RALPH N. BAKER General Electric Company-Space Division Beltsville, MD 20705 LANDSAT Data: A New Perspective for Geology

A review of the utilization of LANDSAT imagery for geological interpretation.

HE LANDSAT (formerly ERTS) satellite geologic mapping, mineral and petroleum T program has been in existence for just exploration, and natural hazards surveys. The over two years, and in this brief time has categories are arbitrary, and results of inves­ added a whole new dimension to the study of tigations might fit equally well into more our Earth. Scientists from all over the world than one of these. have used data measured by LANDSAT's sensors (telemetered down from a REGIONAL STRUCTURAL STUDIES 580-mile-high vantage point in space) to Several investigators studied regional monitor pollution and crop growth, explore structures and their relationships in LAND­ for minerals and petroleum, and conduct a SAT imagery, availing themselves of a per­ host of other investigations ranging from spective previously impossible to achieve.

ABSTRACT: The LANDSAT (formerly ERTS) program, while con­ ceived and implemented as a research and development project, has been used as an operational orbital remote sensing system providing data of considerable value to various branches of geology. Areas in which the satellite imagery has been found most useful include re­ gional interpretations ofgeologic structure,lupdating and verifying of geologic maps, mineral and petroleum exploration, and the monitor­ ing of natural hazards such as large-scale erosion and seismicity. Investigations in these areas of application demonstrate the wide variety of uses presently undertaken or envisioned for the future. Many benefits have already been felt; others will be seen in the near future where the promise ofmineral or petroleum concentration will be realized through conventional ground based and satellite explora­ tion techniques. LANDSAT will aid considerably in pinpointing the likely site; "hands on" geology will do the rest.

animal migration patterns to iceberg monitor­ Y. Isachsen of New York State's Geological ing. The mission, originally designed for re­ Survey used the IOO-by-IOO-mile images to search and development, has for all practical construct a mosaic of the State and neigh­ purposes been considered "operational" boring regions. This mosaic shows, at a from the user's point of view. glance, geologic relationships of New York To geologists, the regional overview and State's diverse terrain, major rock units, gla­ repetitive coverage of LANDSAT data has cial features, large scale lineaments, and cir­ been particularly useful, enabling them to cular structures (Figure I). Isachsen went take advantage of vegetation and sun angle into the field to verify the existence of many changes in theirattempts to unravel the phys­ of these features discovered in the LAND­ ical history and setting ofthe Earth. Success­ SAT mosaic, and demonstrated how one ful LANDSAT investigations in geology can could use satellite imagery to discern fea­ be grouped for convenience into four general tures unsuspected at a larger scale. categories: regional structural studies, Houston and Marrs, LANDSAT inves-

PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING, 1233 Vol. 41, No. 10, October 1975, pp. 1233-1239. 1234 PHOTOGRAMMETRIC E GINEERING & REMOTE SENSING, 1975

FIG. 1. LANDSAT mosaic and lineament map of eastern New York State (after Isachsen, 1973). tigators from the University of Wyoming, between surface and sensor, investigators studied geologic structures in Wyoming by have shown that much geological informa­ using a LANDSAT mosaic, and reported that tion can be derived from imagery where the their interpretations compared favorably ground is obscured by vegetation. with known ground truth ofthe region. While this region had been reasonably well mapped GEOLOGIC MAPPI G by conventional field surveys, the The LANDSAT overview and coverage Houston-Marrs study points out the possibil­ cycle makes map correction and verification a ity of interpreting poorly mapped regions natural application to geology. Investigators with a minimum of ground truth, time, and H. Blodget and A. Anderson of NASA's God­ cost with some measure of confidence. dard Space Flight Center constructed a In the East where climate is generally less three-image mosaic of southern Morocco arid than in some Western States, LANDSAT from which they were able to verify and mod­ investigators have still been able to collect ify previously mapped lithologic boundaries, valuable geologic information despite the and investigate relationships between struc­ heavier vegetation cover. For example, re­ tural character and mineral emplacement gional lineaments were discovered and map­ from a regional perspective. A common pro­ ped by Gold and co-investigators at Penn cedure among LANDSAT investigators has State, using LANDSAT imagery of the been to use the imagery as base maps upon thickly forested Pennsylvania Appalachians. which geologic interpretations of structure, A private consulting firm has applied lithology, and lineament patterns are computer-aided enhancementtechniques (in superimposed. Another team of inves­ this case General Electric Company's tigators, M. Abdel-Gawad and J. Silverstein IMAGE 100 multispectral image processing of Rockwell International, discovered that and display system) to imagery ofother areas LANDSAT images of Baja and the Gulf of in eastern Pennsylvania, with success in dis­ California showed several small islands to tinguishing rock outcrops oflimited areal ex­ have been misplaced on conventional maps, tent. Thus, while imagery ofarid regions has both in geographic location and in topo­ the obvious advantage of little interference graphic detail. LANDSAT DATA: A NEW PERSPECTIVE FOR GEOLOGY 1235

