Transcript The true cause of the KT Extinctions of 65mya.

Plate tectonics of the North
American Continent at the
Cretaceous-Tertiary Boundary,
and Implications For a
Terrestrial Cause in the
Great KT Extinction Controversy
The Great KT Extinction Controversy
• Before 65 mya, during the Cretaceous (K),
dinosaurs had roamed the Earth.
• But by the beginning of the Tertiary (T),
65 million years ago (mya), a mass
extinction had occurred that wiped out
nearly 75 % of life on Earth, including the
dinosaurs.
• This is known as the KT Extinction Event
• In 1980, Dr.’s Louis and Walter Alvarez
discovered a layer of clay at several sites
along the KT boundary that contained
high levels of iridium, as well as other
exotic materials. (Alvarez, 1980)
• Since iridium is rare in Earth’s crustal
rocks, the Alvarez team proposed that the
layer had been formed by an
Extraterrestrial source, such as an
asteroid.
• So far, this has been the most widely
accepted hypothesis.
• In 1981, however, Dr. Dewey McLean of
Virginia Tech showed how Deccan Traps
volcanism in India could have increased
CO2 levels in the atmosphere causing a
severe global warming event.
(McLean, 1981)
• Dr. McLean also showed that the asteroid
theory did not explain all of the evidence
found in the geologic and biologic record
at the KT boundary.
(McLean, 1991)
• For decades now, these two hypotheses
have battled for top contender in the
Great KT Extinction Debate, and yet,
neither has been chosen as the champion.
• This presentation will attempt to
show that this is because it was
neither an asteroid nor the Deccan
Traps that caused the extinctions of
65 million years ago.
• In 1996, a new hypothesis was introduced that
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almost seemed to go unnoticed in the KT
Extinction Debate.
In their book, “The Great Dinosaur Extinction
Controversy”, Dr. Charles Officer and Jake Page
showed that most of the evidence being used in
the asteroid hypothesis could also be volcanic in
nature.
They also pointed out that not only were the
Deccan Traps occurring at the KT boundary, but
that massive volcanism was occurring all over
the world at that time.
(Officer and Page, 1996)
•Particularly, large
magmatic events
were occurring
within North
America that was
not only coeval with
the Extinctions, but
also, with the
uplifting of the
Laramide Orogeny
and the
disappearance of
the Western
Interior Seaway.
• However, as no exact mechanism had
been found to account for the exotic mix
of materials in the KT boundary layer, this
hypothesis was largely dismissed in the KT
Extinction Debate.
•So, I wanted to know what DID cause
the uplifting of the Rocky Mountains, as
well as the disappearance of the Western
Interior Seaway, along with massive
volcanism, to occur in North America at
the KT boundary?
• I began to look at the Geologic
formations of Western North America at
the Cretaceous-Tertiary Boundary and
the tectonic events that created them.
The Western Interior Seaway
• Before the beginning of the Laramide, Texas lay
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at the bottom of a shallow seaway that
stretched across the interior from the Arctic
Ocean to the Gulf of Mexico. This cold, salty sea
is known as the Western Interior Seaway.
Before the Laramide, bays and estuaries covered
most of New Mexico (Chronic, 1987); and
Arizona lay along the floodplains of that ancient
sea. (Chronic, 1983)
•Most of the
fossils found at
the KT boundary
in North America
were animals
that lived within,
or along the
shores of, the
Western Interior
Seaway.
North America
in the Age of the
Dinosaurs,
75 mya. (National
Geographic,
January, 1993)
• Officer and Page (1996) showed that the
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Western Interior Seaway began to disappear in
the Albian and was mostly gone by the
Maastrichtian, before 65 mya, caused by the
uplifting of western North America.
meaning that critical habitats, and indeed, entire
biospheres had disappeared before the KT
boundary.
