Research Article| August 01, 2004 Global geologic context for rock types and surface alteration on Mars Michael B. Wyatt; Michael B. Wyatt 1Department of Geological Sciences, Arizona State University, Tempe, Arizona 85251, USA Search for other works by this author on: GSW Google Scholar Harry Y. McSween, Jr.; Harry Y. McSween, Jr. 2Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee 37996, USA Search for other works by this author on: GSW Google Scholar Kenneth L. Tanaka; Kenneth L. Tanaka 3U.S. Geological Survey, Flagstaff, Arizona 86001, USA Search for other works by this author on: GSW Google Scholar James W. Head, III James W. Head, III 4Department of Geological Sciences, Brown University, Providence, Rhode Island 02912, USA Search for other works by this author on: GSW Google Scholar Geology (2004) 32 (8): 645–648. https://doi.org/10.1130/G20527.1 Article history received: 02 Feb 2004 rev-recd: 09 Apr 2004 accepted: 16 Apr 2004 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Michael B. Wyatt, Harry Y. McSween, Kenneth L. Tanaka, James W. Head; Global geologic context for rock types and surface alteration on Mars. Geology 2004;; 32 (8): 645–648. doi: https://doi.org/10.1130/G20527.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Petrologic interpretations of thermal emission spectra from Mars orbiting spacecraft indicate the widespread occurrence of surfaces having basaltic and either andesitic or partly altered basalt compositions. Global concentration of ice-rich mantle deposits and near-surface ice at middle to high latitudes and their spatial correlation with andesitic or partly altered basalt materials favor the alteration hypothesis. We propose the formation of these units through limited chemical weathering from basalt interactions with icy mantles deposited during periods of high obliquity. Alteration of sediments in the northern lowlands depocenter may have been enhanced by temporary standing bodies of water and ice. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Research Article| February 01, 1986 Migration of volcanism in the San Francisco volcanic field, Arizona KENNETH L. TANAKA; KENNETH L. TANAKA 1U.S. Geological Survey, 2255 North Gemini Drive, Flagstaff, Arizona 86001 Search for other works by this author on: GSW Google Scholar EUGENE M. SHOEMAKER; EUGENE M. SHOEMAKER 1U.S. Geological Survey, 2255 North Gemini Drive, Flagstaff, Arizona 86001 Search for other works by this author on: GSW Google Scholar GEORGE E. ULRICH; GEORGE E. ULRICH 2U.S. Geological Survey, Hawaiian Volcano Observatory, Hawaii National Park, Hawaii 96718 Search for other works by this author on: GSW Google Scholar EDWARD W. WOLFE EDWARD W. WOLFE 2U.S. Geological Survey, Hawaiian Volcano Observatory, Hawaii National Park, Hawaii 96718 Search for other works by this author on: GSW Google Scholar Author and Article Information KENNETH L. TANAKA 1U.S. Geological Survey, 2255 North Gemini Drive, Flagstaff, Arizona 86001 EUGENE M. SHOEMAKER 1U.S. Geological Survey, 2255 North Gemini Drive, Flagstaff, Arizona 86001 GEORGE E. ULRICH 2U.S. Geological Survey, Hawaiian Volcano Observatory, Hawaii National Park, Hawaii 96718 EDWARD W. WOLFE 2U.S. Geological Survey, Hawaiian Volcano Observatory, Hawaii National Park, Hawaii 96718 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1986) 97 (2): 129–141. https://doi.org/10.1130/0016-7606(1986)97<129:MOVITS>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation KENNETH L. TANAKA, EUGENE M. SHOEMAKER, GEORGE E. ULRICH, EDWARD W. WOLFE; Migration of volcanism in the San Francisco volcanic field, Arizona. GSA Bulletin 1986;; 97 (2): 129–141. doi: https://doi.org/10.1130/0016-7606(1986)97<129:MOVITS>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The remanent magnetization of volcanic rocks has been determined at 650 sites in the San Francisco volcanic field in the southern part of the Colorado Plateau. The polarity of remanent magnetization—combined with K-Ar age determinations, spatial and petrographic associations, stratigraphic relations, and state of preservation of the cinder cones—provides a basis for assignment to known magnetic polarity epochs of 610 mafic vents and >100 intermediate to silicic flows, flow sequences, and vents. The age assignments for basaltic rocks include 243 Brunhes (<0.73 Ma) vents, 220 Matuyama (0.73 to 2.48 Ma) vents, and 147 pre-Matuyama (2.48 to about 5.0 Ma) vents. Basaltic volcanism migrated northeastward before Matuyama time at a rate of ∼1.2 cm/yr and eastward (S87° ± 5°E) over the past 2.5 m.y. at a rate of 2.9 ± 0.3 cm/yr. Concomitant acceleration in total magma production (from 75 to 1,400 × 10−6 km3/yr) and frequency of basaltic eruptions (from 1 per 17,000 yr to 1 per 3,000 yr) occurred between 5 and 0.25 Ma. For the past 0.25 m.y., magma production (∼180 × 10−6 km3/yr) and perhaps eruption frequency have decreased. This evolutionary sequence, coupled with the lead and strontium-isotopic composition of the rocks, can be explained by magmatism caused by shear heating at the base of the lithosphere. We propose that this eastward drift of volcanic activity represents absolute westward motion of the North American plate. