SPODDS Affiliates Patagonia Trip Guidebook

61 Pages·2009·19.77 MB·English

Deep-Water Deposits of the Cretaceous Cerro Toro and
Tres Pasos Formations, Magallanes Basin,
Chilean Patagonia
Stanford Project on Deep-Water Depositional Systems
(SPODDS)
Fieldtrip Guidebook
March 2-9, 2009
By:
Zane Jobe, Anne Bernhardt, Julie Fosdick, Lisa Stright
Department of Geological and Environmental Sciences
Stanford University
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SCHEDULE
SPODDS in Patagonia 2009

Refer to Maps for location information: Figures 3, 4

Night of 3/2 (M): Gathering in Hosteria Pehoe; introductory remarks

DAY 1 – 3/3 (Tu): Regional tectonics & basin overview; Glacier Grey boat trip
Night of 3/3 (Tu): Hosteria Pehoe

DAY 2 – 3/4 (W): Channel margin architecture, Cerro Toro Formation, Silla
Syncline
Night of 3/4 (W): Hosteria Pehoe

DAY 3 – 3/5 (Th): Channel fill lithofacies and channel stacking, Cerro Toro
Formation, Silla Syncline
Night of 3/5 (Th): Hosteria Mirador del Payne

DAY 4 – 3/6 (Fr): Channel fill sequence and margin architecture, Cerro Toro
Formation, Sierra del Toro
Night of 3/6 (Fr): Hosteria Mirador del Payne

DAY 5 – 3/7 (Sa): Mass transport topography influence on turbidite sandstone
accumulation, Tres Pasos Formation, Sierra Contreras
Night of 3/7 (Sa): Hosteria el Pionero

DAY 6 – 3/8 (Su):
A.M. Growth-faulted, sand-filled mini-basin, Tres Pasos Formation, El Chingue
Bluff
P.M. Channel fill sequences and associated reservoir-scale clastic injections,
Cerro Toro Formation, Lago Sofia
Night of 3/8 (Su): Puerto Natales

Day of 3/9 (M): Drive to Punta Arenas to depart.
SPODDS in Patagonia 2009
Fieldtrip Participant List

SPODDS
Zane Jobe [email protected]
Anne Bernhardt [email protected]
Julie Fosdick [email protected]
Lisa Stright [email protected]

Affiliate Representatives
Jon Schwalbach (Aera Energy)     [email protected]
Sean O’Connor (Aera Energy)     [email protected]
Martin Evans (Anadarko)      [email protected]
Bret Dixon (Anadarko)       [email protected]
Andy Stefaniak (ExxonMobil)     [email protected]
Mark Rosin (ExxonMobil)     [email protected]
Jon Minken (Hess) [email protected]
Nadine Mader (Hess) [email protected]
Erik Scott (Marathon)       [email protected]
Peter McGregor (Repsol YPF) [email protected]
Katarina Borowski (RAG)     [email protected]
Tomas Baldrian (RAG)       [email protected]
Gerhard Wiesmayr (RAG)     [email protected]
Konrad Rockenbauch (RAG)     [email protected]
Waleed Gaber (Shell)       [email protected]
Christopher Werner (Shell)     [email protected]
Ross Abernethy (Shell) ' [email protected]

Fieldtrip guests
Peter King (GNS, New Zealand)    [email protected]
Greg Browne (GNS, New Zealand)   [email protected]

SPODDS Affiliates list
Aera Energy, Anadarko Petroleum Corp., Chevron, ConocoPhillips, Devon Energy, ENI-AGIP,
ExxonMobil, Hess Corp., Husky Energy, Marathon Oil Company, Nexen Energy, Occidental
Petroleum, PetroBras, Reliance Energy, Repsol-YPF, Rohöl-Aufsuchungs AG (R.A.G.), and
Shell
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2009 SPODDS in Patagonia: Field Safety Guide 
Congratulations on your opportunity to participate in this field activity to the Magallanes Basin, southern 
Chile with the SPODDS consortium!  Because this trip will take place solely in the field, this guide 
outlines the associated health and safety issues and serves to inform you of potential hazards that need to 
be considered for your participation. It is important for you to evaluate the stated risks with regard to 
your own personal health and safety, and modify your participation or attendance accordingly. 

