U.S. Department of the Interior

U.S. Geological Survey

Bulletin 2206–B
The Progreso Basin Province of Northwestern

Peru and Southwestern Ecuador: Neogene and

Cretaceous-Paleogene Total Petroleum Systems

By Debra K. Higley

Bulletin 2206–B

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2004

Version 1.0

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Although this report is in the public domain, permission must be secured from the individual 

copyright owners to reproduce any copyrighted materials contained within this report.

Suggested citation:

Higley, D.K., 2004, The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador: Neogene and 

Cretaceous-Paleogene Total Petroleum Systems: U.S. Geological Survey Bulletin 2206–B, 25 p. 

Available at URL http://pubs.usgs.gov/bul/b2206-b/
iii

Contents

Foreword ........................................................................................................................................................ 1

Abstract .......................................................................................................................................................... 2

Introduction ................................................................................................................................................... 2

Acknowledgments ........................................................................................................................................ 5

Province Geology .......................................................................................................................................... 5

Structural History ................................................................................................................................. 5

Exploration History .............................................................................................................................. 9

Petroleum Occurrence .............................................................................................................................. 12

Hydrocarbon Source Rocks ............................................................................................................. 12

Maturation and Migration ................................................................................................................ 20

Reservoir Rocks ................................................................................................................................. 20

Traps and Seals .................................................................................................................................. 23

Conclusions ................................................................................................................................................. 23

Selected References .................................................................................................................................. 24

Figures

 1. Map of the Progreso Basin province (6083), Ecuador and Peru............................... 3

 2. Stratigraphic units of the Santa Elena block and Tumbes-Progreso subbasins............. 4

 3. Simplified geologic map of the Talara and Progreso Basin provinces and

 surrounding area ............................................................................................................................. 6

 4. Events chart for the Neogene Total Petroleum System (608301) and the Neogene

 Pull-Apart Basin Assessment Unit (60830101) of the Progreso Basin province ................... 7

 5. Events chart for the Cretaceous-Paleogene Total Petroleum System (608302) and

 Assessment Unit (60830201), Santa Elena block of the Progreso Basin province ................ 8

 6. Three main stages (I, II, and III) in the tectonic evolution of the Neogene Tumbes-

 Progreso subbasin within the Dolores-Guayaquil megashear zone ..................................... 10

 7. North-south 2D seismic section of the northeast-oriented normal-faulted stage III

 that is shown as section 5 in figures 1 and 6 ............................................................................ 11

 8–17. Graphs showing:

 8. Mean estimates of size distributions of undiscovered (A) oil and (B) gas fields

 in the Progreso Basin province ............................................................................................ 14

 9. Discovery halves of known oil and gas field sizes for all fields in the

 Progreso Basin province ....................................................................................................... 15

 10. Discovery thirds of known recoverable oil and gas relative to the number

 of fields for the Progreso Basin province based on known recoverable oil

 and gas data from the Petroconsultants database (1996) ............................................... 16

 11. History of field-discovery dates and volumes of known recoverable oil across

 the Progreso Basin province ................................................................................................ 17

 12. Cumulative number of new-field wildcat wells and associated completion

 dates ......................................................................................................................................... 17
iv

 13. Field discovery date in the Progreso Basin province relative to reservoir depths

 in meters (m) ............................................................................................................................ 18

 14. American Petroleum Institute (API) gravity of oil fields in the Talara (6081) and

 Progreso (6083) Basin provinces ......................................................................................... 18

 15. API gravity (degrees) and weight percent sulfur of oils from fields across the

 Progreso (6083) and Talara (6081) Basin provinces, Ecuador and Peru ........................ 19

 16. The relative concentrations of nickel and vanadium in oils from the Progreso

 (6083) and Talara (6081) Basin provinces ............................................................................ 21

 17. Distribution of delta 13C isotopes for saturated and aromatic hydrocarbons,

 Progreso and Talara Basin provinces ................................................................................. 22

Tables

 1. Background statistics for oil and gas fields in the Progreso Basin province (6083),

 Peru and Ecuador ................................................................................................................................ 12

 2. Summary of assessment results for undiscovered resources in the Progreso Basin

 province (1) Neogene Total Petroleum System (TPS) (608301) and Neogene Pull-Apart

 Basin Assessment Unit (AU) (60830101), and (2) the Cretaceous-Tertiary TPS (608302) 

 and Cretaceous-Paleogene Santa Elena Block AU (60830201) ................................................... 13
Foreword

This report was prepared as part of the World Energy 

Project of the U.S. Geological Survey. For this project, the 

world was divided into 8 regions and 937 geologic provinces (Klett and others, 1997). Of these, portions of 128 

geologic provinces were assessed for undiscovered petroleum resources. The petroleum geology of these provinces is 

described in a series of reports like the one presented here. 

The primary documentation for these assessments is contained 

in U.S. Geological Survey World Energy Assessment Team 

(2000). The petroleum geology of these priority and boutique 

provinces is described in the contained series of reports. 

Province names, codes, and boundaries, oil and gas fields, and 

a geologic map of South America are shown in Schenk and 

others (1999).

The purpose of the World Energy Project is to assess 

the volumes of oil, gas, and natural gas liquids that have the 

potential to be added to reserves within the next 30 years. 

These volumes reside in undiscovered fields whose sizes 

exceed the stated minimum-field-size cutoff value for the 

assessment unit or occur as reserve growth of fields already 

discovered. The minimum value is variable, but must be 

at least 1 million barrels of oil equivalent (MMBOE). One 

MMBO is equivalent to 6 billion cubic feet of gas (BCFG). 

Field growth (increase through time of estimated recoverable resources) may result from discovery of new productive 

facies or formations within the field, production of a greater 

percentage of original-oil-in-place through improved secondary or tertiary recovery methods, and perhaps a recalculation 

of reserves that were originally underestimated. Hypothetical 

assessment units are described to explore the potentials of possible new or underevaluated petroleum plays and formations. 

Analogs from other areas of the world are used to determine 

environments of deposition of source and reservoir rocks, to 

describe the burial history of the area, and to assess possible 

reservoir properties of formations within the hypothetical 

assessment unit.

The total petroleum system (TPS) constitutes the basic 

geologic unit of the oil and gas assessment. The TPS includes 

all genetically related petroleum that occurs as shows and 

accumulations (discovered and undiscovered) that (1) have 

been generated by a pod or by closely related pods of mature 

source rock and (2) exist within a limited mappable geologic 

space. This is combined with the other essential mappable 

geologic/geochemical elements (source, reservoir, seal, and 

overburden rocks) that control the fundamental processes of 

generation, expulsion, migration, entrapment, and preservation 

of petroleum (modified from Magoon and Dow, 1994). The 

minimum petroleum system is that part of a total petroleum 

system that encompasses discovered shows and accumulations, along with the geologic space in which the various 

essential elements have been proved by these discoveries.

Graphical depiction of the elements of a total petroleum 

system and contained assessment units is provided in the form 

of events charts that show the times of (1) deposition of essential rock units; (2) trap formation; (3) generation, migration, 

and accumulation of hydrocarbons; and (4) preservation of 

hydrocarbons. 

A numeric code identifies each region, province, total 

petroleum system, and assessment unit; these codes are uniform throughout the project and will identify the same type of 

entity in any of the publications. The codes for the regions and 

provinces are listed in U.S. Geological Survey World Energy 

Assessment Team (2000). The code is as follows: 

• Region, single digit 6

• Province, three numbers to the right of the

region code 6083

• Total Petroleum System, two digits to the 

right of the province code 608301

• Assessment unit, two numbers to the right 

of the petroleum system code 60830101 

Oil and gas reserves quoted in this report are derived 

from Petroconsultantʼs Petroleum Exploration and Production 

database (Petroconsultants, 1996) and other area reports from 

The Progreso Basin Province of Northwestern

Peru and Southwestern Ecuador: Neogene and

Cretaceous-Paleogene Total Petroleum Systems

By Debra K. Higley
2 The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador

Petroconsultants, Inc., unless otherwise noted. Figure 1 

boundaries of the total petroleum systems, assessment units, 

and pods of active source rocks were compiled using geographic information system (GIS) and graphics software. 

Political boundaries and cartographic representations were 

derived, with permission, from Environmental Systems 

Research Instituteʼs ArcWorld 1:3 million digital coverage 

(1992), have no political significance, and are displayed for 

general reference only. Center points of oil and gas fields (fig. 

1) are reproduced, with permission, from Petroconsultants 

(1996). The primary source of geochemical data for this report 

is the GeoMark (1998) database.

Abstract

The Progreso Basin province (6083) in northwestern 

Peru and southwestern Ecuador consists of the Paleogene 

Santa Elena block and Peru Bank, and the Neogene TumbesProgreso subbasin. The Santa Elena block and Peru Bank are 

part of the Cretaceous-Paleogene Total Petroleum System 

(TPS)(608302), which contains the Cretaceous-Paleogene 

Santa Elena Block Assessment Unit (60830201). The TumbesProgreso subbasin includes the Neogene TPS (608301) 

and associated Neogene Pull-Apart Basin Assessment Unit 

(60830101). The complex tectonic history of the Progreso 

Basin province influenced depositional and erosional patterns 

across the region, and also the location, timing, and types of 

seals, traps, possible source and reservoir rocks, and hydrocarbon generation and migration. Marine shales that are interbedded with and overlie reservoir intervals are the probable 

hydrocarbon source rocks. Timing of hydrocarbon generation 

and migration was probably Miocene and younger, following 

creation of the Tumbes-Progreso subbasin by movement along 

the Dolores-Guayaquil megashear. 

More than 220 million barrels of oil (MMBO) and 255 

billion cubic feet of gas (BCFG) have been produced from the 

Progreso Basin province. The means of estimated recoverable 

oil, gas, and natural gas liquids (NGL) resources from undiscovered fields in the province are 237 MMBO, 695 BCFG, 

and 32 MMB NGL, respectively. The means of estimated 

recoverable oil, gas, and NGL resources from undiscovered 

onshore fields are 45 MMBO, 113 BCFG, and 5 MMBNGL, 

and from undiscovered offshore fields are 192 BBO, 582 

BCFG, and 27 MMBNGL. These are USGS grown undiscovered resources that were determined by using a minimum field 

size of 1 million barrels of oil equivalent.

Introduction

The Progreso Basin province is located along the coast of 

northern Peru and southern Ecuador (fig. 1). The province area 

is 47,000 km2 (18,000 mi2) and includes the Neogene TumbesProgreso subbasin and the Paleogene Santa Elena block. 

