Plate 1Geologic Map of theYanacocha District

Cajamarca, PeruGeologic mapping of the central part of the Yanacocha District conducted prior to 2001: D. Abarca, J. Barreda, R. Bartra, E. Calderón, M. Changanaqui,J. Edwards, J. Escalante, B. Harvey, T. Klein, B. Leach, C. Loayza, A. Longo, S. Myers, R. Pinto, A. Quiroz, M. Rutti, and C. Velasco.

This geologic map was completed and compiled as part of anOregon State University doctoral dissertation (Longo, 2005)

Kls Limestone and marls Cajamarca Fm. and Pulluicana-Quillquiñán Groups

Quartzite and shales Goyllarisquizga GroupKq

Cretaceous Sedimentary Rocks

Calipuy Group Volcanic Rocks

Atazaico Andesite Lava and Dome Rocks

Colorado Pyroclastic and Flow-Dome Sequence

Azufre Andesite-Dacite Lava and Dome Rocks

San Jose Ignimbrite and Dome Sequence

Ted - early hb-bi dacite intrusionsEarly Quilish-Exaltado Dacite

Typ -Yanacocha feldspar porphyry and diatreme breccia

Coriwachay Dacite

La Quinua Sediments (Pliocene ?)Tl - Tu�aceous Lacustrine Sediments

Yanacocha gravels (Pleistocene)Qg - �uvial and glacial deposits

Tulx - upper laminated rocks

Tcd - Corimayo-Quilish-Punta Negra dacite domes

Typq -

Tcyd -

Tbxh - Yanacocha phreatic-hydrothermal breccia

Tnrd - Negritos rhyolite domes

Tnri - Negritos rhyolite ignimbrite

Tusjd - Upper San Jose px-hb dacite dome rocks

Tmsjd - Middle San Jose hb-bi dacite dome rocks

Tlsjd - Lower San Jose px-hb dacite dome rocks

Tusj - Upper San Jose px-hb dacite spatter ignimbrite

Tmsj - Middle San Jose hb-bi andesite-dacite ignimbrite

Tlsj - Lower San Jose px-hb andesite-dacite ignimbrite

Tmlx - Middle laminated rocks

Tuphad - upper px-hb andesite-dacite dome rocks

Tupha - upper px-hb andesite-dacite lava dominant rocks

Tmmp - hb andesite porpyritic lavas and intrusions

Tmmi - Maqui Maqui Ignimbrite (inc. Cori Coshpa tu�)

Tllx - Lower laminated rocks

Tlphad - lower px-hb andesite dome rocks

Tlpha - lower px-hb andesite lava dominant

Tpt - Peña de Leon tu� (eastern side)

Tcfd - Cerro Fraile pyroclastic sequence

Tlalc - Chaupiloma lower andesite lahar sequence

Tlalt - Tual lower andesite lahar sequence

Tha - Huambo Cancha andesite

Tmcv - Minas Congas volcanic rocks (eastern side)

Ro

ck

s o

f t

he

Ya

na

co

ch

a V

olc

an

ics

Stratigraphic Legend

Low

er M

ioce

neM

idd

le M

ioce

ne

Up

per

Mio

cen

e

altered porphyry rocks and diatremes(no quartz phenocrysts)

Yanacocha Lake rhyolite-dacite domedikes and diatreme

Yanacocha quartz dacite porphyry plugs and diatreme

and intrusions

Unmapped areas

fault well locatedpossible faultfault contact ~30mfault contact ~15mprominent circularfeature

possible contactcontact ~30mcontact ~15mcontact ~5mcontact welllocated

ContactsFaults

Structural attitudes omitted for clarity (see Longo, 2005)

Limits of the argillic and advanced argillic alteration in outcrop

Limits of weak argillic and advancedargillic alteration

Limits of alteration concealed or buried

Yanacocha

6ºS

80

ºW

Index Map of Acknowledgements

Peru

7650

00E

7850

00E

9225000N2

5

9

81

4637

9240000N

9235000N

9230000N

9225000N

9220000N

9215000N

7600

00E

7650

00E

7700

00E

7750

00E

7800

00E

7850

00E

7550

00E

0 5

Kilometers

�

Tcfd

Tcfd

Tcfd

Tcfd

Tcfd

Tcfd

TcfdTcfd

Tcfd

Tcfd

Tcfd

Tha

Tlalt

Tlalt

TlaltTlalt

Tlalt

TlalcTlalc

Tlalc

Tlalc

Tlalc

Tlalc

Tlalc

Tlalc

Tpt

Tpt

Tpt

Tmcv

Kls

Kls

Tpt

KlsKls

Kq

Kq

Ted

Ted

Ted

Tl

Tlpha

Tlpha Tlpha

Tlpha

Tlpha

Tlpha

Tlpha

Tlpha

Kq

Tlphad

Tlphad

Tlphad

Qg

Qg

Qg

TuphadTuphad

Tmlx

Tlsj?

Tmsj

Tusj

Tusj

TlsjTlsj

Kls

Tmsj

Tmsj

Tmsj

Tnri

Tmmi

Tmmi

Tmsj

Tupha

Tuphad

Tuphad

Tcd

Tcd

Tupha

Tlsjd

Tusjd

TmsjdTuphad Chaquicocha Gold Deposit Outline

Cerro Regalado

Quilish

Tual

Chaupiloma

Huambo Cancha

Cerro Fraile

Antibuyoc

Cerro Negro

El Arco

BarrancoTatiana Pachanes

Sorpresa

China Linda

Elita

Ocucho

Alto Machay

Los Pinos

Exaltado

Cerro Atazaico

HornamoSugares

Maqui Maqui

Co Yanacocha

Pampa LargaColorado Graben

Pabellon

Cori Coshpa

Punta Negra

Arnacocha

Corimayo

Carachugo

Chaquicocha

Azufre

Pampa Cerro Negro

Negritos

La Quinua Graben

Pampa CorimayoSan Jose

Baul

Machay

Sacsha

sur

Cajamarca

Otuzco Trough

Combayo

Otuzco

Ventanillasde Combayo

Quebrada Honda

La Quinua Facility

Lake district

Paquerumi-Huacataz

Cerro Collotan

Stratacone

glacial deposits

Kupfertal

norteEncajon

Tapado

Granja Porcon

QuecherLa Quinua dome

Co Cantaalta Combayo - place name of locality (see text)