EMERGENCY PHONE NUMBERS 
• Mountain Rescue: + (56) 136 
• Ambulance: + (56) 131 
• Hospital: + (56‐61) 411 583 
o Address – Ignacio Carrera Pinto 537, Puerto Natales 
• Clinica Magallanes: + (56‐61) 211 527 
o Address – Baquedano 230, Puerto Natales 
Overview   
Each person is primarily responsible for his/her own safe conduct, as well as contributing to the welfare 
of the entire group. If you are not comfortable participating in any of the particular activities for any 
reason, you are encouraged to notify the Coordinator or other Staff members. There are no negative 
implications for this decision.  If you become uncomfortable with the actions or behavior of your fellow 
participants or the leaders, notify the leader(s).  Actions will be taken to remedy the situation. 
DRIVING 
This is the biggest safety concern during this trip.  We will be driving exclusively on dirt roads, in 
various states of maintenance. 
• SEAT BELT ‐ wear seat belts 
• RADIO ‐ Make sure your radio is on so you can hear directions, geology, etc. 
• DISTANCE, DUST ‐ Keep a safe distance between cars and don’t drive into a dust cloud 
• TIRES, OIL, GAS ‐ Check your tires and fluids daily 

Field Environmental Conditions   
1. Weather: notoriously fickle in the Torres del Paine area ‐ you need to be prepared for 
temperatures from 70F to freezing and all types of precipitation.  It is also VERY WINDY, so stay 
away from cliffs or areas where you may be blown off balance.
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2. Hiking:  The hiking on this trip will be intense.  The terrain is steep and not on trails, containing 
all types of surfaces (rock, scree, mud, etc.).  Elevation gains will be 100 to 500 m and daily 
distances will be up to 10 km.   
a. If at any moment you feel that the hiking is too strenuous, STOP and let one of the 
leaders know.  Drink plenty of water and avoid dehydration, even if it is cold weather.  
Wear appropriate hiking boots and watch your step.  There are trip and fall hazards on 
loose and/or in‐place rocks exist that present trip and fall hazards.  Rain, snow, and hail 
contribute to wet surfaces that can be slippery. 
b. Falling rocks: As with any outcrop, cliff exposures have the danger of falling rocks – stay 
away from cliffs!  Be aware of where people are below you and do not kick rocks down 
on them.  If you are downslope of somebody else, tell them to stop moving until you can 
vacate the danger area. 
3. Wildlife – the only dangerous animal is the mountain lion (puma).  If you encounter one, make 
noise and scare it away.  DO NOT turn around and run away as this mimics its prey.   
4. Flora – many prickly bushes exist, so be mindful of them.  Also, don’t eat any berries that you see 
growing on bushes – some are poisonous. 
5. NO SMOKING – period.  Let me say it again – smoking is not allowed at all on this trip.  With 
the strong drying winds, a fire spreads quickly and has recently (2004) burned about half of the 
park. 

Personal health hazardous conditions 
• Persons taking medication are advised to alert the leader of any special medications they may be 
taking before any emergency situation arises. 
• Persons with known allergies to insect bites, foods, etc. should make such allergies known to the 
leader so that the appropriate actions can be taken in the event of an emergency. 
• Sun block, insect repellant, and proper clothing will be needed to reduce the chance of sunburn, 
insect bites and overexposure. 