M. Viljoen ofSouth Africa used LANDSAT from LANDSAT has been accomplished imagery to unravel the geologic relationships using the following well-known geologic ofthe South African shield. This investigator principles: was able to distinguish between the granite­ • Mineralizing fluids from within the Earth gneiss craton, adjacent metomorphic mobile may follow the paths of least resistance to belts, and major "greenstone" intrusions. the surface; these paths are zones of weak­ The nature of these intrusions and their ness through the Earth's crust and occur characteristic relationship to the overall where the solid rock has been fractured and geologic setting was recognized by Viljoen to faulted. Thus, a concentration of "linea­ be similar to that found in metallic mineral ments", many ofwhich can be discerned in LANDSAT imagery, may well indicate mining districts in Canada (e.g., Sudbury, where the crust is weakest and, therefore, Ontario) and Western Australia, and suggests most likely to be mineralized. that the South African regions might contain • Some rock types discernible from orbital useful concentrations of minerals as well. In altitudes are characteristically associated this example, the roughly 34,OOO-square­ with certain types of minerals because they kilometer region surveyed in a single indicate similar formative conditions or alt­ LANDSAT frame could be broken down into eration through time. mineralization potential maps with consid­ • Mineralization may alter surface tones by secondary enrichment, vegetation stress erable savings in time and cost to mineral andJor chemical changes in the vicinity of exploration interests. On a larger scale, the ore body, all of which can indicate that perhaps the most impressive display of significant mineral concentration has taken LANDSAT's map~making capability can be place. seen in the mosaic of the 48 conterminous Using these and other, more subtle clues, United States, produced by the Soil Conser­ geologists using LANDSAT imagery have vation Service ofthe U. S. Department ofAg­ reported varying degrees of success in min­ riculture, and available to the public (Figure erai and petroleum exploration studies. Some 2). of these investigators have related LANDSAT-discovered Iineaments to known MINERAL AND PETROLEUM EXPLORATION mineral concentrations; many of these The majority of LANDSAT geology inves­ studies have been undertaken in the arid re­ tigations fall into this category primarily be­ gions ofWestern North America. E. Lathram cause ofthe direct impact on current and pro­ and other geologists of the U. S. Geological jected national needs. Mineral exploration Survey discovered a series ofintersecting re-

FIG. 2. Mosaic of continental United States compiled from LANDSAT imagery by USDA. 1236 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1975