Included with the Santa Elena block is the Peru Bank, which 

has a similar stratigraphic sequence (fig. 2). The Peru Bank 

is a wedge of Cretaceous-Neogene sediments unconformably overlying the Pennsylvanian Amotape Formation; this 

feature was isolated from the Neogene erosion that removed 

the Paleogene through Cretaceous strata from most of the 

Tumbes-Progreso subbasin. 

Rotational movement along the Guayaquil-Dolores 

megashear zone in Neogene time may have created a trough 

in the Progreso Basin province (Shepherd and Moberly, 

1981)(fig. 1). This trough is the Tumbes-Progreso subbasin, 

a Neogene pull-apart basin that is located between the Talara 

Basin and the Santa Elena block. The Tumbes-Progreso 

subbasin contains Holocene through Oligocene sediments 

unconformably overlying Amotape basement (fig. 2); remnant 

Cretaceous through Eocene formations may be present in areas 

of the subbasin. The Tumbes-Progreso subbasin can be further 

divided into the Tumbes area, which is bounded on the north 

by the northern boundary of the Dolores-Guayaquil megashear 

(fig. 1), and the Progreso area, which has the megashear as 

its southern boundary. They are grouped into one subbasin 

for this study. Progreso and Tumbes are named after towns in 

Ecuador and Peru, respectively. 

The Santa Elena block with its Peru Bank (fig. 1) 

contains the Cretaceous-Paleogene Total Petroleum System 

(TPS)(608302) with its Cretaceous-Paleogene Santa Elena 

Block Assessment Unit (AU)(60830201). The TumbesProgreso subbasin includes the Neogene TPS (608301) and 

Neogene Pull-Apart Basin AU (60830101). The TPS approach 

is used in this report to determine undiscovered recoverable 

oil and gas resources by compiling information about tectonic, 

depositional, and diagenetic factors that control hydrocarbon 

generation, migration, and accumulation in reservoirs, and 

integrating it with exploration and production histories. 

Primary sources of well, field, and geochemical data are the 

Petroconsultants (1996) and GeoMark (1998) databases. 

The Progreso Basin province has a complex structural 

history that includes transcurrent (wrench) faulting as well as 

high- and low-angle faults of various ages (American International Petroleum Corporation [AIPC], no date, “A review of 

the petroleum potential of the Tumbes Basin, Peru”: Denver, 

Colo., 46 p.; Marocco and others, 1995; Zúñiga-Rivero and 

Hay-Roe, 1999). The west boundary of the province is the 

approximate location of the Nazca Plate subduction zone 

under the South American Plate (fig. 1). 

Figure 1 (facing page). The Progreso Basin province (6083), 

Ecuador and Peru. Shown are boundaries of provinces, the 

Neogene Pull-Apart Basin (60830101) Assessment Unit (AU) of 

the Neogene (608301) Total Petroleum System (TPS), and the 

Cretaceous-Paleogene Santa Elena Block (60830201) AU of the 

Cretaceous-Paleogene (608302) TPS. Minimum extent of 60830101 

is approximately 1,000-meter (3,000-foot) water depth. Blue lines 

labeled 3, 4, and 5 are locations of figure 6 cross sections. Map 

projection is Robinson. Central Meridian is 0.
ECUADOR

Lancones Basin

 6082

81° 80°

4°

3°

2°

50

 KILOMETERS

Zorritos 16 West-Central Cordillera

 

6106

Cope

6106

Dolores-Guayaquil  megashear zone

Talara 

Basin

6081

ECUADOR

PERU

Cretaceous-Paleogene 

 Santa Elena Block

Amistad

Albacora

Guayaquil

Chongon-Colonche Cordillera

 PERU

 BANK

 SANTA ELENA 

 BLOCK

Manabi Basin

 6084

Pilar de Zorritos

Ancon

San Pablo 1

La Mata Chivato 1

Pacoa

La Brea Mountains

Borbon Basin

 6085

TPS 608301

TPS 608302

Neogene Pull-Apart Basin Assessment units boundary and name

Boundary between total petroleum systems

Pod of active source rocks boundary;

 tics indicate side of their presence

EXPLANATION

Water

Shoreline

Geologic province boundary and name

Ecuador-Peru boundary

Oil (green) and gas (red) field centerpoints

Minimum extent of 60830101

Dolores-Guayaquil megashear zone

BL Names of geologic structures

3

5

4

Neogene 

Pull- Apart 

Basin

TUMBES-PROGRESO

 SUBBASIN Nazca Plate subduction zone

Introduction 3
4 The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador

Figure 2. Stratigraphic units of the Santa Elena block and Tumbes-Progreso subbasins. Wavy lines and gray 

zones are periods of erosion or nondeposition. Primary reservoirs are marked with green dots. Possible source 

rock intervals are labeled with a small gray box. Modified from Benitez (1990), Gonzales (1999), Jaillard and others 

(1995), Kingston (1994), Kraemer and others (1999), Perupetro (1999), Petroconsultants (1996), and Seranne (1987). 

Jaillard and others (1995) named the Atlanta/Olistrostrome interval the Punta Ancon Formation. Ma, age in millions 

of years.

PERIOD EPOCH SANTA ELENA

Quat. PLEISTOCENE

PLIOCENE

MIOCENE

OLIGOCENE

TERTIARY

EOCENE

PALEOCENE

LOWER UPPER

CRETACEOU

S

PENN

UPPERMAESTRICHTIAN

CAMP-SANT

ATOKAN

CONI-CENO

Tumbes

Cardalitos

Zorritos

Heath

Mancora

Amotape

Atlanta/Olistrostrome

El Rosario

Santa Elena

Azucar

RECENT

Wildflysch

Olistrostrome

Socorro

Santo Tomas

Cayo

Calentura

L. ALB-BERR Pinon

PALEOGENE NEOGENE

MIDDLE

M. 286

66.4

97.5

57.8

52.0

40.0

36.6

23.7

5.3

1.6

Ma

74.5

87.5

TUMBES-PROGRESO

Tablazo

Mal Pelo

Tumbes

Cardalitos

Zorritos

Heath

Mancora

Amotape

La Cruz

Tablazo

Mal Pelo

La Cruz
 The province is also located at the junction of the Dolores-Guayaquil megashear and the Chongon-Colonche fault. 

The Chongon-Colonche fault, also known as the Chanduy 

fault (Ráez Lurquin, 1999), is located along the north boundary of the province and separates it from the Manabi Basin 

and the Chongon-Colonche Cordillera (fig. 1). South of the 

Chongon-Colonche fault, the stratigraphic succession of the 

Santa Elena block is characterized by a thick upper Paleocene 

sequence and by the development of the deeply subsided sedimentary sequence of Neogene age (Zorritos Formation and 

younger strata) in the Progreso Basin province (Jaillard and 

others, 1995)(fig. 2). The Cenozoic deposits of the TumbesProgreso subbasin form at least seven Oligocene to Pleistocene stratigraphic units with a total sedimentary thickness of 

more than 9,000 m (30,000 ft) (Kraemer and others, 2001). 

To the southeast, the La Brea Mountains of the West-Central 

Cordillera separate the Progreso Basin province from the 

Lancones Basin province. The Talara Basin province marks 

the southern boundary of the Progreso Basin province; the 

provinces are segregated by the Dolores-Guayaquil megashear 

zone and the Pilar de Zorritos uplift (fig. 1). 

The figure 3 simplified geologic map of the Progreso 

and Talara Basin provinces and surrounding areas shows oil 

and gas field centerpoints and generalized locations of the 

Amazonas, Dolores-Guayaquil, and Guyana megashears. The 

Dolores-Guayaquil megashear is a regional tectonic wrench 

zone that begins in the offshore area northwest of the Talara 

Basin province and extends along the coast northeastward 

through the Progreso Basin province into Colombia, where it 

is called the Romeral Lineament (AIPC, no date; Kraemer and 

others, 1999). The Dolores-Guayaquil megashear is shown in 

figure 1 as an about 50-km-wide (30 mi) generalized zone of 

faulting because of varying opinions as to its specific boundaries and bordering features. Zúñiga-Rivero and Hay-Roe 

(1999), for example, include the Peru Bank in the Talara Basin 

province. Their location of the Dolores-Guayaquil megashear 

is approximated by the northern boundary of this zone shown 

in figure 1. The AIPC (no date) named the Dolores-Guayaquil 

fault zone at the Pilar de Zorritos the Troncho Mocho fault 

and placed their Dolores-Guayaquil megashear about 65 km 

(40 mi) north of this boundary. Other sources of information include Kraemer and others (1999), Marocco and others 

(1995), Pindell and Tabbutt (1995), Raez Lurquin (1999), and 

Zúñiga-Rivero, Keeling, and Hay-Roe (1998b). 

Acknowledgments

Dan Spancers, a petroleum geologist from Denver, provided essential information on oil and gas fields in Peru and 

Ecuador. This document benefited from reviews by William 

Keefer, Christopher J. Schenk, and Mitchell Henry of the U.S. 

Geological Survey.

Province Geology

Structural History

Offshore Peru and Ecuador contains Cretaceous mid 

oceanic ridge basalt that unconformably overlies a basement 

of metamorphosed sandstones of the Pennsylvanian Amotape Formation (fig. 2). The south coastal area of Ecuador is 

an accreted terrane that is underlain by an oceanic crust that 

formed during the Middle Cretaceous (Aptian-Albian) (Jaillard and others, 1995). The figures 4 and 5 events charts for 

the Neogene (608301) and Cretaceous-Paleogene (608302) 

Total Petroleum Systems show the major structural events 

in the subbasins that formed the petroleum systems, including the times of (1) deposition of source, reservoir, and seal 

formations; (2) development of structural and stratigraphic 

traps; and (3) generation, migration, and accumulation of 

hydrocarbons. Between Late Cretaceous and late Eocene 

time the oceanic-floored allocthonous terranes of southern 

coastal Ecuador underwent a complex geologic evolution that 

included (1) sedimentation in island arc and marginal basin 

settings, (2) plate and intraplate collisions that were associated 

with shear deformation, (3) basin subsidence, and (4) several 

phases of uplift (Jaillard and others, 1995). The tectonic evolution of the Tumbes-Progreso subbasin was controlled by plate 

convergence kinematics during the Cenozoic (Kraemer and 

others, 2001). 