GLACIER GREY BOAT HAZARDS 
• Persons susceptible to motion sickness may chose not to take the boat ride, or 
• Anyone who is susceptible to motion sickness should consider mitigation via medicine or 
pressure point devices.    
• The tour boat rocks with the wave, and the possibility exists for trips and stumbles
Table of Contents
Schedule_____________________________________________________________________2
Fieldtrip Participants__________________________________________________________3
Safety Guide _________________________________________________________________4
Contents_____________________________________________________________________6
Fieldtrip overview_____________________________________________________________8
Introduction_______________________________________________________________________8
Geologic Context___________________________________________________________________8
Roadlog__________________________________________________________________________10
References _______________________________________________________________________12
Fig. i.1 – Generalized Cretaceous stratigraphy of the Magallanes Basin_____________________14
Fig. i.2 – Interpretive paleogeography for Cerro Toro Fm________________________________15
Fig. i.3 – Map of Ultima Esperanza District, southern Chile_______________________________16
Fig. i.4 – Landsat image/day-log for trip_______________________________________________17

DAY 1 – Regional Magallanes Basin overview, Cerro Tenerife to Lago Grey ____________________19
Fig. 1.1 – Tectonic map of the Patagonian Andes________________________________________20
Fig. 1.2 – Summary of Rocas Verdes to Magallanes Basin evolution________________________21
Fig. 1.3 – Magallanes Basin stratigraphy ______________________________________________21
Fig. 1.4 – Geologic map and cross section of the Magallanes Basin _________________________22

DAY 2 – Cerro Toro Fm: Silla Syncline, Torres del Paine__________________________________24
Fig. 2.1 – Overview map of Silla Syncline______________________________________________25
Fig. 2.2 – Stratigraphy of the Silla Syncline ____________________________________________26
Fig. 2.3 –Stratigraphic architecture of the Silla Syncline__________________________________27
Fig. 2.4 – Nordenskjold Member, Silla Syncline_________________________________________28
Fig. 2.5 – Cerro Toro style slurry flow deposits _________________________________________29
Fig. 2.6 – Measured section and photos of the Paine Member______________________________30
Fig. 2.7 – Evolution of the Paine Member, Silla Syncline _________________________________31

DAY 3 – Cerro Toro Fm: Pehoe Member, Silla Syncline, Torres del Paine______________________33
Fig. 3.1 – Overview geologic map of Silla Syncline_______________________________________34
Fig. 3.2 – Pehoe Member correlation panel_____________________________________________35
Fig. 3.3 – Pehoe A _________________________________________________________________35
Fig. 3.4 – Pehoe B__________________________________________________________________35
Fig. 3.5 – Pehoe Member schematic evolution __________________________________________35
DAY 4 – Cerro Toro Fm: Sierra del Toro______________________________________________37
Fig. 4.1 – Overview map and photo of Sierra del Toro ___________________________________38
Fig. 4.2 – Wildcat complex axis to margin architecture___________________________________39
Fig. 4.3 – Eastern margin of the Wildcat complex _______________________________________39
Fig. 4.4 – Axial facies of the Wildcat complex___________________________________________39
Fig. 4.5 – Correlation panel of the Wildcat complex axis to margin_________________________40
Fig. 4.6 – Forward seismic model of the Wildcat axis -margin_____________________________41

DAY 5 – Tres Pasos Fm: Sierra Contreras_____________________________________________43
Fig. 5.1 – Overview of the west face of Sierra Contreras__________________________________44
Fig. 5.2 – Tier 1 MTD topography____________________________________________________44
Fig. 5.3 – Tier 2 MTD topography____________________________________________________44
Fig. 5.4 – MTD topography detailed description ________________________________________44
Fig. 5.5 –Model for MTD topography and resultant sandstone architecture__________________44
Fig. 5.6 – Photo and line interpretation of MTD topography ______________________________45
Fig. 5.7 – Forward seismic model of Sierra Contreras____________________________________46

DAY 6A – Tres Pasos Fm: El Chingue Bluff____________________________________________48
Fig. 6A.1 – Overview of El Chingue Bluff______________________________________________49
Fig. 6A.2 – Measured section through ponded slope fan strata_____________________________50
Fig. 6A.3 – Facies of the Tres Pasos Formation _________________________________________51
Fig. 6A.4 – Comparison of minibasin fill with seismic analog______________________________52