JD Archibald, has pointed out that 75% of our
knowledge of dinosaurs immediately before the
KT boundary comes from within the Western
Interior of North America. (Archibald, 1997)
The Laramide Orogeny
• The Laramide Orogeny, or uplifting of the
Rocky Mountains, began within the interior
of the continent at ~80 mya and lasted
until ~50 mya.
• However, many major thrusting events
occurred directly at the 65 my boundary.
• Laramide magmatic trend dated between 64 and
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69 mya. (Officer and Page, 1996)
The Black Hills, along with the rest of Wyoming
and Montana, weas uplifted between 72 and 58
mya.
New evidence shows that the Kaibab plateau,
which was uplifted along with the rest of the
larger Colorado plateau, had uplifted as early as
65 mya. (National Geographic, 2007)
Carlsbad Caverns in New Mexico was formed
within the limestone of an ancient coral reef that
was uplifted at the KT boundary and filled with
sulfuric acid (H2O + sulfur) that ate away the
limestone. The formation of the caverns
themselves began ~60 mya. (National Park
Service, 2006)
• And in Texas, we find the actual edge of
the continent, or Cretaceous shelf. The
Balcones Escarpment was uplifted at the
KT boundary, along with the rest of
western North America.
• From the Balcones fault to the Gulf Coast,
at least one-third of Texas sits upon
Tertiary or younger sediments that were
deposited as the Rocky Mountains uplifted
to the west and the sediments drained
into the Gulf. (Chronic, 1987)
So then, I wanted to know what
exactly caused the Laramide Orogeny?
• The Laramide had its beginnings within
the interior at ~80 mya.
• This age would just happen to coincide
with the formation of the Sierra Nevada
batholith on the west coast, as the magma
beneath this arc stopped melting and
solidified into granite.
Many scientists today
believe that the Laramide
was caused by the flatslab subduction of the
Farallon plate.
However, remnants of the
Farallon are still
subducting beneath North
America, and as far as we
can tell, they are not flat.
So then, what caused the
slab to go flat at the KT
boundary?
(Oceanography, 4th ed., Garrison)
• One study shows that "Subduction of an
oceanic plateau about 85-65 Ma
(remnants in the Franciscan) produced
east-vergent tectonic wedging in the Coast
Ranges, possible thrusting along the
eastern Sierra Nevada Batholith margin,
and development of Rocky Mountain
Laramide structures. The ‘Laramide
Orogeny’ is herein redefined to include all
Late Cretaceous-early Tertiary (75-45 Ma)
fold thrust structures from the Pacific
Coast to the Rocky Mountains.“
(Moores, Wakabayashi, and Unruh, 2003)
It is within the
Franciscan
melange that
we find our
clues to what
really happened
at the KT
boundary.
On the west
coast of North
America,
we can still see
the scar.
(Scripps
Institute of
Oceanography)
The Coast Range Ophiolite represents a piece of
Jurassic age oceanic crust that was uplifted onto
the North American continent.
The Great Valley Sequence represents the
sediments that were deposited on that ocean
floor while it still lay within the ocean.
Structurally, the Franciscan lies beneath the Coast
Range Ophiolite and Great Valley Sequence in
California.
The Franciscan is a melange, or mixture of
differing materials: greywacke, greenstone,
chert, and serpentinite.
USGS
Professional
Paper 1515,
The
SanAndreas
Fault.
Geologic sketch map
of California,
Based on U.S.
Geological Survey
(1966), Jennings
and others (1970),
and Ross (1984).
Greywacke
One study shows that one sandstone
sequence found within the Franciscan is
volcanic in nature and “concluded that
these rocks were deposited on the flank of
an oceanic rise or plateau….”
This study also showed that the sandstone
is similar in chemistry to the Greenstones
found in the Permanente terrane of
California.
(Larue and Sampayo, 1990)
Greenstone
The Greenstone found within the Franciscan
is…”an altered oceanic pillow basalt
believed to have been formed during the
Jurassic and Cretaceous far out in the
Pacific along a spreading oceanic ridge.”
