SOCIETY OF ECONOMIC GEOLOGISTS, INC.

GUIDEBOOK SERIESVolume 46

Prepared for the Society of Economic Geologists Field TripSeptember 26, 2014

Field Trip LeaderT. Brown, S. Diakov, and S. McAnally

T. Brown, Editor

The Cripple Creek Mining District of Colorado in 2014

GUIDEBOOK SERIES

OF THE

SOCIETY OF ECONOMIC GEOLOGISTS, INC.

Guidebook 46

Print

ISSN 1547-3090

ISBN 978-1-629490-50-2

CD-ROM

ISSN 1547-3104

ISBN 978-1-629490-51-9

Online

ISSN 2374-6955

ISBN 978-1-629494-83-8

Digital version (on CD-ROM or as a pdf file) available from

Society of Economic Geologists, Inc.

7811 Shaffer Parkway

Littleton, Colorado 80127

Tel. 1.720.981.7882

Fax: 1.720.981.7874

Bookstore: www.segweb.org/store

Publication date: September 2014

CONTENTS

Preface Tim Brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii

Road Log for the Cripple Creek Field Trip Tim Brown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Geology of the Cripple Creek district Part I;

General summary of geologic features and regional setting [Reprint] Eric Jensen and Mark Barton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Geology of the Cripple Creek district Part II;

Time-space synthesis of magmatic and hydrothermal activity [Reprint]

Eric Jensen and Mark Barton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Geologic map of the Cripple Creek District (Lindgren and Ransome, 1906) and the field trip

stops. The geologic contact between the Oligocene volcanic rocks and the Precambrian rocks is

shown by the red line.

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PREFACE

The Cripple Creek Mining District is world-class district by any definition (ounces produced, dollars

generated, publications authored, etc.). The district, located 20 air miles (32 km) west of Colorado

Springs, Colorado, has produced over 24 million ounces of gold (750 tonnes) since its discovery in

1891. Current reserves (year end 2013) stand at 4.7 million contained ounces (146 tonnes) and

exploration efforts continue to search for additional resources.

The bulk of the gold mineralization has been produced from narrow, high-grade veins hosted in an

Oligocene, alkaline, diatreme-intrusive complex. Gold has also been produced from mineralization

hosted by the Precambrian rocks where the vein systems were strong enough to penetrate from the

diatreme. More recently, gold has been produced by bulk mining methods in the low-grade haloes

around the vein systems.

The recent district publications include a PhD. dissertation completed by Eric Jensen through the

University of Arizona in 2003. The document is too big to be included in the guidebook but

interested readers are encouraged to take advantage of this work. Papers by Eric Jensen and Mark

Barton (2007) are the most recently published works for a GSA/SEG field trip in October 2007.

They have both been included in this guidebook with permission.

The mine is operated by Cripple Creek and Victor Gold Mining Company, a wholly owned

subsidiary of AngloGold Ashanti, Ltd. They are gratefully acknowledged for allowing the

publication and the tour.

TIM BROWN

August 2014

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