Establishing Geochemical Constraints on Mass Accumulation Rates Across the Cretaceous ...

75 Pages·2014·5.7 MB·English

Establishing Geochemical Constraints on Mass Accumulation Rates
Across the Cretaceous-Paleogene Boundary With Extraterrestrial
Helium-3
by
Marie Minh-Thu Giron
B.S. Geology
California Institute of Technology, 2009
SUBMITTED TO THE DEPARTMENT OF EARTH, ATMOSPHERIC AND
PLANETARY SCIENCES IN PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF
MASTER OF SCIENCE IN EARTH AND PLANETARY SCIENCES
at the
UILJh
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
SEPTEMBER 2013
©2013 Massachusetts Institute of Technology. All rights reserved.
Signature of Author:
Depart ef Earth, At eric and P anetary Science
August 26 13
Certified by:
(3
Roger E. Summons
Professor of Geobiology
Thesis Supervisor
Accepted by:
Robert van der Hilst
Department Head of Earth, Atmospheric and Planetary Sciences and
Schlumberger Professor of Geophysics
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Establishing Geochemical Constraints on Mass Accumulation Rates Across
the Cretaceous-Paleogene Boundary With Extraterrestrial Helium-3
by
Marie Minh-Thu Giron
Submitted to the Department of Earth, Atmospheric and Planetary Sciences
on August 26, 2013 in Partial Fulfillment of the Requirements for the
Degree of Master of Science in Earth, Atmospheric and Planetary Sciences
Abstract
Records of ocean biogeochemistry in marine sediments show shifts across the
Cretaceous-Paleogene boundary (K-Pg) that are simultaneous with the extinction event
and onset of the boundary clay deposition. However, the timescale of these records is
difficult to determine near the boundary because of fluctuating sedimentation rates and
the short duration of the event. In this study, we have used extraterrestrial helium-3 as a
constant flux proxy for instantaneous mass accumulation rates in four marine sections:
Caravaca, Spain; El Kef, Tunisia; and Hojerup and Kulstirenden, Denmark. These
sections are characterized by a thick boundary clay layer and, therefore, are more suitable
than many other proxies for high-resolutions studies. In order to better understand the
extent of the impact-related perturbations in different paleoenvironments, we performed a
high-resolution analysis at Caravaca and lower-resolution analyses at the other three
sections. We find that Hojerup and Kulstirenden are not suitable for this analysis due to
the probable variation in the flux of extraterrestrial helium-3 as a result of lateral changes
in sedimentation rate. Our results suggest that carbonate burial, and likely carbonate
production, were more severely affected with increasing paleolatitude. However, the
unique depositional environments are probably much more important than just
paleolatitude alone. We calculate boundary clay durations of Caravaca and El Kef of
6.45 (h 0.86) kyr and 6.28 (± 1.03) kyr, respectively. These results are consistent with
other studies and indicate a uniform, global deposition of the boundary clay and a rapid
recovery of carbonate burial in the marine ecosystem after the Cretaceous-Paleogene
extinction event.
Thesis Supervisor: Roger E. Summons
Title: Professor of Geobiology
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Acknowledgements
There are many people whom I need to thank for contributing to my growth as a scientist
and engaged citizen of the world. I would first like to thank my thesis supervisor, Roger
Summons, for giving me the opportunity to study at such a unique and stimulating
institution. I learned a great deal working in E25, and the lessons learned are not limited
to the earth sciences. I am grateful to my mentor, Julio Sepinlveda, for introducing me to
the wonderful world of the Cretaceous-Paleogene and patiently supporting and teaching
me. I am extremely thankful for the experiences I had in the field in Tunisia and Spain
that he made happen. I thank Sujoy Mukhopadhyay for advising me on this project,
analyzing my samples, and allowing me to expand my skill set. I would also like to
thank David McGee for being available as a resource and providing useful feedback.
I can say without a doubt that this thesis would not have been completed on time without
the support of my thesis-writing buddies, Sara Lincoln and Alex Evans. I am eternally
grateful that Sara has been my mentor, advocate, big sister, and friend, and I cannot
imagine having gone through this experience without her. I am thankful to Alex
introducing me to the MIT Graduate Student Council, an experience that has changed my
career plans if not my life. I thank him for showing me what true productivity and hard
work look like and for working by my side during the daytime and occasionally through
the night.
I thank my Graduate Student Council family for opening my eyes to the fulfillment that
results from passion and service. My experience serving on the GSC lit a fire in me, and
I hope that fire never dies. I especially thank my Activities Co-Chair, Alex Guo, for
being a friend and sister. I have never enjoyed working with a partner so much, and I
hope this is not the end of our partnership.
I am lucky to have such wonderful friends, and I thank all of them for making me smile
and take a break from perfecting my stress lines. I thank my roommates, Cristina
Camayd, Michelle Lira, and Monika Avello for their patience, love, and support. I thank
Bomy Lee Chung, Angela Laurance, Florence Schubotz, Helen Feng, Sharon Newman,
Ross Williams, Yodit Tewelde, and Ruel Jerry for being great friends, especially during
stressful times.
I finally thank my family for their support and unconditional love.
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Table of Contents
Chapter 1: Introduction.............................................................................................. 9
Cretaceous-Paleogene M ass Extinction.................................................................. 9
M arine Ecosystem Recovery .................................................................................... 12
Outline of Thesis................................................................................................... 14
Chapter 2: Analytical Background........................................................................... 15
Extraterrestrial Helium -3 ....................................................................................... 15
A pplication of the Extraterrestrial Helium -3 Proxy.............................................. 18
Chapter 3: Experime ntal Procedures. ..................................................................... 21
Sam ple Background............................................................................................... 21
Sam ple Preparation.............................................................................................. 23
H elium A nalysis................................................................................................... 24
Chapter 4: Cretaceous-PaleogeneS ections ............................................................. 27
Caravaca, Spain......................................................................................................... 28
El Kef, Tunisia ................................................ 30
Stevns K lint, D enm ark.......................................................................................... 32
Chapter5 : Results and D iscussion.......................................................................... 37
Caravaca, Spain......................................................................................................... 41
El Kef, Tunisia ................................................ 46
H ojerup, D enm ark................................................................................................. 50
Ku lstirenden, D enm ark .......................................................................................... 52
Conclusion. ................................................................................................................... 65
References..................................................................................................................... 67
Appendix ....................................................................................................................... 73
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Chapter 1: Introduction
Cretaceous-PaleogeneM ass Extinction
The Cretaceous-Paleogene (K-Pg) mass extinction event is the most recent of
Earth's 'big five' Phanerozoic mass extinction events and occurred 66 million years ago
(Figure 1) [1-3]. Evidence for the global K-Pg extinction event is clearly seen in the
fossil record with the disappearance of Mesozoic species and the appearance of Cenozoic
species, and it is estimated that at least 60% of all species went extinct within just a few
million years [4]. Groups that underwent severe extinction include calcareous
nannoplankton [5], planktic foraminifera [6], and dinosaurs [7]. This mass extinction
was a critical event in the history of the Earth and changed the course of biological
evolution.
The most significant trigger of the extinction is widely accepted to be a bolide
impact that struck near the present day Yucatan Peninsula and formed the Chicxulub
Crater (Figure 2) [4, 8]. Evidence for this catastrophic and contemporaneous impact is
seen worldwide in marine sediments and includes the famous iridium anomaly
discovered by Alvarez et al. [9]. The presence of ejecta spherules, Ni-rich spinels, and
shocked minerals also support an extraterrestrial impact, and they are found in the highest
concentrations nearest the Chicxulub Crater [4]. The prolonged eruption of the Deccan
Traps in India and the resulting environmental effects may have also contributed to the
mass extinction [10]. The extraterrestrial impact had global effects, the most immediate
of which was the injection of dust and aerosols into the atmosphere [11]. The impact
ejecta and the sulfur aerosols formed from volatilization of impacted anhydrite deposits
9
600
J
550 Late Ashgillian Djhulfian 5 Maastrichtian
0
Sooo L (end Ordovician) (end Permian) (end Cretaceous)
4500
W- 2 Late Frasnian 4 Late Norian
400 (Late Devonian) (end Triassic)
C 0
2 50
0~)2 0250 o IA
0
1500 L EL A
B M[
100
0 1 1 ~ ~
S0 01~~~ - - . . 0--
Ord S Dev Carb Perm Tri Jur Cret Pgn N
~
0 o o q 0 ~ 0 t 0 00* 0Q 0 0 tO'*-0 0 0 N
q# ~ C~30) C (0 0 N N N N 01- - -
Millions of Years Ago
Figure 1. Diversity throughout the Phanerozoic. Arrows point to the 'big five' mass
depletions and extinctions. Figure taken from Bambach et al., 2004 [12].
drastically reduced the intensity of solar insolation at the Earth's surface [11]. This
resulted in a transient devastation to primary productivity [11] and possible nutrient
scarcity at higher trophic levels [13], although this continues to be much debated [14].
Another proposed factor that contributed to decreased insolation was soot produced by
widespread wildfires [15]. The resulting 'nuclear winter' caused short-lived cooling [16],
contributing to ecosystem instability.
Another proposed effect of the impact was acid rain resulting from the regional
production of nitrous and nitric acid by both heating of the atmosphere [17] and wildfires
[18] and from the production of sulfuric acid from the sulfate aerosols mentioned above
[11]. Local weathering [17] and surface ocean acidification [14] may have increased as a
result of the acid rain, making some environments toxic. The immediate effects of the
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