Coastal Ecuador (Tumbes-Progreso subbasin to Colombia) has experienced a 70-degree clockwise rotation since the 

mid-Cretaceous, based on paleomagnetic studies (Roperch and 

others, 1987). Late Cretaceous to middle Paleocene was a time 

of infilling of fluvial to marine sediments in a marginal basin 

(Karig and Moore, 1975). Presence of a thick, coarse-grained 

sequence of Cretaceous (Santonian-Campanian) strata that 

contains low amounts of quartz detritus (Cayo Fm) indicates 

that the sediment source was not a sialic landmass, and that 

the basin was bordered by an island arc that was active at least 

since the Coniacian (about 89.9 to 85.8 m.y.a.) (Jaillard and 

others, 1995). In late Paleocene time, accretion of the Cayo 

remnant arc (located north of the province) to the Andean 

continental margin caused a major deformational phase that 

affected only the southern part of coastal Ecuador. There, 

deformation ended with deposition of overlying thick, coarsegrained, quartz-rich turbidites that infilled an early fore-arc or 

slope basin. A subsequent tectonic event in the early Eocene 

is believed to have resulted in uplift of the entire area (Jaillard 

and others, 1995). Late Paleocene and early Eocene tectonism 

in the Santa Elena block records the most intense episodes of 

deformation with associated gently dipping shear planes, subisoclinal folds, and pervasive cleavage with subsequent tight 

vertical folds and faults; present-day structure of the middle 

Eocene beds displays only reverse faults and gentle folding 

with dips generally less than 30 degrees, which are probably 

due to late Eocene tectonism (Jaillard and others, 1995). 

Province Geology 5
6 The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador

During and following late Eocene time, deformation 

shifted eastward to the Andes Mountains (Jaillard and others, 

1995). This Eocene Incaic orogeny in the Tumbes-Progreso 

subbasin caused right-lateral and rotational movement associated with the northern and southern borders of the DoloresGuayaquil megashear. In the Tumbes-Progreso subbasin, this 

orogeny resulted in intense erosion and denudation of the 

Eocene section (AIPC, no date). Within the Tumbes-Progreso 

subbasin normal faults have a sigmoidal shape with an 

“echelon” arrangement, indicating right-lateral strike-slip 

deformation (Kraemer and others, 2001). 

The Eocene Incaic orogeny resulted in emergence of the 

southern coastline of Ecuador (Santa Elena block) (Jaillard 

and others, 1995), associated erosion of the Cretaceous and 

Paleocene section, mostly in the Tumbes-Progreso subbasin, 

and deposition of many of the reservoir rocks and probably 

also hydrocarbon source rocks in the Progreso Basin province 

(fig. 1). The remaining geosynclinal rocks of the Mesozoic 

island arc sequence in the Tumbes-Progreso subbasin were 

overlain by Eocene molasse sediments that were deformed 

and subsequently overlain by Oligocene and Miocene clastics 

(AIPC, no date). Zúñiga-Rivero, Keeling, and Hay-Roe 

(1998a) indicate that a portion of the southern TumbesProgreso subbasin has Oligocene sediments directly overlying 

Upper Paleozoic strata, although their subbasin boundary is 

Figure 3. Simplified geologic map of the Talara and Progreso Basin provinces and surrounding area. Shown are the 

generalized locations of the Dolores-Guayaquil megashear zone and the Guyana and Amazonas megashears. Geology is 

modified from Schenk and others (1999) 1:5,000,000 scale map of South America.

T

T

MCi

U

J

Q

AD

Cv

J

p�

p�

K

J

T

T

Q

AD T

MCi

Mv

MCi

MCi

Mv

T

K K

K

TrJ

J

Mv

K

PZ

4°

2°

82° 81° 80° 79° 78°

6°

IGNEOUS AND METAMORPHIC ROCKS

SEDIMENTARY ROCKS

Centerpoints of oil and gas fields

Province boundaries

EXPLANATION

Dolores-Guayaquil megashear zone

Guyana megashear

Amazonas megashear

�J

Q Quaternary

T Tertiary

K Cretaceous

J Jurassic

�J 

AD 

Triassic-Jurassic

Precambrian-Devonian

p� 

Cv 

Mv 

MCi

Cretaceous-Tertiary volcanics

Mesozoic volcanics

Mesozoic-Cenozoic intrusives

Precambrian undifferentiated

U Unmapped area Talara

 6081

Sechura

 6080

Progreso

 6083

Manabi

 6084

Trujillo

 6079 Salaverry

 6078

 Lancones

6082

Santiago

 6038
MIGRAT

ACCUM

TRAP F

OVERB

RESERV

SEAL R

SOURC

SY

GEOLOTIME

SCALE

PALEO. EOCENE OLIG. MIOCENE PP

MESOZOIC CENOZOIC

TR TERTIARY

E.M. L. E. M. L. E. L.

JURASSIC CRETACEOUS QUAT.

250 200 150 100 7570 60 50 40 30 20 10 0

GENER

STRUC

Fining and coarsening upward 

42 Ma compress then extension 

Nazca plate

 110-120 Ma MORB

K on Penn (?) basement

86 -

 87 Ma

 57 Ma - northern

 thrust

b a

e e

b,g b,f

b

Heath Zorritos

Mancora, Heath, Zorritos, Cardalitos

c,d

h a

Figure 4. Events chart for the Neogene Total Petroleum System (608301) and the Neogene Pull-Apart Basin Assessment Unit (60830101) of the ProDark gray and blue shading mark the time intervals of primary events. Oceanic crust formed during the Aptian-Albian (Jaillard and others, 1995). Mmidoceanic ridge basalt on Pennsylvanian (Penn) basement rocks. Eocene (42 Ma) compressional tectonism of the Andes was followed in Oligocthe Farallon Plate into the Cocos and Nazca Plates (Handschumacher, 1976; Marocco and others, 1995; Pilger, 1984). Events include (1) Santa Elen(Santa Elena Formation) to upper Eocene (Socorro Formation and Wildflysch Olistrostrome) and Quaternary Tablazo Formation, and (2) Tumbes-Prmiddle Miocene Zorritos, Heath, and Cardalitos (Subibaja) Formations. There is no documented information on hydrocarbon source rocks or on thmigration. Time periods of unconformities (wavy black lines) were determined from American International Petroleum Corporation (no date), GonzKraemer and others (1999), Perupetro (1999), Petroconsultants (1996), and Seranne (1987). Letter codes refer to references: a, Baldock (1982) and Eb, Jaillard and others (1995); c, GeoMark (1998); d, Petroconsultants (1996); e, Zúñiga-Rivero, Keeling, and Hay-Roe (1998a); f, Pindell and Tabbutt (Moberly (1981); and h, Haq and others (1987).
MIGRAT

ACCUM

TRAP F

OVERB

RESERV

SEAL R

SOURC

SY

GEOLOTIME SCALE PALEO. EOCENE OLIG. MIOCENE PP MESOZOIC CENOZOIC TR TERTIARY E.M. L. E. M. L. E. L. JURASSIC CRETACEOUS QUAT. 250 200 150 100 7570 60 50 40 30 20 10 0 GENER

STRUCT

42 Ma compress. then extension Nazca plate 110-120 Ma MORB K on Penn (?) basement 86 - 87 Ma 57 Ma -northern thrust lower Eocene hiatus a Santa Elena d Azucar Atlanta/Olistrostrome Santo Tomas Calentura b c b,g b,f bb Cayo El Ros. WO Socorro Tablazo aa a e Figure 5. Events chart for the Cretaceous-Paleogene Total Petroleum System (608302) and Assessment Unit (60830201), Santa Elena block of the P

Dark gray and blue mark the time sequences of primary events. Oceanic crust formed during the Aptian-Albian (Jaillard and others, 1995). MORB oceanic ridge basalt on Pennsylvanian (Penn) age basement rocks. Eocene (42 Ma) compressional tectonism of the Andes was followed in OligocFarallon Plate into the Cocos and Nazca Plates (Handschumacher, 1976; Marocco and others, 1995; Pilger, 1984). Events include (1) Santa Elena blElena Formation) to late Eocene (Socorro Formation and Wildflysch Olistrostrome [WO]) and Quaternary Tablazo Formation, and (2) Tumbes-ProgreMiocene Zorritos, Heath, and Cardalitos (Subibaja) Formations. Time periods of unconformities (wavy black lines) were determined from AmericaCorporation (no date), Gonzales (1999), Kingston (1994), Kraemer and others (1999), Perupetro (1999), Petroconsultants (1996), and Seranne (1987). following references: a, Kingston (1994); b, Jaillard and others (1995); c, GeoMark (1998); d, Petroconsultants (1996); e, Haq and others (1987); f, Ping, Shepherd and Moberly (1981).
the northern limit of the Dolores-Guayaquil megashear in 

figure 1. 

AIPC (no date) determined that a gravity minimum lies 

along and landward of the western terminus of the DoloresGuayaquil megashear zone (fig. 1); high-angle complex fault 

zones were inferred from the linear alignments of gravity data, 

combined with 2D seismic reflection data in the offshore area, 

and by surface geologic evidence in the onshore area east of 

the Zorritos field. The gravity anomalies appear to be splays 

off the Dolores-Guayaquil megashear and they outline the 

bifurcation of the Tumbes-Progreso subbasin around the Peru 

Bank (AIPC, no date).

Intermontane basins began to form in late Oligocene time 

with reactivation of Andean tectonism, and movement ceased 

in the latest Miocene (about 7 m.y.a.) (Marocco and others, 

1995). Kraemer and others (1999, 2001) identified three main 

tectonostratigraphic stages from Oligocene to the present that 

are separated by regional unconformities and at least eight 

sequences, as identified on eight 2D seismic lines. The following interpretations are from (1) Kraemer and others (1999, 

2001) analysis of 800 km (500 mi) of marine 2D seismic data 

and on records from 18 exploratory wells (figs. 6, 7), and (2) 

the AIPC (American International Petroleum Corporation, no 

date) analysis of 1,850 km (1,150 mi) of 2D seismic. 

1. The initial tectonic stage (late Oligocene-early Miocene) (fig. 6, stage I) corresponds to the deposition 

of fluvial and marine deposits of Mancora, Heath, 

and Zorritos sequences in a narrow unstable platform that was open to the northwest. Peneplanation 

of the Heath Formation was followed by deposition 

of the Zorritos Formation and then by a period of 

block faulting (AIPC, no date). Late Oligocene-early 

Miocene was the time of separation of the Nazca 

Plate from the South American Plate with active subduction at the Peru-Chile trench and creation of the 

Neogene (Tumbes-Progreso) fore-arc basins (Jaillard 

and others, 1995) and deposition of the thick 

Miocene section that forms the reservoir and associated probable source-rock intervals in the TumbesProgreso subbasin (fig. 2). Miocene sediments 

thicken rapidly to the west across the Pilar de 

Zorritos (AIPC, no date).