gional lineaments in a rare cloud-free NIM­ and of little value as ore guides. With the BUS image ofAlaska. These lineaments were relationship demonstrated by these inves­ verified in LANDSAT imagery and enabled tigators, future exploration efforts should be the investigators to propose a radically dif­ simplified markedly (Figure 4). Another ferent picture of mineral emplacement in Californian, 1. Bechtold, demonstrated a Alaska. Earlier speculation suggested that similar correlation between tensional fis­ mineral deposits in Alaska were related to sures in the Lake Mead area (resulting from fold belts of the Canadian Cordillera. Based east-west crustal extension) and concentra­ on the occurrence of the newly discovered tions of gold, silver and other metallic ore regional fractures, Lathram and his cowork­ deposits. ers suggested that mineral emplacement An interesting multilevel geochemical ex­ might also have occurred at their intersec­ ploration approach was reported by M. Jen­ tions. The result is an alternate hypothesis for sen, ofthe University ofUtah, who correlated mineral emplacement in Alaska, certain to LANDSAT lineaments with positive aero­ stimulate interest in renewed exploration ef­ magnetic anomalies, and field-checked areas forts in areas formerly dismissed as non­ where they coincided. Soil samples were productive (Figure 3). analyzed for mercury vapor, and those areas Further to the south, California inves­ ofhighest mercury vapor concentration iden­ tigators E. Rich (1973), Abdel-Gawad, and tified for intensive exploration. Silverstein (1973) correlated mining Other investigators have attempted to cor­ localities with lineaments observed in relate mineral deposits with characteristic LANDSAT imagery. Abdel-Gawad and Sil­ surface tones extracted from LANDSAT im­ verstein, in particular, correlated mercury agery visually or by computer enhancement mining localities with a newly discovered set techniques. R. Vincent identified highly ox­ of transverse faults in the Coast Ranges. The idized terrain overlying iron ore deposits in altered serpentine host rock and geologic set­ the Atlantic City mining district ofWyoming ting of the mercury ore were non-definitive by computer ratioing reflectance values of selected pairs of ERTS bands. The results were analog ratio images, corrected for geometric and atmospheric effects, which showed the oxidation "halos" over the iron ore deposits. A. Goetz and others at JPL de­ veloped computer techniques for rock iden­ tification and structural analysis in the Col­ orado Plateau, eventually resulting in the discovery of perched aquifers, ground water sources badly needed by ranchers on the

EXPLANATION Coconino Plateau of southern Arizona. _Ni,Cr,Fe LANDSAT data have found application in CIIJ Cu, Mo, massive sulfides = "9. Sb.W petroleum exploration as well. Two investig­ - Mojor foult with surface expression ations have met with initial success in this area. E. Lathram in another phase of the study mentioned earlier discovered an un­ usual regional orientation in a series oflakes on the Alaskan Arctic Coastal Plain. The lakes, generally oval in outline, paralleled regional lineations and deviations in the local gravity and magnetic fields. Supporting ground truth coupled with LANDSAT data led the investigators to postulate the exis­ EXPLANATION tence of"dip" reversals and regional arching: =Hg. Sb. W _Ni,Cr.Fe factors which might indicate potential pe­ mJ Cu, Mo, mossi...e sulfide troleum accumulation (Figure 5). Similar ...... Crustal fractures - Mojor foult with surface expression geologic trends continue to the northeast, and have aroused the interest of the pe­ FIG. 3. Projected distribution of selected min­ troleum industry. erals in Alaska (after Lathram et aI., 1973). A. Theory ofassociaton with geosynclinal evolution Another investigation, headed by R. Col­ of western Cordillera. B. Theory of association lins ofEason Oil Company (Oklahoma City), with crustal fractures as observed in satellite im­ correlated "hazy" surface tones discovered agery. in LANDSAT imagery ofthe Anadarko Basin N )5"

t"" > oZ Vl ~ o ..,> ?­ > Z t'l ~ '"0 t'l ::0 Vl '"0 t'l (").., :< t'l N )4" o"r1 ::0 (') EARTHQUAKE EP IeENTERS LEGEND t'l L!l- ~RGNI TUDE UNKNOWN ~ ... Fault with evidence '-~AGNITUDE o of recent movement O. - 4.0 x-~AGNtTUDE t"" KNOW FAULTS 4.1 - 4.9 O-MAGNITUDE 5.0 - 5.4 o FAULTS INFERRED FRO .... ERTS (') DRAINAGE LINE x- MAGN I TUDE 5.6 - 6·8 .-~RGNITUDE 6.0 - 6.9 -< .....ERCUR" ltliNG DiSTRICT K-~AGNITUDE • MERCURY INES 1.0 - 7,9 Abde I·Gawad & Si I verste i n 1973 .-~AONIrUDE ~·o - ~.4

FIG. 4. LANDSAT imagery of southern California and a plot of faults (after Abdel-Gawad and Silverstein, 1973),

