107°10'

107°10'

107°20'

107°20'

107°30'

107°30'

107°40'

107°40'

107°50'

107°50'

38°00'

38°00'

37°50'

37°50'

37°40'

37°40'

37°30'

37°30'

550

Map of Mineralogy, Vegetation, and Hydrothermal Alteration Type 

Generated From ASTER Satellite Data, San Juan Mountains, Colorado

Modeled Hydrothermal Alteration Type

By

Barnaby W. Rockwell

2012

ASTER SWIR detector "scratch":

pyrophyllite, alunite, and kaolinite 

detections in this region are unreliable ASTER SWIR detector "scratch":

dolomite, jarosite, and opal/chalcedony

detections in this region are unreliable

550

550

Telluride

Sneffels

Trout

Lake

Engineer

Mountain

Potato

Hill

Silverton

Ophir

Red

Mountain

Ouray Lake City

Lake

San Cristobal

Continental 

Reservoir

Rio Grande

Reservoir

Animas River

Animas River

Min e ral

Creek

Cascade

Mountain

Red

Mountain

Broken

Hill

Gladstone

Williams Creek

Reservoir

149

149

149

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Map 3190

Sheet 4 of 5

Pamphlet accompanies Map

Base image is derived from multiple sources and served by ESRI 

http://goto.arcgisonline.com/maps/World_Imagery

World Geodetic System 1984 (WGS 84)

Projection: Universal Transverse Mercator, zone 13

ASTER Scene ID SC:AST_L1B.003:2011894123, acquired September 12, 2000 at 

http://glovis.usgs.gov/

Hydrothermal alteration type modeled from mineral assemblages identified through 

spectroscopic analysis of ASTER data described by Rockwell (2009).

ASTER data orthorectified using a Projective Transform to mosaicked TerraServer 

digital orthophoto quadrangles, digital raster graphics, and a 1/3-arc second digital 

elevation model (~10 m resolution) from the U.S. Geological Survey National

Elevation Dataset (NED, http://ned.usgs.gov/), provided by USGS Seamless Data 

Distribution System available at http://seamless.usgs.gov/. 

Data file name: sanjuans_aster_alteration5_pt-utm.img

This and other USGS information products are available at

http://store.usgs.gov/. 

U.S. Geological Survey

Box 25286, Denver Federal Center

Denver, CO 80225

To learn about the USGS and its information products visit

http://www.usgs.gov/. 

1-888-ASK-USGS

This report is available at:

http://pubs.usgs.gov/sim/3190/

Suggested citation:

Rockwell, B.W., 2012, Description and validation of an automated methodology for 

mapping minerology, vegetation, and hydrothermal alteration type from ASTER satellite 

imagery with examples from the San Juan Mountains, Colorado: U.S. Geological Survey 

Scientific Investigations Map 3190, 35 p. pamphlet, 5 map sheets, scale 100,000.

For more information concerning this publication, contact:

Center Director, USGS Central Mineral and

Environmental Resources Sciences Center

Box 25046, Mail Stop 973

Denver, CO 80225

(303) 236-1562

Or visit the Central Mineral and 

Environmental Resources Science Center Web site at:

http://minerals.cr.usgs.gov/

Any use of trade, product or firm names is for descriptive purposes only and does not 

imply endorsement by the U.S. Government.

Although this information product, for the most part, is in the public domain, it also 

contains copyrighted materials as noted in the text. Permission to reproduce 

copyrighted items for other than personal use must be secured from the copyright 

owner.

Although these data have been processed successfully on a computer system at the 

U.S. Geological Survey, no warranty expressed or implied is made regarding the display 

or utility of the data on any other system, or for general or scientific purposes, nor shall 

the act of distribution constitute any such warranty. The U.S. Geological Survey shall 

not be held liable for improper or incorrect use of the data described and/or contained 

herein.

APPROXIMATE MEAN

DECLINATION, 2000 TRUE NORTH

MAGNETIC NORTH

11°

550

550

Potosi

Hill

RAILROAD

RAILROAD

Graysill Mountain

Ophir loop

Vermillion

Peak

Lookout

Peak

Ames

La Junta

Peak

Red Mountain Creek

Chattanooga

145

Sunshine

Peak

Rio 

Grande

Rio 

Grande

Table

Mountain

Ute Ridge

Rio Grande

Pyramid

Whitecross

Mountain

Publishing support provided by: 

Denver Publishing Service Center

Manuscript approved for publication on Nov. 14, 2011

37° 37°

41° 41°

109° 102°

109° 102°

30 × 60 minute series grid

1:100,000 scale

COLORADO

MAP LOCATION

DURANGO

SILVERTON

NUCLA MONTROSE

DOVE

CREEK

CORTEZ

SAGUACHE

DEL 

NORTE

ANTONITO

Lake Fork

Gunnison

River

EXPLANATION

Alteration type and key mineral assemblages grouped by

relative net acid production and acid neutralizing capacity

Outline of ASTER scene footprint

Phyllic (QSP)

Pyritic (jarosite)

Highly pyritic QSP ± hydrous silica

argillic (or clay-bearing rocks)

Argillic + ferric iron

propylitic (or carbonate rocks)

Propylitic + ferric iron

Propylitic + sericite

High net acid production (NAP)

Advanced argillic

Moderate to high NAP (variable pyrite content)

Low to moderate NAP

Moderate to high acid neutralizing capacity (ANC)

Propylitic + sericite + ferric iron

High ANC

Regional propylitic to weak QSP—

minor sericite + ferric iron

No significant NAP or ANC

Hydrous silica—Opal and (or) chalcedony

Regional propylitic—Fe/Mg sericite ± chlorite

1 0 1 2 3 4 5 6 7 8 9 10 KILOMETERS

SCALE 1: 100 000

1 0 1 2 3 4 5 6 7 8 MILES