2. The second tectonic stage (middle to late Miocene) 

(fig. 6, stage II) began with a regional drop in relative 

sea level and associated deep erosion of the former 

platform; valleys were subsequently filled and covered by the marginal marine and deltaic sediments 

of the Cardalitos, Tumbes, and Mal Pelo sequences. 

During this stage, an episode of open folding produced a general tilting of these deposits toward the 

north-northwest. The middle Miocene is also associated with block faulting across the Progreso and 

Talara Basin provinces and renewed uplift of the 

Andes Mountains (AIPC, no date). Upper Miocene 

sediments were deposited during a relative sea-level 

rise, until the paleotopography was completely 

buried.

3. The third tectonic stage (Pliocene to Present) (fig. 

6, stage III; fig. 7) began with the onset of normal 

faults that dip to the northwest, and the deposition 

of Mal Pelo and La Cruz sequences that are covered 

by Holocene deposits of the Tablazo Formation. 

Included are formation of horst and graben structures and gravity- and basement-involved faulting, 

mostly in the Tumbes-Progreso subbasin (AIPC, no 

date). Normal faulting remained active during the 

Pleistocene and is still active, as evidenced by recent 

deformation of sea-floor sediments.

Exploration History

Centerpoints of oil and gas fields in the Progreso Basin 

province are shown in figure 1. Fewer than 100 wildcat wells 

were drilled in Ecuador or Peru during 1980 to 1990; average 

success ratio for producing wells was 60 percent for Ecuador 

and 30 percent for Peru (Kronman and others, 1995). The 

Petroconsultants (1996) database lists cumulative production 

data for 13 of the 19 Progreso Basin province oil and (or) gas 

fields, but only limited data for the other 6, which have discovery dates of 1956 to 1991. Six of the 19 fields are located 

in the Tumbes-Progreso subbasin, and 13 are in the Santa 

Elena block. Reported production is commonly commingled 

for several Tertiary units in the Tumbes-Progreso subbasin 

and for both Tertiary and Cretaceous formations in the Santa 

Elena block. Because there are limited data for a number of 

wells in the database, the statistics given herein should be 

taken as minimum production volumes and estimated recoverable resources. Background statistics for oil and gas fields are 

listed in table 1.

More than 220 million barrels of oil (MMBO) and 255 

billion cubic feet of gas (BCFG) have been produced from 

the Progreso Basin province. Ranges in field-size distribution 

listed in table 2 show the U.S. Geological Survey estimates for 

undiscovered oil, gas, and natural gas liquids resources for the 

province that have the potential to be added to reserves within 

the next 30 years (USGS World Energy Assessment Team, 

2000). The mean estimated oil, gas, and natural gas liquids 

resources in undiscovered fields are 237 MMBO, 695 BCFG, 

and 32 MMB of NGL, respectively (table 2). Mean estimated 

recoverable oil, gas, and NGL resources in undiscovered 

onshore fields are 45 MMBO, 113 BCFG, and 5 MMBNGL; 

undiscovered offshore recoverable resources are 192 BBO, 

582 BCFG, and 27 MMBNGL. Minimum size of fields that 

were used in this analysis is 1 MMBO and (or) 6 BCFG. 

Figure 8 shows the proposed frequency distribution of undiscovered oil (A) and gas (B) fields within the Progreso Basin 

province. The mean estimate is 26 undiscovered oil fields and 

14 undiscovered gas fields. Size distributions show few large 

undiscovered oil or gas fields; estimates include only one 

undiscovered oil field containing as much as or more than 32 

Province Geology 9
10 The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador

MMBO, and also only one gas field containing as much as or 

more than 96 BCFG. Number of undiscovered fields increases 

as the field size decreases; estimates are for about 6 undiscovered oil fields in the 1 to 2 MMBO size and 4.5 gas fields in 

the 6 to 12 BCFG range. 

Figure 9 shows field-size distribution based on periods 

of discovery for known recoverable volumes in current oil 

fields, compared to the number of fields in each size range. 

Discovery history curves in mature basins commonly show the 

largest fields are discovered early in the history of exploration 

I

II

III

South North

Section 4

Section 3

Section 5

Holocene

La Cruz sequence

Cardalitos, Tumbes sequences

Zorritos sequence

Heath sequence

Mancora sequence

Basement

EXPLANATION

Figure 6. Three main stages (I, II, and III) in the tectonic evolution of the Neogene Tumbes-Progreso subbasin 

within the Dolores-Guayaquil megashear zone (modified from Kraemer and others, 1999, reprinted by permission 

from the primary author, 06/19/02). Approximate locations of sections 3, 4, and 5 are shown in figure 1. The 2D 

seismic section of this reconstruction is shown in figure 7.
and field size tends to decrease through time. In this case, the 

largest is the Ancon field in the Santa Elena block, discovered 

in 1921. Recoverable oil and gas resources for this field are 

134 MMBO and 167 BCFG. There are only eight fields that 

have known or grown recoverable resources of 1 MMBOE or 

greater. Known recoverable oil and gas in the province is 374 

MMBOE for current oil and gas fields that have a minimum 

known recoverable of 1 MMBOE. The curve of known recoverable compared to number of fields (fig. 10) shows a slightly 

more symmetrical shape, mainly because the Petroconsultants 

database lists 11 fields that exhibit known recoverable oil and 

gas resources of 1 MMBOE or greater. The distribution of 

known recoverable oil (1 MMBO and greater) relative to the 

discovery year is shown in figure 11. The Zorritos field was 

discovered in 1863 and produced more than 3.7 MMBO from 

the Heath Formation by the 1965 shut-in date (Pardo and 

Pisconte, 2002). This discovery was followed by the Santa 

Paula (1919) and Ancon (1921) fields. Cumulative number of 

new-field wildcat wells compared to the drilling completion 

year (fig. 12) shows a flat linear trend for the Zorritos discovery and a gradual upward climb beginning with the Santa 

Paula and Ancon discoveries and continuing to the 1996 database date. Drilling depth would appear to have no appreciable 

effect on the intensity of later exploration (fig. 13) because 

maximum drill depth is 2,896 m (9,500 ft) and median depth is 

shallow at 448 m (1,470 ft)(table 1).

The mean estimated undiscovered resources for the Santa 

Elena block are 200 MMBO, 224 BCFG, and 11 MMBNGL 

for the Cretaceous-Paleogene TPS (608302). Production 

from the Neogene TPS (608301) is primarily from Miocene 

Figure 7. North-south 2D seismic section of the northeast-oriented normal-faulted stage III that is shown as section 5 in figures 

1 and 6 (modified from Kraemer and others, 1999, reprinted by permission from primary author, 06/19/02). Growth sediments of 

the Mal Pelo and La Cruz sequences are covered by Holocene strata that also exhibit deposition that is concurrent with fault 

movement, which is still occurring over areas of the basin.

Province Geology 11

 Zorritos

 Sequence

 Zorritos

 Sequen

 Zorritos ce

 Sequence

 Zorritos

 Sequence

 La Cruz

 Sequence

 La Cruz

 Sequence

 Mal Pelo Mal Pelo Sequence

 0

 500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

5,500

6,000

N 1,537 m

97 tr/cm 1.0 IPS

Z-20

S

1,200 1,250 1,300 1,350 1,400 1,450 1,500 1,550 1,600 1,650 1,700 1,750 1,800 1,850 1,9

Z

Z-45

-41

Z-24

Z-30

Z-32

FEET

 Holocene

 Holocene Holocene
12 The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador

sandstones in the Tumbes-Progreso subbasin; the mean 

estimated undiscovered recoverable resources (table 2) are 37 

MMBO, 471 BCFG, and 21 MMBNGL (USGS World Energy 

Assessment Team, 2000). Travis and others (1976) estimated 

offshore-undiscovered resources of 335 MMBO for this 

Neogene Pull-Apart Basin AU (60830101). In the TumbesProgreso subbasin of the Neogene TPS Albacora field, 

cumulative production is approximately 100 MMBO and 107 

MMCF gas, and 4 MMBO was produced from the Zorritos 

field during its 102-year life (Perupetro, 1999). Although 

gas hydrate resources were not assessed as part of this study, 

offshore Ecuador and Peru exhibit excellent potential for these 

resources (Miller and others, 1991). 

Petroleum Occurrence

Hydrocarbon Source Rocks

There is little published geochemical information on 

shales and (or) limestones that could serve as potential hydrocarbon source rocks in the Talara or Progreso Basin provinces. 

The probable hydrocarbon source rocks for the Progreso Basin 

province (fig. 2) are Cretaceous and Tertiary marine shales 

that are interbedded with and overlie the reservoir intervals. 

Statistics on oils were compiled using the GeoMark (1998) 

and Petroconsultants (1996) databases. 

The following geochemical evidence from oils indicates 

that Tertiary marine shales are the probable hydrocarbon 

source rocks for the Tumbes-Progreso subbasin and the Santa 

Elena block. A potential source rock for the Santa Elena block 

is marine shales of the mid-Cretaceous Calentura Formation 

(fig. 2), which is composed of a 200-m-thick (660 ft) succession of shales, black laminated limestones, and thin-bedded 

turbidites that were deposited in a sediment-starved, deepmarine pelagic environment (Jaillard and others, 1995). These 

Calentura strata are located in the area of Guayaquil and the 

Chongon-Colonche Cordillera (fig. 1)(Jaillard and others, 

1995). 

Probable source rocks in the Tumbes-Progreso subbasin 

are the upper Oligocene to possibly lower Miocene Heath Formation and the Miocene Cardalitos Formation (Zuñiga-Rivero 

and others, 1998a); Kraemer and others (2001) believe the 

Heath Formation to be the primary source rock. Sanz (1988) 

also speculated that deep marine shales that are interbedded 

with Heath Formation turbidite sandstones are the source of 

oil in the Zorritos and Cope fields, southern Tumbes-Progreso 

subbasin (fig. 1). He does not present geochemical evidence 

to support this opinion, which is based on analysis of well and 

outcrop samples. Marine shales within the Heath and Cardalitos Formations are likely source rocks in the Santa Elena 

block.

