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The Drift Towards Plate Tectonic
Theory
From continental drift to a holistic understanding
of the whole Earth system — how plate tectonics
informs natural resource exploration.
By: Jean-Christophe Wrobel-Daveau and Graeme Nicoll
San Andreas Fault. https://en.wikipedia.org/wiki/San_Andreas_Fault#/media/File:Aerial-SanAndreas-CarrizoPlain.jpg.
From simple observations of the shape of the
continental margins across the Atlantic Ocean
to adding the crucial evidence from stratigraphy,
palaeontology, and geophysics, the theory has
evolved, finally gaining wide acceptance in the
late 1960s. In this article, we give an exciting
historical overview of this important milestone
and how it has impacted the way we conduct oil
and gas exploration. We also highlight the main
challenges and opportunities that lie ahead, as
academia and industry continue to evolve our
global understanding by linking more concepts,
like mantle dynamics, climatic changes, and sea
level perturbations, through plate tectonics.
FROM CONTINENTAL DRIFT TO
PLATE TECTONICS
The Early Days
was widely and often violently rejected by the wider
scientific community at the time, due to the lack of
better physical observations (Simmons, 2018).
Wegener believed that mid-oceanic ridges were
the location for the extrusion of fresh and fluid
new crustal material needed to make continental
drift possible. Therefore, oceanic and continental
crust had to be different in nature, and had to sit
on a material that had fluid properties based on
his understanding of isostasy. A whole series of observations was required to
confirm this hypothesis, including data on deep
ocean floors and the nature of oceanic crust.
More generally, the development of marine
geology gave evidence for the association of
seafloor spreading with mid-ocean ridges and
magnetic field reversals (Figure 3), as published
between 1959 and 1963 by Heezen and Tharp,
Deitz, Hess, Mason, Vine and Matthews, Morley,
and others.
How the Theory Drifted to Become Plate
Tectonics
In 1927, the British geologist, Arthur Holmes,
proposed a possible mechanism for Wegener’s
theory of continental drift. He suggested
that differential heating of the Earth’s interior,
generated by the decay of uranium and other
radioactive elements, caused convection in the
“substratum” (the mantle, in today’s terminology),
on which the continents floated (Figure 2).
Convection cells would be generated that could
drag continents apart, allowing new crust to rise
up and form.
Despite trying to propose hypothetical mechanisms
for the driving forces behind his theory of
continental drift, such as a centrifugal force or the
change in Earth’s axis of rotation, Wegener’s theory
As early as 1596, the Dutch map maker,
Abraham Ortelius, suggested that the Americas
were once joined to Europe and Africa, based
on the observation of their matching coastlines.
During the 17 th and 18 th centuries, various
workers proposed similar hypotheses, but
they remained speculative, due to the lack of
evidence and understanding of the larger driving
mechanisms behind continental separation.
In 1858, a French geographer and scientist,
Antonio Snider-Pellegrini, published La Création
et ses mystères dévoilés (The Creation and its
Mysteries Unveiled). This was a first attempt
at paleogeographic reconstruction, based on
observations of matching plant fossils between
Europe and the United States, as well as
matching fossils on all the continents (Figure
1). This reconstruction showed the continental
fit across the Atlantic Ocean, and even the
hypothetical position of Australia to the east of
Africa.
Alongside understanding geological time, the
advent of plate tectonic theory in the 20 th century
is arguably the most important advancement
in Earth science. The establishment of the
Earth’s evolution as a mobile phenomenon has
fundamentally changed our understanding of the
planet and revolutionized the predictive power
of applied geoscience, in a similar way to what
the discovery of DNA did for biology and human
medicine, and the heliocentric perspective did for
astronomy and space exploration.
It was Alfred Wegner, widely recognized as
the founding father of plate tectonics, who
in 1912 introduced the theory of continental
drift. He supported this idea using stratigraphic
information that had recently been published
about Cretaceous and Carboniferous deposits
from the continents surrounding the Southern
Atlantic. He showed that the continents had
once been conjoined using evidence of fossil
correlations, stratigraphic and mountain range
patterns, and paleo-climate markers. In his book,
The Origins of Continents and Oceans, first
published in 1915, Wegener proposed that the
continents had once formed a supercontinent
(“Urkontinent” in German; “Pangea” meaning
“all lands” in Greek) that started to split apart
approximatively 200 Ma.
Figure 1 > Reconstruction of the continental fit before the opening of the Atlantic Ocean and the present-day map (Snider-Pellegrini,
1858). (Source: https://commons.wikimedia.org/wiki/File:Antonio_Snider-Pellegrini_Opening_of_the_Atlantic.jpg).