1'0"""" W -1 1238 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1975

Other Earth hazards include the poten­ tial of earthquakes in many parts of the world. LANDSAT facilities for locating re­ gionallineaments have been used by inves­ tigators dealing with these hazards. M. Abdel-Gawad discovered evidence ofrecent movement along faults in southern California long considered to be inactiveJ Seismic hazards maps can be modified by inputs of this type provided by LANDSAT sensors. L. Gedney of the University of Alaska's Geophysical Institute constructed a mosaic of central Alaska using six LANDSAT im­ ages, clearly revealing the presence ofsets of "lineaments" (faults and fractures) which correlated well with the distribution ofshal­ low focus earthquake epicenters in the re­ o 25 MILES JI--~I---11 1004-21395 gion. Through these studies, an active leg of o 25 KILOMETERS the Denali fault was found to lie close to a bridge site over the Yukon River, and the FIG. 5. Lake orientation and associated geophysical lineations on the Alaskan arctic proposed route of the Alaskan oil pipeline. coastal plain (after Lathram et aI., 1973). Updated seismic data coupled with LAND­ SAT imagery will enable planners to modify their route selections as necessary. (NE Texas and SW Oklahoma) with known Perhaps less catastrophic but equally dev­ producing oil fields. Correlation exceeded 85 astating in the long term is the problem of per cent, and led the investigators to soil erosion. Morrison ofthe U. S. Geological hypothesize that these surface anomalies Survey dealt with regions ofaccelerated ero­ were the result ofvolatile components ofthe sion in southern Arizona. Present erosion petroleum reservoirs migrating to the sur­ damage was monitored by LANDSAT, flood­ face. Whether this phenomenon is a conse­ ing and floodwater recession observed, and quence of well drilling or is a natural occur­ an erosion-susceptibility map constructed as rence remains to be proven. an aid to future development. LANDSAT programs have made signifi­ EARTH HAZARDS: MONITORING AND SURVEYS cant contributions to many subspecialities Geologic hazards present a direct threat to within geology. Some of these contributions society in several familiar ways. The catas­ have already been felt in terms of corrected trophic result of earthquakes and volcanic maps and a more accurate awareness of pre­ eruptions, and the less spectacular but vailing seismic hazards. equally devastating effects of erosion and Some will be felt in the future, where the flooding can be monitored and better under­ promise of undiscovered mineral and pe­ stood through the synoptic and repetitive troleum deposits can be fulfilled through overview provided by LANDSAT 1 and 2. computer enhancement of LANDSAT data LANDSAT investigators have successfully combined with visual interpretation and used orbital imagery to inventory, monitor, supporting ground truth. and even forewarn of potential geologic Data collected by LANDSAT's sensors can catastrophes. Among these are USGS provide a wealth of information useful for geologists Eaton and Ward, who used solving the problems facing man as he tries to LANDSAT to relay information from a series live in harmony with his environment. Only of data collection platforms emplaced on ac­ thoughtful interpretation of the data, sup­ tive, potentially eruptive volcanoes in Alaska plemented by the technology of modern and Central America. DCP instrumentation computers, will enable him to maximize the consisted ofseismic event counters and bore benefits "for all mankind." hole tiltmeters, both designed to relay data characteristic ofthe pre-eruptive phase ofthe REFERENCES volcano. The investigation proved successful Abdel-Gawad, M., and J. Silverstein, 1973, "ERTS when the volcano F'uego, in Guatemala, Applications in Earthquake Research and erupted with devastating force shortly after Mineral Exploration in California," information relayed from the DCP indicated Symposium on Significant Results Obtained it would. from the Earth Resources Technology LANDSAT DATA: A NEW PERSPECTIVE FOR GEOLOGY 1239

Satellite-l, Vol. I Technical Presentations p. rains of New York State," Symposium on Sig­ 433-450 nificant Results Obtained from the Earth Re­ Bechtold, 1., M. Liggett, and J. Childs, 1973, "Re­ sources Technology Satellite-l, Vol. I, Tech­ gional Tectonic Control ofTertiary Mineraliza­ nical Presentations p. 223-230 tion, and Recent Faulting in the Southern Jensen, M., 1973, "Geology ofUtah and Nevada by Basin and Range Province, an Application of ERTS-I Imagery," Symposium on Significant ERTS-I Data," Symposium on Significant Re­ Results Obtained from the Earth Resources sults Obtained from the Earth Resources Technology Satellite-l Vol. I, Technical Pre­ Technology Satellite-l, Vol. I, Technical Pre­ sentations p. 247-256 sentations p. 425-432 Lathram, E., Tailleur, I., Patton, W. W., and Blodget, H. W., and A. T. Anderson, 1973, "A Fischer, W. A., 1973, "Preliminary Geologic Comparison ofGemini and ERTS imagery ob­ Application of ERTS-I Imagery in Alaska", tained over Southern Morocco," Symposium Symposium on Significant Results Obtained on Significant Results Obtained from the from the Earth Resources Technology Satel­ Earth Resources Technology Satellite-l, Vol. lite 1, Vol. I, NASNGoddard Space Flight I Technical Presentations p. 265-272 Center, Greenbelt, Md. p. 257-262 Collins, R. J., McCown, F. P., Stonis, L. P., and Petzel, G., 1973, "An evaluation of the suita­ Morrison, R B., and M. E. Cooley, 1973, "Applica­ bility of ERTS data for the purposes of pe­ tion of ERTS-I Multispectral Imagery to troleum exploration", presentation G-17, Third Monitoring the Present Episode of Acceler­ ated Erosion in Southern Arizona," ERTS Symposium, December 10-14, 1973 Symposium on Significant Results Obtained Gedney, L. D., and J. D. Van Wormer, 1973, from the Earth Resources Technology "Some aspects ofactive tectonism in Alaska as Satellite-l, Vol. I, Technical Presentation p. seen on ERTS-I imagery," Symposium on 283-290 Significant Results Obtained from Earth Re­ sources Technology Satellite-l, Vol. I, Tech­ Rich, E. 1., 1973, "Relation of ERTS-I detected nical Presentation p. 451-458 geologic structure to know economic ore de­ posits", Symposium on Significant Results Goetz, A. F. H., F. Billingsley, D. Elston, 1. Luc­ Obtained from the Earth Resources Technol­ chitta, and E. Shoemaker, 1973, "Preliminary ogy Satellite-l, Vol. I, NASNGoddard Space geologic investigations in the Colorado Flight Center, Greenbelt, Maryland, p. Plateau using enhanced ERTS images," 395-402 Symposium on Significant Results Obtained from the Earth Resources Technology Viljoen, R., 1973, "ERTS-I Imagery as an aid to the Satellite-l, Vol. I, Technical Presentation p. understanding of the Regional Setting of Base 403-411 Metal Deposits in the North West Cape Prov­ Gold, D. P., R Parizek, and S. Alexander, 1973, ince, South Africa," Symposium on Signifi­ "Analysis and Application ofERTS-1 Data for cant Results Obtainedfrom the Earth Resources Regional Geological Mapping," Symposium Technology Satellite-l, Vol. I, Technical Pre­ on Significant Results Obtained from the sentations p. 797-806 Earth Resources Technology Satellite-l, Vol. Vincent, R, 1973, "Ratio Maps of Iron Ore De­ I Technical Presentations p. 231-246 posits, Atlantic City District, Wyoming," Houston, R S., R Marrs, R. Breckenridge, and D. Symposium on Significant Results Obtained Blackstone, Jr., 1973, "Application of the from the Earth Resources Technology ERTS System to the Study of Wyoming Re­ Satellite-l, Vol. I, Technical Presentations p. sources with Emphasis on the use of Basic 379-386 Data Products," Symposium on Significant Ward, P., J. Eaton, E. Endo, D. Harlow, D. Mar­ Results Obtained from the Earth Resources quez, and R. Allen, 1973, "Establishment, Technology Satellite-l, Vol. I Technical Pre­ Test and Evaluation of a Prototype Volcano sentations p. 595-620 Surveillance System," Symposium on Sig­ Isachsen, Y., R Fakundiny, and S. Forster, 1973, nificant Results Obtained from the Earth Re­ "Evaluation of ERTS-I Imagery for Geologi­ sources Technology Satellite-l, Vol. I, Tech­ cal sensing over the Diverse Geological Ter- nical Presentations p. 305-315

Notice

The listing of the Officers of Committees of the Society in the July 1975 Yearbook issue (Page 833) showed A. Trachsel as Chairman of the Publications Committee, whereas L. W. Swanson is, in fact, the Chairman of the Publications Committee.