Sulfur concentrations for two probable Tertiary oils in the 

Santa Elena block range from 0.05 percent to 0.5 percent, with 

a median of 0.26 percent (table 1) (GeoMark, 1998). Sulfur 

percentages and API gravity of oils are influenced by migration history, biodegradation, evaporation of oils, and other 

geologic and geochemical factors. Biodegradation can result 

in an increase in sulfur as the microorganisms preferentially 

metabolize light-chain hydrocarbons with lower percentages 

of sulfur. Resulting oils therefore tend to have lower API 

gravities and greater sulfur concentrations. Many of the 

Table 1. Background statistics for oil and gas fields in the Progreso Basin province (6083), Peru and Ecuador. 

[Reported production is commonly commingled for several Tertiary stratigraphic units. Cumulative production for 12 of the 19 oil and (or) gas 

fields is listed in the 1996 Petroconsultants database. The oil column includes both oil and oil and gas fields. The number (n) of data points follows each column. Table abbreviations: million barrels of oil equivalent (MMBOE); estimated ultimate recoverable oil and gas (EUR); cumulative (CUM); and cubic feet of gas per barrel of oil (CFG/BO). Sources of data are the Petroconsultants (1996) and GeoMark (1998) databases.]

 

 Fields with 1 MMBOE EUR and greater 9 2

 Fields with 1 MMBOE CUM and greater 5 0

 Years of production 1863–1995 1970–1992 

 Median gas-oil ratio (CFG/BO) 577 5

 Ranges of gas-oil ratio (CFG/BO) 454–1,000 5

 Median API gravity (degrees) 34 28

 Range in API gravity of oils 18–48 28

 Median percentage of sulfur in oils 0.26 4

 Range of sulfur in oils (percent) 0.05–0.5 4

 Median net perforated thickness–meters and (feet) 15 (49) 5 

 Maximum net perforated thickness–meters and (feet) 36 (118) 5 122 (400) 1

 Median depths of drilling–meters and (feet) 448 (1,470) 16 

 Maximum depths of drilling–meters and (feet) 2,896 (9,500) 16 2,505 (8,220) 2

 Range of water depths–meters and (feet) 32–64 (105–210) 2 37–102 (121–335) 2 

 Range of porosity (percent) 11–24 3 14.8–17 2

Oil fields n Gas fields n
Code Undiscovered Resources

and Field MFS Prob. Oil (MMBO)

Type (0-1) F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 

Gas (BCFG) NGL 

608301 Neogene Total Petroleum System60830101

Oil Fields 1 1 4 15 5 0 2 10 3 0 0 

Gas Fields 6 7 52 169 65 0 2 

Total 1.00 1 4 15 5 7 54 179 68 0 2 

60830101

Oil Fields 1 4 23 90 32 2 14 58 20 0 1 

Gas Fields 6 41 305 996 383 2 1

Total 1.00 4 23 90 32 43 319 1,054 403 2 14 

608302 Cretaceous-Paleogene Total Petroleum System60830201

Oil Fields 1 9 36 86 40 5 21 56 25 0 1 

Gas Fields 6 4 15 51 20 0 1 

Total 1.00 9 36 86 40 9 37 107 45 0 2 

60830201 Cretaceous-Paleogene Santa Elena Block Assessment Unit (80 percent of undiscovered oil fields and 80 pe

Oil Fields 1 35 142 343 160 20 86 224 99 1 5 

Gas Fields 6 17 60 206 80 1 3 

Total 1.00 35 142 343 160 38 146 430 179 2 8 

1.00

Neogene Pull-Apart Basin Assessment Unit (14.5 percent of undiscovered oil fields and 14.5 percent of undiscovered gas fields allocated to ONSHORE province 6083)

Neogene Pull-Apart Basin Assessment Unit (85.5 percent of undiscovered oil fields and 85.5 percent of undiscovered gas fields allocated to OFFSHORE province 6083)

Cretaceous-Paleogene Santa Elena Block Assessment Unit (20 percent of undiscovered oil fields and  20 percent of undiscovered gas fields allocated to ONSHORE province 6083)

undiscovered gas fields allocated to OFFSHORE province 6083)

1.001.001.00

Table 2. Summary of assessment results for undiscovered resources in the Progreso Basin province (1) Neogene Total Petroleum System (TPS)(608301) and Neogene Pull(AU)(60830101), and (2) the Cretaceous-Tertiary TPS (608302) and Cretaceous-Paleogene Santa Elena Block AU (60830201)(World Energy Assessment Team, 2000). [Catego

(MMBO); billion cubic feet of gas (BCFG); million barrels of natural gas liquids (MMBNGL); minimum field size assessed (MFS in MMBO or BCFG); and probability (Prob.), inaccessibility probabilities of at least one field equal to or greater than the MFS. Results shown are fully risked estimates. All liquids in gas fields are included under the ncategory. F95 represents a 95-percent chance of at least the amount tabulated. Other fractiles are similarly defined. Fractiles are additive under the assumption of perfec

indicates not applicable.] 
14 The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador

Figure 8. Mean estimates of size distributions of undiscovered (A) oil and (B) gas fields in the Progreso Basin province. 

Distributions are based on grown oil and gas assessments. MMBO, million barrels of oil; BCFG, billion cubic feet of gas.

0

1

2

3

4

5

6

7

8

1 to <2 2 to <4 4 to <8 8 to <16 16 to <32 32 to <64 64 to <128 128 to <256 256 to <512 512 to 

<1,024

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

6 to <12 12 to <24 24 to 48 48 to <96 96 to <192 192 to <384 384 to <768 768 to 

<1,536

1,536 to 

<3,072

OIL-FIELD SIZE (MMBO)

UNDISCOVERED OIL FIELDS (No.)

Minimum field size: 1 MMBO

Mean number of

undiscovered fields: 26

GAS-FIELD SIZE (BCFG)

UNDISCOVERED GAS FIELDS (No.) 

Minimum field size: 6 BCFG

Mean number of

undiscovered fields: 14

A

B
Tertiary oils in the Progreso and Talara Basin provinces, 

particularly those with API gravity less than 23° (fig. 14), 

exhibit some early biodegradation; these commonly have 

a second phase of nonbiodegraded to slightly biodegraded 

hydrocarbons. 

Most oils of the Progreso Basin province are in the range 

of light to medium API gravity; the median is 34°. Biodegradation has caused some of the scatter in figure 15, which shows 

the ratio of API gravity of oils to the weight percent of sulfur. 

The Tertiary oils of the Talara Basin province and the Santa 

Elena block of the Progreso Basin province are generated from 

a probable Tertiary source rock or range of Tertiary source 

rocks. The oil sample shown for the Pennsylvanian Amotape 

Formation of the Talara Basin province is also grouped within 

the Tertiary oils. This Amotape oil sample may include 

Tertiary oils since production is reported commingled for 

Pennsylvanian, Cretaceous, and Eocene reservoirs at this 

location. Amotape Formation reservoir rocks are mostly 

quartzite, and any associated Paleozoic shales would probably 

be overmature for hydrocarbon generation.

The percentages of nickel and vanadium in oil can be 

influenced by depositional environment (marine as opposed to 

0

1

2

3

NUMBER OF FIELDS

Second one-half of fields discovered

First one-half of fields discovered

1 to <2

2 to <4

4 to <8

8 to <16 

16 to <32 32 to <64 

256 to <512

512 to <1,024

128 to <256

64 to <128

KNOWN OIL FIELD SIZE (MMBOE)

Figure 9. Discovery halves of known oil and gas field sizes for all fields in the Progreso Basin 

province. Generally, the largest fields are discovered early in the history of exploration and field sizes 

decrease through time. Although Ancon, the largest oil field, was discovered in 1921, this trend is 

less apparent in this frontier basin because there are only a few fields. MMBOE, million barrels of oil 

equivalent.

Petroleum Occurrence 15
16 The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador

nonmarine), shale as opposed to carbonate source rocks, 

biodegradation, migration history, and other factors that 

remove lighter chain hydrocarbons and tend to concentrate 

metallic elements in the longer chain atoms, onto which these 

elements are preferentially attached. However, the ratio of 

nickel to vanadium in oils is stable through time. Because 

nickel and vanadium atoms exhibit similar chemical properties, they and the hydrocarbon molecules that contain them are 

generally influenced similarly through their burial history. 

Scatter in data in the nickel-vanadium charts (fig. 16) 

for the Progreso and Talara Basin provinces results primarily 

from the oils having different source rocks. Geochemical data 

reported by GeoMark (1998) on two oils from the Santa Elena 

block of the Progreso Basin province were from the Ancon 

and Ecud fields; although the oil source was unidentified, the 

possible reservoir is the Eocene Santo Tomas Formation. Gas 

chromatograms of the oils indicate a minor loss of light chain 

hydrocarbons and show only minor evidence of later pulses of 

migration. 

The probable Tertiary oils of the Progreso Basin province 

are grouped with Tertiary oils of the Talara Basin province 

(fig. 16). Talara Basin province samples are generally less 

than or equal to 10 parts per million (ppm) nickel and 30 ppm 

vanadium; one sample from a Paleocene reservoir contains 

about 7 ppm nickel and almost 60 ppm vanadium. The one 

Pennsylvanian Amotape oil is characteristic of a Tertiary 

source. Visual examination of groups of oil samples in figure 

16 could indicate different sets of source rocks, but this is 

misleading. Each “group” of three or more samples is a mix 

of Eocene and Paleocene oils, as opposed to their being 

NUMBER OF FIELDS

KNOWN RECOVERABLE OIL AND GAS (MMBOE)

1 to <2

2 to <4

4 to <8

8 to <16 

16 to <32

32 to <64 

128 to <256

64 to <128 

<1

8

7

6

5

4

3

2

1

0

Third one-third of fields discovered

Second one-third of fields discovered

First one-third of fields discovered

Figure 10. Discovery thirds of known recoverable oil and gas relative to the number of fields for the Progreso Basin 

province based on known recoverable oil and gas data from the Petroconsultants database (1996). Data were divided into 

the first, second, and third one-thirds of discovered fields. MMBOE, million barrels of oil equivalent.
1

10

100

1,000

1860 1880 1900 1920 1940 1960 1980 2000

FIELD-DISCOVERY YEAR

KNOWN OIL-FIELD SIZE (MMBO)

0

10

20

30

40

50

60

70

80

90

100

1860 1880 1900 1920 1940 1960 1980 2000

DRILLING-COMPLETION YEAR

CUMULATIVE NEW-FIELD WILDCAT WELL

S

Figure 11. History of field-discovery dates and volumes of known recoverable oil across the Progreso Basin province. Sharp 

increases in the volume of recoverable hydrocarbons generally indicate a major field discovery or combined effects of numerous field discoveries. Production in this basin is too scattered for clear trends, aside from discovery in the early 1990s of fields 

such as Pacoa, San Pablo 1, and La Mata Chivato 1 (fig. 1). Minimum field size is 1 million barrels of oil (MMBO) recoverable.