DAY 6B – Cerro Toro Fm: Lago Sofia/Cerro Benitez _____________________________________53
Fig. 6B.1 – Photomosaic overview of Loga Sofia injectite complex__________________________54
Fig. 6B.2 – Primary depositional facies overview________________________________________55
Fig. 6B.3 – Intruded facies overview __________________________________________________56
Fig. 6B.4 – Architecture of intrusions _________________________________________________57
Fig. 6B.5 – Comparison of architectural analogs in North Sea basin________________________58
Fig. 6B.6 – Photomosaic overview of Cerro Benitez______________________________________59
Fig. 6B.7 – Channel margin architecture and fill lithofacies_______________________________60
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Deep-Water Deposits of the Cretaceous Cerro Toro
and Tres Pasos Formations, Magallanes Basin,
Chilean Patagonia: Field Trip Guidebook

Prepared for: SPODDS in Patagonia field trip, March 2-9, 2009

By: Zane Jobe, Anne Bernhardt, Julie Fosdick, Lisa Stright
SPODDS consortium, Stanford University
(contact: [email protected])

INTRODUCTION

This field trip is designed to highlight the key facies and stratigraphic architectures that represent the
current state of knowledge of Magallanes basin turbidite systems.
We will spend the first three days investigating outcrops of the Cerro Toro Formation, famous for its
immense conglomeratic channel-fill deposits, and the fourth day looking at the slope deposits of the
overlying Tres Pasos Formation.
With respect to the variety of deep-water features in a single region, these outcrops are second-to-
none. We will examine coarse-grained channel-fill facies, channel-margin relationships and associated
overbank sediments, seismic-scale conglomerate-filled injections, mass-transport topography influence on
turbidite sandstones, and a growth-faulted intraslope mini-basin fill. The SPODDS approach emphasizes
investigation at multiple scales and, as such, we will discuss sedimentation mechanics of individual
sediment gravity flow deposits, distribution and architecture of facies and sedimentary bodies at the sub-
seismic scale, regional stratigraphic relationships, and basin-scale evolution.

GEOLOGIC CONTEXT

Tectonic History and Paleogeographic Setting
The Magallanes foreland basin is an elongate, north-south oriented trough located adjacent to the
Patagonian Andes. The basin has a retro-arc heritage, as an oceanic back-arc basin (Rocas Verde basin)
was first initiated in the region during the latest Jurassic to Early Cretaceous by rifting associated with the
break-up of Gondwana (Dalziel, 1981; Wilson, 1991). Strata of the Jurassic Tobífera Formation,
characterized by volcaniclastic strata and rhyolitic volcanic rocks, as well as thin-bedded shallow marine
sandstone and mudstone of the Zapata Formation, record deposition in the back-arc setting (Wilson, 1991;
Fildani and Hessler, 2005); oceanic crust, formed in association with the development of this basin, is
preserved in the Rocas Verde ophiolite complex, present in the proximal portion of the adjacent fold-
thrust belt (Dalziel, 1974, 1981). Initiation of the Andean Orogeny and associated fold-thrust belt
development spawned the transition from an extensional back-arc to a compressional foreland basin
setting (Wilson, 1991). The onset of turbiditic deposition, represented by the Punta Barrosa Formation,
records this transition (Wilson, 1991; Fildani and Hessler, 2005). Deep-water conditions persisted in the
Ultima Esperanza District region of the Magallanes foreland basin for a period of approximately 15 Ma,
through deposition of the Cerro Toro and Tres Pasos formations (Fig. 1; Natland et al., 1974; Wilson,
1991; Fildani et al., 2003). Upward shallowing in the basin is recorded by deposits of the Dorotea
Formation during the Late Cretaceous and Early Tertiary (Katz, 1963). Tertiary deltaic and fluvial
systems remained active during the early Tertiary further to the east (Malumian et al., 2001).
These foreland basin strata have since been incorporated into the fold-thrust belt and are now
exposed in the foothills of the Andes. Deformation associated with the fold-thrust belt decreases in
intensity eastward. In contrast, the Zapata and Punta Barrosa formations are more highly deformed and,
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on occasion, are isoclinally folded. Cerro Toro Formation exposures are broadly folded and contain
minor reverse faults in some locations. The Tres Pasos Formation is exposed in homoclinally-dipping
cuestas or hogbacks that contain little to no post-depositional faulting/folding. We will see various
outcrops on DAY 1 to serve as an introduction to these formations as well as the basin physiography and
its tectonic evolution. Miocene igneous intrusions, associated with magmatic events that created the
Paine massif, locally disrupt and metamorphose the Upper Cretaceous strata in areas close to the
laccolith. Pleistocene and early Holocene glaciation that sculpted the outcrops and scenery we see today
represents the most recent geologic episode to affect this region.