(Mount Diablo Interpretive Association)
Manganiferous Cherts
• One study shows that the cherts found
within the Franciscan are manganiferous,
and were also formed on the flanks of a
mid-ocean ridge. (Crerar, 1982)
• Manganese is known to emanate from
hydrothermal vents along mid-ocean
ridges today.
The Caleras limestone
“Jenkyns 1980), Sliter (1984), and Tarduno,
et al., argues that the Caleras limestone
was deposited on top of an oceanic rise or
plateau during the Late Cretaceous and
was subsequently transported NE until it
was accreted to the North American
continental margin about 65 mya.”
(in Larue and Sampayo, 1990)
• One study shows
that a Jurassic age
hydrothermal vent
community has been
found within the
Franciscan, similar to
those found around
the Galapagos
Islands today.
(Little, Danelian,
Herrington and Haymon,
2004)
• The Franciscan, then, would seem to show
all of the evidences of being a mid-ocean
ridge AND associated ocean-island plateau
(hotspot), similar to today’s Galapagos
Islands.
• But if the Franciscan does indeed
represent an oceanic plateau and midocean ridge segment, WHEN, exactly did it
subduct beneath North America?
The Great Valley Sequence that lay on top
of the Coast Range Ophiolite has been
dated from ~140-65 mya.
• Meaning that these sediments had been
accumulating for ~75 my.
• But by 65 mya, the GVS had been uplifted
and was subject to erosion. (Mount
Diablo)
• Major Franciscan uplift ca. 65 mya, coeval
with graben formation within the CRO, at
the KT Boundary
(Moxon and Grahamm, 1987; Unruh,
Dumitru and Sawyer, 2007)
• Coast Range Thrust/Great Unconformity65 mya (Moores)
• Franciscan cooling ages ~61 mya (Unruh,
et al., 2007)
• Los Angeles, Santa Barbara and Ventura
all sit on top of thick Cretaceous-Tertiary
sediments. (USGS Prof. Paper 1515)
• Wakabayashi
showed that the
Salinian block
collided with the
Franciscan ~60-50
mya.
(Wakabayashi,
1988)
• Vedder, Howell and
McLean (1983)
shows that
thrusting on the
Salinian occurred
from 65-55 mya.
• As the Salinian block collided with the
Franciscan, the MOR/hotspot would have
been trapped within a backarc basin
between the Salinian block on the west
and the subduction zone/Coast Range
Ophiolite/Sierra Nevada on the east.
• As the hotspot/MOR moved was thrust
beneath the continent, it would move in
beneath the downgoing plate, thereby
causing the flat-slab subduction that
moved the Laramide into the Interior.
This event is what caused the Coast Range
Thrust on the west coast, the uplifting of
the western half of North America continent,
as well as the disappearance of the Western
Interior Seaway, at the Cretaceous-Tertiary
boundary.
The current presentation will suggest that
this event also caused the deposition of the
KT boundary layer, as well as the extinction
of the dinosaurs, 65 mya.
All of the materials being used to describe
the asteroid, can also be explained by the
closing off of a mid-ocean ridge and/or
ocean island hotspot.
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Iridium
Glass spherules
Shocked quartz
Granite
Andesite
Iridium
• Member of the platinum group with
platinum, osmium and rhenium
• Denser than iron or nickel, therefore,
would sink to the bottom of the mantle
(ie.mantle/core boundary)
• Brought to the surface by certain types of
volcanic eruptions (mantle plumes)
• One study shows that rare OsIrRu minerals have been
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found uplifted in the Josephine Ophiolite of Oregon
and northern California.
The authors of this study show that “…an ancient
platinum group element reservoir with a suprachondritic Pt/Os… exists within the mantle. (Meibom
and Frei, 2002). And also, that the rare OsIrRu grains
were “…transported from the core-mantle boundary
region to the lithosphere as xenoliths in a mantle
plume/convection system.”
