Is Palisades Complex (Complex?)

1
X-Ray Diffraction Study of Minerals Produced in a
Large Volcanic Eruption By Junior
NkrumahMentor Dr. Jeff Steiner
2
The Purpose

• To better understand how large igneous rock
  bodies form by studying the compositional changes
  of basalt in the sill

3
The Study Area
Large Underground Eruption near Nyack, New York
showing Layering
Layers of Basalt in the Palisades Sill, Nyack NY
4
What Is a Basalt
Before
After

• A basalt rock is a common gray to black volcanic
  rock. basalt Is a hard, black volcanic rock with
  Less than about 52 weight percent silica so it
  can flow more easily. Basalt major Minerals Are
  Pyroxene and Plagioclase.

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The minerals under investigation

• A pyroxene is a mineral that is found in many
  igneous rocks such as basalt
• This mineral contains high quantities of FE and
  Mg
• Plagioclase is a mineral in the feldspar group
  which makes up 60 of earths crust.
• Plagioclase is rich in aluminum and silicon

dense heavy
www.proxyene pictures.com
light
6
X-ray Diffraction Identifying Minerals

• X-ray diffraction is used to determine mineral
  structure.
• Once the structure is recognized, the mineral is
  identified
• N(lambda)2(d)sinthetaThe Bragg Equationthe
  basis for XRD

7
Results
intensity
2-theta angle

• X-ray diffraction patterns for 3 basalt samples
• The peaks represent the minerals pyroxene and
  plagioclase
• Notice the difference in minerals present
  indicated by the labeled peak