Figure 12. Cumulative number of new-field wildcat wells and associated completion dates (from Petroconsultants, 1996). 

Petroleum Occurrence 17
18 The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador

0

500

1,000

1,500

2,000

2,500

3,000

1860 1880 1900 1920 1940 1960 1980 2000

FIELD-DISCOVERY YEAR

RESERVOIR DEPTH, OIL FIELDS (M)

Figure 13. Field discovery date in the Progreso Basin province relative to reservoir depths in meters (m). 

Figure 14. American Petroleum Institute (API) gravity of oil fields in the Talara (6081) and Progreso (6083) Basin provinces. Light oil 

is commonly characterized by an API of 31° to 55°, medium grade oil by 22° to 31°, and heavy oil by less than 30°.

Talara Basin median API=32°

 for 36 samples

Progreso Basin median API=34°

 for 28 samples

API GRAVITY (DEGREES)

NUMBER OF OIL FIELDS

10

8

6

4

2

0

10 to <15 15 to <20 20 to <25 25 to <30 30 to <35 35 to <40 40 to <45 45 to 50
segregated by formation. Distribution of data suggests that 

the Tertiary and unknown oils were from Tertiary source 

rocks that were deposited in similar environments, such as all 

were marine shales. A probable exception to this is the three 

oil samples that contain greater than 25 ppm nickel (fig. 16 

A, B). Although these oils are from an unknown but probable 

Tertiary source, they have vanadium concentrations that are 

similar to other Tertiary oils, whereas the nickel content is 

much greater at 27 to 31 ppm. This may be due to differences 

in depositional environment. These oils could have been 

generated from nonmarine or mixed marine-nonmarine shale 

that contained a greater initial ratio of nickel to vanadium. 

Gas chromatograms of these three oils show an early stage 

of extensive biodegradation followed by a second pulse of 

migration of hydrocarbons into the reservoir. These secondary 

hydrocarbons show minor to extensive biodegradation, as 

indicated by concentration of heavier chain hydrocarbons 

relative to lighter ones. Biodegradation has little influence on 

the relative concentrations of nickel to vanadium. Mixing of 

oils from several source rocks may also have influenced the 

nickel and vanadium contents of other oils. 

The 13Cdistribution of saturated and aromatic hydrocarbons from oils across the Progreso and Talara Basin provinces 

is shown in figure 17. The Talara and Progreso Basins contain 

one group of Tertiary and Pennsylvanian reservoirs. The 

formations that produced the two Progreso Basin oils shown 

in figure 17 were unidentified but are probably Eocene in age 

based on grouping with other oils and on producing formations in the sampled wells. The 20 Talara Basin oil samples are 

primarily from the Eocene Talara, Parinas, and Chacra Sandstones, and the Mogollon and Basal Sandstones of the Salina 

Group. One Talara Basin oil sample is listed in the GeoMark 

database as being from the Pennsylvanian Amotape Formation in the Portachuelo field. Grouping of this one sample with 

SULFUR (WEIGHT %)

API GRAVITY (DEGREES)

0.4

0.3

0.2

0.1

0

15 20 25 30 35

Pennsylvanian formations

Tertiary reservoirs

Unknown reservoir ages

Progreso Basin samples

Figure 15. API gravity (degrees) and weight percent sulfur of oils from fields across the Progreso (6083)(red circles) and 

Talara (6081) Basin provinces, Ecuador and Peru. Based on the distribution of data and other factors, there is one sample 

population for the provinces with a probable Tertiary source rock or set of source rocks. Scatter in data results partly 

from analytical methods and from biodegradation of oils from Tertiary reservoirs. Three Tertiary oils that exhibit biodegradation are shown in green.

Petroleum Occurrence 19
20 The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador

the other mostly Eocene samples is indicative of a common 

Tertiary source. 

Maturation and Migration

Paleozoic through Tertiary source rocks across Colombia, 

Ecuador, and Peru became thermally mature for oil generation 

during Neogene phases of basin development (Pindell and 

Tabbutt, 1995). The probable timing of source-rock maturation for Tertiary and older reservoirs is Miocene and younger 

across the basin (figs. 4, 5)(Jaillard and others, 1995; Pindell 

and Tabbutt, 1995). However, Kingston (1994) believed that 

possible source rocks would have been thermally mature by at 

least late Eocene time in the Santa Elena block of the Progreso 

Basin province, even given the low heat gradient expected in a 

fore-arc setting (fig. 5). 

AIPC (no date) evaluated the total organic carbon (TOC) 

of 151 outcrop samples and well cuttings of Tertiary shales 

collected between Zorritos (just north of the Talara Basin [fig. 

1]) and Talara (near the Portachuelo oil field); these included 

(1) 81 Eocene shale samples that ranged from 0.11 to 1.92 percent TOC; (2) 15 Mancora samples, 0.08 to 4.95 percent TOC; 

(3) 35 Heath shales, 0.24 to 3.86 percent TOC; (4) 13 Zorritos 

shales, 0.22 to 13.12 percent TOC; and (5) 7 Cardalitos shales, 

0.15 to 1.62 percent TOC. Values below 1 percent TOC would 

have low to marginal value as hydrocarbon source rocks, 

whereas concentrations equal to or above 1 percent TOC are 

potential source rocks. Kraemer and others (1999) believed 

that the Heath Formation is a hydrocarbon source rock for the 

Mancora and Zorritos Formations, and that a TOC value of 1.6 

percent and greater is needed for the Heath Formation to be a 

source rock. 

Probable onset of hydrocarbon migration was in midMiocene time, after the opening of the Gulf of Guayaquil by 

movement along the Dolores-Guayaquil megashear and creation of the Tumbes-Progreso subbasin. Close association of 

potential source and reservoir rocks indicates that accumulation of oil in reservoirs could have begun soon after the start of 

hydrocarbon generation. GC/MS data combined with active 

seeps indicate that there is still active migration in the basin. 

Reservoir Rocks 

Listed on the stratigraphic column of the Tumbes-Progreso and the Santa Elena portions of the Progreso Basin 

province (fig. 2) are formation names, notations for reservoir 

and potential hydrocarbon source rocks, and times of erosion 

and (or) nondeposition. Jaillard and others (1995) listed the 

Santa Elena Formation as being Maestrichtian through late 

Paleocene in age (fig. 2), whereas GeoMark (1998) and Petroconsultants (1996) indicated an Eocene age. The upper Eocene 

Seca Formation of Jaillard and others (1995) is probably the 

Santo Tomas, and their Eocene Punta Ancon Formation is 

the Atlanta/Olistrostrome Formation (fig. 2). Reservoir and 

source-rock intervals and times of migration, generation, and 

emplacement of hydrocarbons are shown on the events charts 

(figs. 4, 5).

The Lower Cretaceous Pinon Formation is composed 

of altered and metamorphosed tholeiitic lava associated with 

the midocean ridge basalts (MORB); the overlying Calentura 

Formation is pelagic shale (a possible source rock), tuff, and 

greywacke, and the Upper Cretaceous Cayo Formation is a 

reservoir facies in the Santa Elena block (figs. 4, 5) (Goossens 

and Rose, 1973; Lebrat and others, 1987). The Cayo Formation crops out on both sides of the Chongon-Colonche fault; it 

consists of about 2,000 m (6,600 ft) of upward-fining, coarsegrained volcaniclastic sandstone and conglomerate, including high- to low-density turbidites with shaly intercalations 

(Jaillard and others, 1995). The Cayo Formation was mainly 

deposited in a shallow-marine environment with west-directed 

transport (Benitez, 1990). Conformable contacts with underlying fine-grained deposits of the Calentura Formation (Benitez, 

1990; Marksteiner, R., and Aleman, A., 1991, Coastal Ecuador, technical evaluation agreement: unpublished internal 

report, Amoco Production Company and Petroecuador, v. 1, 

218 p.) indicate that an important tectonic and geodynamic 

change occurred by Late Cretaceous (late Coniacian-early 

Santonian) time (Jaillard and others, 1995). The Cayo and 

Calentura Formations are the approximate age equivalents of 

the Villeta and Napo Formation in the Putumayo and Maranon 

Basins of Colombia, Ecuador, and Peru. The Cretaceous Pinon 

Formation in the Santa Elena block is the age equivalent of the 

Caballos and Hollin Formations in the Putumayo and Maranon 

Basins of Colombia, Ecuador, and Peru.

A listing of production from the Upper Cretaceous to 

Paleocene Santa Elena Formation by Petroconsultants (1996) 

probably includes production from the underlying Cayo Formation. The Santa Elena Formation is pelagic black chert and 

tuff (Jaillard and others, 1995); probable reservoirs are marine 

sandstones. Deposition of the Santa Elena Formation was followed by substantial tectonic subsidence that accommodated 

thick, uppermost Paleocene turbidites of the Azucar Group 

(Jaillard and others, 1995). The upper Paleocene to lower 

Eocene Azucar Group is only located south of the ChongonColonche fault and is composed of at least 1,500 m (5,000 ft) 

of conglomerates, pebbly sandstones, sandstones, and shales 

(Bristow and Hoffstetter, 1977) that form reservoirs and seals. 