(Bird, Meibom, and Frei, and Nagler, 2002)
The Josephine ophiolite is related to the Coast Range
Ophiolite, and was uplifted along with it at the KT
boundary.
Glass Spherules
• Glass spherules can also be created by
volcanic processes as magma comes into
contact with water. The magma cools
rapidly on contact, creating the spherules.
The ocean floors surrounding seamounts
are often littered with glass spherules.
• Within the Franciscan, the Stonyford
volcanic complex is an ancient seamount
that was accreted onto California. It is
surrounded by glass spherules.
• One study shows that the glass spherules
found within the KT boundary layer are
altered oceanic basalt. This is why it is
believed that the asteroid must have hit
within an oceanic basin.
• (Montanari, Hay, Alvarez, Alvarez, Asaro,
Michel, and Smit, 1983)
• This study also shows that the spheroids
are K-feldspar and pyrite, which is also
found on the west coast.
“Shocked” quartz
• Shocked quartz can also be created by
geologic processes.
• Also found in uplifted ophiolites.
• The greywacke of the Franciscan consists
of abundant angular quartz.
• Deformation lamellae is present in quartz
grains within the Franciscan. (Schemann,
Unruh and Moores, 2008)
• Miller shows that at 67 mya, sea levels
dropped dramatically, but that by 65 mya,
sea levels had returned to near normal.
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• Between 67 and 65 mya, oxygen levels dropped
from 35 parts per million to 27 ppm (Dowswell, )
• Dr. Gerta Keller showed that foraminefera began
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disappearing from the record 500,000 years
before the KT boundary. (Keller, 2000 )
In the oceans, high levels of CO2 cause calciumbodied plankton to dissolve at depths of greater
than 4500 ft below sea level.
This could show that CO2 was increasing in the
ocean waters at the same time that oxygen
levels were decreasing in the atmosphere,
before the KT boundary.
The Real Killer?
• Zoller studied the fine particle emissions of the
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Kilauea eruption of 1983 and found high levels
of Iridium, as well as high levels of selenium,
arsenic, and fluoride. The presence of fluoride
lead these authors to believe that the Iridium
was released as Iridium hexafluoride. (Zoller,
1983)
The high levels of selenium could provide a clue
as high levels of selenium have also been found
in dinosaur eggshells at the KT boundary.
• If the iridium was separated from the
hexafluoride…….Hexafluoride combines
with Selenium to become a poisonous gas,
Selenium hexafluoride; which causes
severe skin irritation, breathing difficulties
and respiratory failure leading to death.
• Dinosaur skeletons have been found at the
KT boundary with arched backs as if they
were convulsing from poisoning or
asphyxiation.
• High levels of
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selenium are still
found today in KT
boundary soils.
This map shows
where seleniferous
plants in North
America today are
still causing trouble
for cattle and other
wildlife.
• Open dots-50-500 ppm
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selenium
Black dots-more than
500 ppm selenium
(Rosenfeld and Beath,
1964, In Officer and
Page, 1996.)
Chixculub crater
• Dr. Charles Officer, along with many
others, spent years trying to prove that
the Chixculub crater was a volcanic
structure.
• I will not argue here whether the
Chixculub represents an asteroid crater or
not.
But, IF an asteroid did strike the Gulf at 65
mya, it did NOT cause :
• the uplifting of the entire ocean floor on the
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west coast,
the uplifting of the western half of the North
American continent;
the disappearance of the Western Interior
Seaway;
the change in oxygen/CO2 levels;
the drop in sea levels;
the volcanism that was occurring throughout the
world at that time;
OR the Extinctions that were already occurring
hundreds of thousands of years before it hit.
• The evidence presented herein
will hopefully show that it was
the subduction of a mid-ocean
ridge and ocean island plateau
on the west coast of North
America that DID, 65 million
years ago.