GPa in the TWM composition, but not in the LPUM composition. This reflects the higher aluminum in the TWM composition. Right: Cross section of the Moon after 50% crystallization of magmas with the TWM (left) and LPUM (right) compositions. In both cases, the solid pile of accumulated crystals (“cumulate pile”) is composed mostly of olivine, with a smaller amount of orthopyroxene and even smaller amounts of spinel and garnet (depicted as orange and bluish blebs in the green cumulate pile). The mineral abundance calculations are based on the temperature-pressure diagram on the left. The orange region on top is the residual magma ocean after 50% crystallization. The big difference between the two compositions is the higher Al2O3 content in the TWM composition compared to the LPUM composition (11.6 wt% vs 7.9 wt%) and in the CaO concentration (9.1 wt% vs 6.1 wt%), another refractory element enriched in the TWM composition. Good references for the two compositional models: Longhi, John (2006) Petrogenesis of Picritic Mare Magmas: Constraints on the Extent of Early Lunar Differentiation. Geochemica et Cosmochimica Acta, v. 70, p. 5919-5934. Taylor, S. R., Taylor, G. J., and Taylor. L. A. (2006) The Moon: A Taylor Perspective. Geochemica et Cosmochimica Acta, v. 70, p. 5904-5918. Crystallization sequences for two proposed lunar bulk compositions, one rich in refractory elements compared to Earth (TWM) and the other more like the Earth (LPUM). Magma Ocean Experiments

Rising Diapirs and Formation of the Mg-Suite Left: Model devised by Elardo, Draper, and Shearer for creation of a hybrid, shallow source for production of Mg-suite magmas. Right: Schematic showing how the three major magma ocean products could react to make a hybrid source for the Mg-suite magmas. Rising magnesian cumulates from the magma ocean slowly smash into the KREEP layer (last magma ocean magma remaining, and possibly still partly molten) and near the anorthosite crust where all three react to form a hybrid rock. This rock subsequently partially melts to produce the Mg-suite magmas, which are characterized by high Mg/Fe, high concentrations of incompatible trace elements such as the rare earths, and crystallize plagioclase feldspar and either olivine or pyroxene at about the same time. Formation of the magnesian suite has been confusing since it was identified in the early 1970s. Its most interesting characteristic is that magnesian suite rocks are indeed magnesian (high Mg/[Mg+Fe]) compared to other lunar rocks (ferroan anorthosites and mare basalts especially), yet they contain much higher concentrations of incompatible elements than do other lunar rocks. This paradoxical situation led to two main ideas for their origin. (1) Magnesian magmas formed by overturn of magma ocean cumulates, which rise, partially melt, then react with residual magma ocean products rich in incompatible elements. (2) The late-stage, trace-element rick magma ocean products sink and hybridize with magnesian early cumulates. Both have difficulties, which led Elardo and colleagues to their new model. Rising diapirs of olivine-rich, magnesian cumulate rocks stall near the crust/mantle boundary and react with KREEP and crustal anorthosite. Magma Ocean Experiments