Figure 16 (facing page). The relative concentrations of nickel and 

vanadium in oils from the Progreso (6083) and Talara (6081) Basin 

provinces. A, Relative concentrations of nickel and vanadium. B, 

Concentration of nickel relative to the ratio of nickel to nickel plus 

vanadium. The ratio of nickel and vanadium tends to be constant 

through time and can indicate different source rocks and types 

of source rocks, such as limestones or marine shales. Distribution of data for A and B indicates that there is one Tertiary source 

rock, or rocks, for oils from the provinces. The two Progreso 

Basin province probable Tertiary samples are grouped with those 

of the Talara Basin province. 
NICKEL (PPM)

NICKEL/(NICKEL + VANADIUM)

A

B

0.0 0.2 0.4 0.6 0.8 1.0

Pennsylvanian reservoir

Tertiary reservoirs 

Unknown reservoir ages

Progreso Basin samples

NICKEL (PPM)

VANADIUM (PPM)

30

25

20

15

10

5

0

35

30

25

20

15

10

5

0

0 10 20 30 40 50 60

Petroleum Occurrence 21
22 The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador

Direction of the paleocurrent was from the northeast; the 

Azucar Group is faulted and contains east-, northeast-to-west-, 

and southwest-trending folds with vertical axial planes (Jaillard and others, 1995). Sediments were deposited on submarine fans largely by high-density (with minor low-density) 

turbidite flows (Moreno, 1983; Benitez, 1983). Source of sediments are the underlying Santa Elena and Guayaquil Formations (lateral equivalent in the Chongon-Colonche Cordillera) 

and continental basement and volcanic rocks (Marksteiner, R., 

and Aleman, A., 1991, Coastal Ecuador, technical evaluation 

agreement: unpublished internal report, Amoco Production 

Company and Petroecuador, v. 1, 218 p.). The Azucar Group is 

unconformably overlain by the lower Eocene El Rosario Formation, which produces mostly oil from fluvial conglomerates 

in the La Mata Chivato 1 and Santa Paula fields in the Santa 

Elena block. Early Eocene time is marked by a widespread 

depositional hiatus across the province; formations south of 

the Chongon-Colonche Cordillera fault zone are difficult to 

differentiate and the lower Eocene El Rosario Formation, and 

other early Eocene units can vary in thickness by as much as 

350 m (1,100 ft) (Jaillard and others, 1995). 

Five fields in the Santa Elena block produce oil and gas 

from the lower to middle Eocene Wildflysch Olistrostrome; 

reservoirs are marine chert facies (Petroconsultants, 1996). 

The Wildflysch Olistrostrome is unconformably overlain by 

the middle to upper Eocene Socorro Formation, which consists 

of laminated shales, siltstones, and fine-grained sandstones 

that were deposited in an outer shelf environment; these have 

interbedded thick-bedded turbidite sandstones (Jaillard and 

others, 1995) that are the primary reservoir facies. Biostratigraphic analysis of flute casts in turbidites in middle and upper 

Eocene strata in the Santa Elena block indicate the sediments 

were sourced from the south and are similar to those of the 

Talara Basin province; the primary difference is that strata 

near the Ancon field (fig. 1) are closer to the subduction zone 

and exhibit spectacular turbidites that are not exposed in outcrop in the Talara Basin province (Raez Lurquin, 1999). The 

Socorro Formation grades upward into the Seca (probably the 

Santo Tomas) Formation, which is a shallow shelf sequence 

of laminated shales, siltstones, and marls, and thin-bedded 

sandstones and subordinate turbidites (Jaillard and others, 

1995) that are the main reservoir intervals. The Santa Elena 

block produces from mostly Eocene reservoirs of the Atlanta 

sandstone/Olistrostrome; maximum thickness of the Eocene 

section is 4,800 m (15,780 ft)(AIPC, no date). The Carmela 

and Ancon fields both produce oil and gas from Atlanta/

Olistrostrome strata.

Figure 17. Distribution of delta 13C isotopes for saturated and aromatic hydrocarbons, Progreso and Talara Basin provinces 

(GeoMark, 1998). Clustering of data indicates that sampled oils from the Talara and Progreso Basin provinces have common Tertiaryage source rocks. This is also true for the one oil sample from the Pennsylvanian Amotape Formation.

DELTA 13C SATURATES

DELTA 13C AROMATICS

-20.0

-20.5

-21.5

-21.0

-23 -22.5 -22 -21.5 -21

Pennsylvanian reservoir age 

Tertiary reservoirs

Unknown reservoir ages

Progreso Basin samples
Primary oil and gas reservoirs of the Tumbes-Progreso 

subbasin are the upper Oligocene to possibly lower Miocene 

Heath Formation, and marine sandstones of the Miocene 

Zorritos and Cardalitos (Subibaja) Formations. The Zorritos 

Formation in offshore Peru is 1,500 to 2,000 m (5,000 to 6,500 

ft) thick with alternating sequences of sandstone and shale; 

sandstones are mostly fine grained to silty and were deposited 

in continental to middle neritic environments (AIPC, no date). 

Thickness range of the sedimentary section in the TumbesProgreso subbasin is 6,000 to 15,000 m (20,000 to 50,000 

ft), increasing seaward (AIPC, no date; Zuñiga-Rivero and 

Hay-Roe, 1998). Kraemer and others (1999) believed that the 

Mancora and Zorritos Formations sandstones form good

quality reservoirs. 

The Quaternary La Cruz Formation is a greenish-gray 

shale with benthonic and planktonic foraminifera of sublittoral 

depositional environments, and the Quaternary Tablazo Formation is primarily marine coquinas, sand, and gravel (AIPC, 

no date; Sanz, 1988). Two fields in the Santa Elena block 

produce from the Tablazo Formation and Eocene formations; 

because Quaternary shales are probably immature for oil, the 

source could have been Eocene or other Tertiary marine shales 

or those of underlying Upper Cretaceous shales. These formations are also potential reservoir rocks in the Peru Bank, an 

isolated wedge of Neogene-Paleozoic sediments that was not 

affected the Neogene erosion that had removed the Paleogene 

through Cretaceous strata from most of the Tumbes-Progreso 

subbasin. Sedimentary thickness at the Peru Bank is about 

16,000 m (52,000 ft) (Zúñiga-Rivero and others, 1999). 

Zúñiga-Rivero, Keeling, and Hay-Roe (1998a) indicated that 

water depth in places around the Peru Bank is less than 200 m 

(650 ft).

Traps and Seals

Primary traps in the Progreso Basin province are structural. Seismic data indicate a variety of trapping mechanisms 

for the Talara and Progreso Basin provinces, from rollovers 

and updip closures against faults to turbidite channel deposits 

and onlap onto paleohighs (AIPC, no date). Moderate folding 

in the Progreso Basin province probably controlled accumulation of oil and gas from Cretaceous source rocks, but the 

middle to late Tertiary extensional regime was associated with 

the characteristic high-angle normal faulting that redistributed 

the hydrocarbons, leaving them primarily in fault-block reservoirs (Zúñiga-Rivero, Keeling, and Hay-Roe, 1998a). Evidence for growth faulting in the province (figs. 6, 7) is mostly 

from concurrent deposition of Paleocene to lower Miocene 

formations on top of the metamorphosed Amotape and Precambrian basement rocks (AIPC, no date). Kraemer and others 

(1999)(figs. 6, 7) identified two main groups of traps for the 

Neogene section of the offshore Tumbes-Progreso subbasin: 

(1) stratigraphic unconformity traps that formed at the 

beginning of the second tectonostratigraphic stage (middle to 

early late Miocene, stage II, fig. 6); and (2) structural roll-over 

traps that were produced by normal growth faulting during the 

third stage (late Miocene to present, stage III, fig. 6).

Sediment sources were mainly from the east, northeast, 

and southeast (Perupetro, 1999; Pindell and Tabbutt, 1995); 

depositional patterns associated with these fluvial, shoreline, 

turbidite, marine, and other facies strongly influenced types 

and locations of seals. Overlying and interbedded marine 

shales are the major reservoir seals, both for shallow and 

deep-water deposits. Lateral seals are (primarily normal) fault 

offsets and lateral depositional or erosional pinch-outs of the 

mostly marine sandstones into shales. 

Conclusions 

The Progreso Basin province of southwestern Ecuador 

and northwestern Peru is composed of the Santa Elena block 

and Tumbes-Progreso subbasin. The province has a complex 

history that includes transtensional, extensional, and compressive tectonics. The province is dissected by the northeasttrending Dolores-Guayaquil megashear zone. The western 

boundary of the province is approximated by the zone where 

the Nazca Plate is being subducted under the South American 

Plate. 

The onset of hydrocarbon generation was probably during the Miocene. Migration of hydrocarbons likely beginning in middle Miocene time, after opening of the Gulf of 

Guayaquil by right-lateral and rotational movement along 

the Dolores-Guayaquil megashear and associated creation of 

the Tumbes-Progreso subbasin. The probable short migration 

distances result from close vertical association between most 

reservoir intervals and the marine shales that are the likely 

source rocks. Probable hydrocarbon source rocks are the Oligocene and Miocene Mancora, Heath, Zorritos, and Cardalitos 

Formations across the province, as well as the Lower Cretaceous Calentura Formation in the Santa Elena block. 

Production in the Santa Elena block is from Upper 

Cretaceous through Eocene and from Holocene formations; 

reservoirs are mostly sandstone that was deposited in deep and 

shallow marine, shoreline, deltaic, and fluvial environments. 

Tablazo Formation oil was probably sourced from Eocene 

and older marine shales. Oil and gas in the Tumbes-Progreso 

subbasin is produced from the Oligocene Heath Formation and 

the Oligocene and Miocene Zorritos Formation. The primary 

seals across the province are overlying and interbedded shales 

of mostly marine environments. Primary traps are structural; 

middle to late Tertiary extensional tectonics resulted in highangle normal faulting that redistributed hydrocarbons and left 

them mainly in fault-block reservoirs. Expected stratigraphic 

and combination stratigraphic-structural traps would include 

updip pinch-outs of turbidite, fluvial, and marine sandstones 

against shales. 

Conclusions 23
24 The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador

Selected References

Baldock, J.M., 1982, Geología del Ecuador, boletin explicativo del mapa geológico del Ecuador, escala 1:1,000,000: 

Dirección General de Geología y Minas, Quito, Ecuador, 

66 p.

Benitez, S., 1983, Contribución al estudio de las cuencas sedimentarias del Suroeste ecuatoriano: Actas del III Congreso 

Ecuatoriano de Ingenierea, Geología, Minería y Petróleo, 

Guayaquil, v. I.A., 41 p. 

Benitez, S., 1990, Estratigrafía de las formaciones Cayo y 

Guayaquil en la Cordillera Chongón-Colonche: Hacia una 

redefinición. Parte I: Geociencia, Guayaquil, v. 3, p. 7–11.

Bristow, C.R., and Hoffstetter, R., 1977, Ecuador: Lexique 

International de Stratigraphie, CNRS ed., Paris, v. Va2, 

410 p.

Canfield, R.W., 1966, Reporte geológico del la costa ecuatoriana: Informe del Ministerio Industría y Comercio, Asesoria 

Técnica de Petróleos, Quito, 150 p. 

Egüez, A., Marocco, R., and Perez, V.H., 1991, Memoria 

téchnica del mapa tectónico del Eduador: Informe inédito 

del proyecto EPN-CLIRSEN-IPGH-ORSTOM, Quito 

(unpublished report), 1 map, scale 1:1,000,000, 44 p.