Cerro Toro Formation
Conglomerate and sandstone of the Cerro Toro Formation crops out in a north-south belt for > 100
km, extending from the Chile-Argentina border in the north, to at least as far south as Cerro Rotonda,
south of Puerto Natales (Fig. 4). Sediment of the Cerro Toro Formation accumulated in a narrow foredeep
constrained by the Andean thrust-front to the west, and the South American craton to the east (Fig. 2;
Wilson, 1991). Upper Cretaceous shallow- and non-marine strata equivalent to the Cerro Toro and Tres
Pasos formations have been identified 60-90 km north of the study area in Argentina; a southward
prograding delta has been interpreted in the area, which supplied sediment into the axial trough of the
deep-marine basin (Macellari et al., 1989). To the south, the basin extends for at least hundreds of
kilometers, as evidenced by conglomerate beds roughly equivalent to those of the Cerro Toro Formation
on Tierra del Fuego (Dott et al., 1982). Coarse-grained sediments were focused within an immense
channel belt that was present along the axis of the Magallanes Basin foredeep. Gravel and sand originated
from the actively uplifting Andean fold-thrust belt to the west (Cecioni, 1957), and was likely transported
to the basin via a series of conduits that cut across the western basin slope (Crane and Lowe, 2008).
We will visit Cerro Toro Formation outcrops at the southern end of the Cordillera Manuel Señoret at
Cerro Benitez/Lago Sofia (Hubbard et al., 2006) on DAY 6. The stratigraphy of the Cerro Toro
Formation at these locations is dominated by a conglomeratic member > 400 m in thickness (the
informally named Lago Sofia Member of Katz, 1963). It is encased in bathyal mudstone (1000-2000 m
paleo-water depth; Natland et al., 1974), and the entire formation has a cumulative thickness of
approximately 2000 m. In addition, we will examine the impressive conglomerate injectite network
(Schmitt, 1991; Hubbard et al., 2006) underlying the main channel-complex at Cerro Benitez on DAY 6.
A comprehensive assessment of the sedimentology and stratigraphic architecture of the Cerro Toro
Formation in the Cordillera Manuel Señoret (Fig. 2) is the focus of Steve Hubbard’s recently completed
Ph.D. research (see references).
The coarse grained channel complexes of the Cerro Toro are also beautifully exposed on Sierra del
Toro, the focus of DAY 4. Numerous channel complexes have been identified and outlined in the 2008
AAPG deepwter atlas. Hubbard et al (2008) provided an overview of the uppermost channel complex
that forms the caprock of the mountain. This informally named ‘Wildcat’ complex is the focus of Zane
Jobe’s Ph.D research. Barton et al (2008) and O’Byrne et al (2008) described the architecture of the
lowermost channel complex on Sierra del Toro, the informally named ‘Condor’ complex. There exists at
least three channel complexes sandwiched in between the upper and lower ones – these will be the focus
of a poster given by Zane Jobe and Anne Bernhardt in the 2007 annual meeting of the AAPG.
The Cerro Toro Formation has been most extensively studied at the Silla Syncline (Fig. 2, 4), where
tectonic folding has resulted in the three-dimensional exposure of channel strata (e.g. Scott, 1966; Winn
and Dott, 1979; De Vries and Lindholm, 1994; Coleman, 2000; Beaubeouef, 2004; Crane, 2004). Results
and conclusions based on research recently completed by SPODDS student, Will Crane, 2004; Crane and
Lowe, 2008), serve as our guide to these exposures on DAY 2 of the field trip. Of particular interest to
turbidite researchers is the relationship of the coarse-grained channel-fill to the finer-grained and thin-
bedded out-of-channel deposits. Some interpret the Silla Syncline as a channel-levee complex
(Beaubouef, 2004) whereas others do not (Crane, 2004). We will investigate and discuss key channel-
margin relationships that address this interpretation. Anne Bernhardt will lead us on DAY 3 to see
outcrops of her PhD thesis, the lower Pehoe member. Here, diverse channel fill lithofacies interfinger and
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channels stack progressively to the south.

Tres Pasos Formation
The Tres Pasos Formation is exposed in a belt parallel to and directly east of the Cerro Toro
Formation (Fig. 4). The Tres Pasos Formation represents the transition from bathyal water depths in the
underlying upper mud-rich portion of the Cerro Toro Formation to the deltaic and shallow-marine strata
of the overlying Dorotea Formation (Smith, 1977). During the latest Cretaceous, deep-water
sedimentation ceased in this area as the delta-slope system migrated south and filled in this deep marine
basin. The Tres Pasos Formation represents the slope component of this prograding depositional system.
Mike Shultz’s (2004) Ph.D. research identified key outcrops and documented the facies and
architectural variability of this slope system. The Tres Pasos Formation is dominated by shale and mud-
rich mass transport complexes punctuated by lenticular sandstone-rich lenses of variable thickness (10-
100 m) and extent (few tens of meters to > 1 km). Brian Romans’ Ph.D. thesis (2007) identified a sandy,
prograding fan-channel system, unfortunately in very inaccessible locations. Dominic Armitage’s Ph.D.
thesis (2009) identified mass transport topography that affects subsequent turbidity currents.
At two of the locations we will visit, facies distribution and sandstone body geometry are directly
influenced by underlying topography, which is a fundamental aspect of slope systems. During the early
part of DAY 6 we will examine a growth-faulted slope mini-basin fill complete with sandstone dikes
parallel to the synthetic and antithetic faults at El Chingue Bluff (Shultz and Hubbard, 2005). Sierra
Contreras, the focus of DAY 5, exposes superb examples of mud-rich mass transport complexes and
sand-rich deposits filling in evacuated slump scars at seismic scale (Shultz et al, 2005; in press). We will
investigate these outcrops both at the seismic scale via photomosaic and at a bed scale where slumps are
exposed near the roadside.

ROADLOG: PUERTO NATALES TO TORRES DEL PAINE

Follow along using the maps provided (Figs. 3, 4). On your journey from Punta Arenas to the
Hosteria Pehoe you need to fill your gas tank in the town of Puerto Natales. There is an Esso station on
the left, a few hundred meters beyond the official entrance to the town across from the bay. The drive
from here to the Hosteria Pehoe is approximately 2 hours. This roadlog (in km) will introduce you the
local geography and some of the geologic features that we will be discussing for the next five days.

0: Set trip odometer at Esso station in Puerto Natales – the body of water here is an inland arm of the
Pacific Ocean called Seno Ultima Esperanza.

8: Airfield – the prominent high ridge to your right is Sierra Dorotea; the vegetated lower slope is the
shale-rich uppermost Tres Pasos Formation and the deltaic Dorotea Formation makes up the cliff-forming
sandstone units at the top.

17: End of pavement – directly in front of you is the backside dip-slope of Cerro Benitez; we will visit
Cerro Toro Formation outcrops on the northern side of this mountain on DAY 6.

22: View of Cerro Mocho (Cerro Toro Formation) to the front-left.

29: View of Jorge Mont (Tres Pasos Formation) ahead and Cerro Mocho (Cerro Toro Formation) again to
the left.

34: Up the valley to the right is the type section of the Tres Pasos Formation.