Neoproterozoic to Holocene tectonothermal evolution of the southern Cantabrian Mountains NW Iberia, revealed by apatite fission track thermochronology [Elektronische Ressource] / vorgelegt von Kevin L. Carrière

Kcarriere

Informations

• Publié par: ruprecht-karls-universitat_heidelberg
• Publié le: 01 janvier 2006
• Nombre de lectures: 11
• Langue: English
• Poids de l'ouvrage: 18 Mo

Extrait

Neoproterozoic to Holocene tectonothermal
evolution of the southern Cantabrian Mountains
NW Iberia, revealed by apatite fi ssion-track
thermochronology
Inaugural-Dissertation
zur
Erlangung der Doktorwürde
der
Fakultät für Chemie und Geowissenschaften
der
Ruprecht-Karls-Universität
Heidelberg,
Deutschland
vorgelegt von
Kevin L. Carrière
aus Windsor Ontario,
KanadaIch erkläre hiermit, daß ich die vorgelegte Dissertation selbst verfaßt und mich dabei
keiner anderen als der von mir ausdrücklich bezeichneten Quellen und Hilfen bedient
habe.
Ich erkläre hiermit, daß ich an keiner anderen Stelle ein Prüfungsverfahren beantragt
bzw. die Dissertation in dieser oder anderer Form bereits anderweitig als Prüfungsarbeit
verwendet oder einer anderen Fakultät als Dissertation vorgelegt habe.
Heidelberg, den 16. Mai, 2006.
Gutachter 1: Prof. Dr. Günther A. Wagner
Forschungsstelle Archäometrie der Heidelberger Akademie der Wissenschaften
am Max-Planck-Institut für Kernphysik
Saupfercheckweg 1, D-69117, Heidelberg
Deutschland
Gutachter 2: Priv. Doz. Dr. Uli A. Glasmacher
Geologisch-Paläontologisches Institut
Ruprecht-Karls-Universität
Im Neuenheimer Feld 234, D-69120, Heidelberg
Deutschland
Tag der Promotoinsprüfung: 10. Juli, 2006.
iiiDelightfully though, the roads never lead where they’re supposed to go.
ivA mon oncle Irvin
vAcknowledgements
To arrive at this point has taken a lifetime, some discipline, some focus, but mostly
diligence and a self belief. Though this has ultimately been an personal journey, my
thanks stretch far. Many, knowingly or not, have impressed a profound and lasting
wisdom on which I’ve drawn upon for guidance in what has thus far been an adventurous
path to knowledge. So, though I cannot mention all who’ve left their impression, I’d like
to mention some of those whose efforts have helped in the completion of this work.
Thanks Mom and Dad for setting the path to knowledge, and for supporting the
adventures in their many forms.
Credit goes to the teachers at St. Joseph’s Elementary School and Saugeen District
Secondary School for laying the educational foundation; special thanks to Mrs. Smith,
for seeing potential and pushing me to actualise it; Thanks Mr. Parker for seeding ideas
and facilitating an awakening. Thanks to Ernie Abel, for everything I didn’t learn in
school. My admiration and deepest respect go to Ian Mc Kenzie and John Hopkins for
showing what joy can be found in an in earth and environmental science career.
To all those I had to leave back home: Jay, Julie, Sandeep, Mike, Andrew, Adam,
Kevin, Elan, Damien, Mike, Ange, Rachel, Leslie, Tina, Jeff, Joe, Lorenzo, Graeme,
Rich, Roger, Celine, Chuck & Val, Allyson, Calvin, Kirk & Barb, Bob, Gord, Doug &
Pam, Geoff, Jeff, Darrin, Don, Duane, Chris, Gerry, Chris, Tom, Laurent & Liz, Don
& Karren, Kees and Trent... Aloha.

Here’s to Thomas, Fabio & Bonsai for just about everything one could think of while in
Heidleberg: Friendship, debate, good food, camaraderie, adventure... oh, and thanks
for the T-shirt too.
To the many who’ve helped make this study worth while: Susan, Steffen, Annette,
Clements, Christine, Jorcham, Frauke, Frederika, Francis, Asher, Kirsten, Gaël,
Emmanuel. Ibi, Axel, Birgit, Zbynek, Marta, Fernando, Isabell, Michael, Anja, Jana,
Margarita, Carsten, Jochen, Roswitha, Heiko, Tanja, Iris and Sonja: Danke für akkes.
To Enno and Stephan... Mahalo.
My gratitude to goes to Dale Isler, Istvan Dunkl, Ray Donelick, Richard Ketcham for
sounding analytical questions; Gabriel Gutiérrez-Alonso for forwarding papers and
instilling motivation for discovering the big picture; Uli Glasmacher for guidence
throughout the analysis and interpretation process. I thank Thilo Bechstädt for
facilitating peripherals required to conduct this work and for his expedient review of the
thesis. I am indebted to the Gratuiertenkolleg-273 and the International Postgraduate
Program for their part in funding of research and travel costs associated with the
project. I’d like to thank Günther A. Wagner for allocating the topic and work facility
at the Forschungstelle Archäometrie der Heidelberger Akademie der Wissenschaften
am Max-Planck-Institut für Kernphysik.
Thank-you Anna.
viAbstract
The southern Cantabrian Mountains expose sedimentary rocks having experienced
uplift coeval with alpidic, Variscan and in the south, possibly Cadomian orogenic
cycles; these rocks are commonly referred to by their Variscan tectonic expressions:
the Cantabrian Zone and Narcea Antiform. This thesis yields new experimental and
geologic information from 32 AFT samples gathered along N-directed transects in the
Cantabrian Zone and Narcea Antiform.
The Cantabrian Zone, a nearly complete Palaeozoic succession has been characterised as
the thin-skinned tectonism dominated (Julivert, 1971; Pérez-Estaún et al., 1988), arcuate
foreland fold-and-thrust belt. South of the León Line fault system non-metamorphic
conditions dominate (e.g. Raven & van der Pluijm, 1986; Aller et al., 2005; Keller
& Krumm, 1992; Marschik, 1992; Schneider, 2002; Gasparrini, 2003), to the North
anchizone to epizone conditions are recorded (e.g. Aller et al., 1987, 2005; Marschik,
1992). The Narcea Antiform, unconformably overlain by the Palaeozoic succession,
represents as a Neoproterozoic sedimentary basement, the Variscan foreland-hinterland
transition (e.g. Gutiérrez-Alonso, 1995). Metamorphic conditions increase from
anchizone to greenschist facies (e.g. Aller et al., 1987; Martín-Parra, 1990; Keller &
Krumm, 1992), coincident with hinterland directed increasing deformation.
Unconformable and deformed, discontinuous Stephanian intramontane basin fi lls,
following major structural lineaments (e.g. León Line, Sabero-Gordón and Conombre-
La Urz fault systems) overlay pre-Stephanian successions in both the Narcea Antiform
and Cantabrian Zone. At the foreland-hinterland transition, they record anchizone
to epizone metamorphic signatures (Aller et al., 2005), while those confi ned to the
Cantabrian Zone infer lowest metamorphic grades (e.g. Marschik, 1992; Ayllón et al.,
2003; Frings et al., 2004; Aller et al., 2005).
Experimental results show uranium concentration may be used in the absence of data for
more often observed substitutions to the apatite chemical formula [Ca (PO ) (F,Cl,OH) ]
10 4 6 2
(Elliott, 1994), to predict correlation between AFT grain-ages and their respective D
par
values.
Graphs constructed for AFT central-age versus geographic parameters latitude and
elevation yield negative slopes, indicating a complex elevation dependent cooling
profi le affected by the interplay between differential topography, recent tectonic activity
and time dependent changing geomorphic conditions.
AFT grain-ages from the Narcea Antiform, the Cantabrian Zone and Stephanian basins
reveal thermal conditions coeval with the Variscan orogenic cycle may have been
insignifi cant to totally anneal preexisting fi ssion tracks. AFT grain-age subcomponents
indicate AFT partial annealing zone (PAZ) conditions in the Narcea Antiform may have
prevailed from as early as Neoproterozoic time. Alternatively, many pre-Stephanian
Palaeozoic rocks near major structural lineaments yield AFT-grain-age distributions
completely annealed following Late Carboniferous (late Variscan) time.
Model time-Temperature (t-T) pathways for nineteen of the thirty-two samples
quantitatively estimate the thermal evolution of the southern Cantabrian Mountains.
Samples from the Narcea Antiform yield AFT single-grain-age cooling signatures,
which when evaluated with respect to their 1σ errors, may be interpreted to signal
earliest entry into the AFT-PAZ at Neoproterozoic time, possibly coeval with subduction
along Avalonian-Cadomian-Pan African magmatic arc (Gutiérrez-Alonso et al., 2005).
Pre-Stephanian cooling in Neoproterozoic samples is lowly constrained. Nevertheless
pervasive cooling in these samples occurred coeval with ~ 3.6 km (Veselovsky, 2004;
Dietrich, 2005) of pre-Stephanian Palaeozoic sedimentation in the adjacent Cantabrian
viiBasin. Following a latest Variscan to early post-Variscan thermal pulse to upper-PAZ
conditions the Narcea Antiform experienced denudation related cooling and exited the
PAZ by as early as the Middle Jurassic.
Palaeozoic rocks in the southern Cantabrian Zone evidence middle- to high-PAZ
conditions sustained to between Middle Triassic to Late Jurassic time. Sustained
palaeothermal conditions may be associated with a) heat from a locally derived
sedimentary cover of between 1 km at ~ 85 ˚ C/km (e.g. Frings et al., 2004) transitioning
to that delivered by an assumed ~ 3 - 4 km at 30 ˚C/km, and/or b) the circulation of
thermal convection-heated high salinity brines (cf. Ayllon, 2003; Gasparrini et al., in
press), possibly of Triassic age (cf. Arche & López-Gómez, 1996).
Rapid late Mesozoic cooling to sub-PAZ conditions coeval with the far fi eld onset
of fi rst Atlantic then Biscay rift episode