Environmental Systems Research Institute Inc., 1992, ArcWorld 1:3M digital database: Environmental Systems 

Research Institute, Inc. (ESRI), available from ESRI, Redlands, Calif., scale: 1:3,000,000.

GeoMark Research, Inc., 1998, Oils; Oil Information Library 

System digital database, Version 1.0: Database available 

from GeoMark Research, Inc., 9748 Whithorn Drive, 

Houston, TX 77095, U.S.A., 1 CD–ROM.

Gonzales Torres, Enrique R., 1999, Modelo sedimentario 

de la Formacion Basal Salina Cuenca Talara: Ingepet ʼ99 

seminar, Lima, Peru, Oct. 26–29, EXPR-1-EG-13.pdf, 

16 p.

Goossens, P.J., and Rose, W.I., 1973, Chemical composition 

and age determination of tholeiitic rocks in the Basic 

Cretaceous Complex, Ecuador: Geological Society of 

America Bulletin, v. 84, p. 1043–1052.

Handschumacher, D.W., 1976, Post-Eocene plate tectonics 

of the eastern Pacific, in Sutton, G.H., and others, eds., 

The geophysics of the Pacific Ocean Basin and its margin: 

American Geophysical Union, Geophysical Monograph 19, 

p. 177–202.

Haq, Bilal U., Hardenbol, Jan, and Vail, Peter R., 1987, 

Chronology of fluctuating sea levels since the Triassic: 

Science, v. 235, no. 4793, p. 1156–1167.

Isaacson, P.E., and Diaz Martinez, E., 1995, Evidence for a 

Middle-Late Paleozoic foreland basin and significant paleolatitudinal shift, Central Andes, in Tankard, A.J., Soruco, R. 

Suárez, and Welsink, H.J., eds., Petroleum basins of South 

America: American Association of Petroleum Geologists 

Memoir 62, p. 231–249.

Jaillard, E., Ordonez, M., Benitez, S., Berrones, G., Jimenez, 

N., Montenegro, G., and Zombrano, I., 1995, Basin 

development in an accretionary, oceanic-floored fore-arc 

setting—Southern coastal Ecuador during Late CretaceousLate Eocene time, in Tankard, A.J., Suarez Soruco, R., and 

Welsink, H.J., eds., Petroleum basins of South America: 

American Association of Petroleum Geologists Memoir 62, 

p. 615–631.

Karig, D.E., and Moore, G.F., 1975, Tectonically controlled 

sedimentation in marginal basins: Earth and Planetary 

Science Letters, v. 26, p. 233–238.

Kingston, John, 1994, Undiscovered petroleum of southern 

South America; U.S. Geological Survey Open-File Report 

94–559, 443 p.

Klett, T.R., Ahlbrandt, T.S., Schmoker, J.W., and Dolton, G.L., 

1997, Ranking of the worldʼs oil and gas provinces 

by known petroleum volumes: U.S. Geological Survey 

Open-File Report 97–463, 1 CD– ROM, Adobe Acrobat 

format.

Kraemer, P., Weiner, A., and Alvarez, P., 1999, Evolución 

tectonoestratigráfica de la cenca de Tumbes-Progresooffshore Peru: Exploration and exploitation of petroleum 

and gas, Perupetro Ingepet ʼ99 seminar, Lima, Peru, Oct. 

26–29, EXPR-1-PK-07.pdf, 9 p.

Kraemer, P.E., Weiner, A., and Alvarez, P., 2001, Tectonoestratigraphic framework of a transtensional forearc 

basin—The Tumbes Basin of northwestern Perú: American 

Association of Petroleum Geologists Bulletin, v. 85, no. 13, 

CD–ROM supplement.

Kronman, G.E., Rushworth, S.W., Jagiello, K., and Aleman, 

A., 1995, Oil and gas discoveries and basin resource predictions in Latin America, in Tankard, A.J., Suarez Soruco, R., 

and Welsink, H.J., eds., Petroleum basins of South America: 

American Association of Petroleum Geologists Memoir 62, 

p. 53–61.

Lebrat, M., Megard, F., Dupuy, C, and Dostal, J., 1987, Geochemistry and tectonic setting of pre-collision Cretaceous 

and Paleogene volcanic rocks of Ecuador: Geological Society of America Bulletin, v. 99, p. 569–578.

Lonsdale, P., 1978, Ecuadorian subduction system: American 

Association of Petroleum Geologists Bulletin, v. 62, no. 12, 

p. 2454–2477.
Magoon, L.B., and Dow, W.G., 1994, The petroleum system, 

in Magoon, L.B., and Dow, W.G., eds., The petroleum 

system—From source to trap: American Association of 

Petroleum Geologists Memoir 60, p. 3–23.

Marocco, R., Lavenu, A., and Baudino, R., 1995, Intermontane 

Late Paleogene-Neogene Basins of the Andes of Ecuador 

and Peru—Sedimentologic and tectonic characteristics, in 

Tankard, A.J., Suarez Soruco, R., and Welsink, H.J., eds., 

Petroleum basins of South America: American Association 

of Petroleum Geologists Memoir 62, p. 597–613.

Miller, J.J., Lee, M.W., and von Huene, R., 1991, An analysis 

of a seismic reflection from the base of a gas hydrate zone, 

offshore Peru: American Association of Petroleum Geologists Bulletin, v. 75, no. 5, p. 910–924.

Moreno, A., 1983, Estratigráfia detallada del Grupo Azúcar en 

los acantilados de Playas: Ing. Dissertation, Escuela 

Superior Politecnica del Litoral, Guayaquil, 182 p.

Pardo, A., and Pisconte, J., 2002, Zorritos y al historía de la 

industria del petroleo en el Peru: Perupetro Ingepet 2002 

seminar, Lima, Peru, Nov. 6–8, 1 CD–ROM, EXPL-3-AP29.pdf, 11 p.

Pardo Casas, F., and Molnar, P., 1987, Relative motion of the 

Nazca (Farallon) and South American Plates since Late 

Cretaceous time: Tectonics, v. 6, p. 233–248.

Perupetro, 1999, International bidding round–Offshore and 

coastal blocks: Perupetro information booklet, Avenida Luis 

Aldana, 320 San Borja, Lima, Peru, 47 p. 

Petroconsultants, 1996, Petroleum Exploration and Production and PetroWorld 21 databases: Petroconsultants, Inc., 

P.O. Box 740619, 6600 Sands Point Drive, Houston TX 

77274–0619, USA or Petroconsultants, Inc., P.O. Box 152, 

24 Chemin de la Mairie, 1258 Perly, Geneva.

Pilger, R.H., 1984, Cenozoic plate kinematics, subduction, 

and magmatism—South American Andes: Journal of the 

Geological Society of London, v. 141, p. 793–802.

Pindell, J.L., and Tabbutt, K.D., 1995, Mesozoic-Cenozoic 

Andean paleogeography and regional controls on hydrocarbon systems, in Tankard, A.J., Soruco, R. Suárez, and 

Welsink, H.J., eds., Petroleum basins of South America: 

American Association of Petroleum Geologists Memoir 62, 

p. 101–128.

Raez Lurquin, M.A., 1999, Tectonica en la cuenca Talara 

costa-afuera, nor-oeste Peru—Exploration and exploitation 

of petroleum and gas, Perupetro Ingepet ʼ99 seminar, Lima, 

Peru, Oct. 26–29, EXPR-1-MR-12.pdf, 19 p.

Roperch, P., Megard, F., Mourier, C., Laj, T., Clube, T., and 

Noblet, C., 1987, Rotated oceanic blocks in western 

Ecuador: Geophysical Research Letters, v. 14, p. 558–561.

Sanz, V.R., 1988, Geológia y potencial hidrocarburifero de la 

región Mancora-Tumbes: Ph.D dissertation, Universidad 

Nacional Mayor de San Marcos, 119 p.

Schenk, C.J., Viger, R.J., and Anderson, C.P., 1999, Maps 

showing geology, oil and gas fields, and geologic provinces of South America: U.S. Geological Survey Open-File 

Report 97–470D, 1 CD–ROM, Adobe Acrobat v. 4.0 pdf 

format. http://greenwood.cr.usgs.gov/energy/WorldEnergy/

OF97-470D/

Seranne, Michel, 1987, Evolution tectono-sédimentaire du 

Bassin de Talara (nord-ouest du Perou): Bulletin Inst. Fr. Et. 

And., v. XVI, no. 3–4, p. 103–125.

Shepherd, Glenn L., and Moberly, Ralph, 1981, Coastal structure of the continental margin, northwest Peru and southwest Ecuador, in Kulm, LaVerne D., Dymond, Jack, Dasch, 

E. Julius, Hussong, Donald M., and Roderick, Roxanne, 

eds., Nazca Plate—Crustal formation and Andean convergence: Geological Society of America Memoir No. 154, 

p. 351–391.

Travis, R.B., Gonzales, G., and Pardo, A., 1976, Hydrocarbon 

potential of coastal basins of Peru: American Association of 

Petroleum Geologists Memoir 25, p. 331–338.

U.S. Geological Survey World Energy Assessment Team, 

2000, U.S. Geological Survey World Petroleum Assessment 

2000—Description and results: U.S. Geological Survey 

DDS 60, 4 CD–ROMs. http://greenwood.cr.usgs.gov/

energy/WorldEnergy/DDS-60/

Zúñiga-Rivero, Fernando, and Hay-Roe, Hugh, 1998, Oil, gas 

potential in shallow water—Peruʼs continental shelf basins: 

Oil and Gas Journal, November 16, 1998, p. 92–96. 

Zúñiga-Rivero, Fernando, and Hay-Roe, Hugh, 1999, Talara—

A new look at an old petroleum basin: Exploration and 

exploitation of petroleum and gas, Perupetro Ingepet ʼ99 

seminar, Lima, Peru, October 26–29, EXPR-1-FZ-15.pdf, 

9 p.

Zúñiga-Rivero, Fernando, Keeling, J.A., and Hay-Roe, Hugh, 

1998a, Attractive potential seen in 10 subbasins off Peru: 

Oil and Gas Journal, September 7, 1998, p. 117–122.

Zúñiga-Rivero, Fernando, Keeling, J.A., and Hay-Roe, Hugh, 

1998b, Peru onshore-deepwater basins should have large 

potential: Oil and Gas Journal, October 19, 1998, 

p. 88–95.

 Selected References 25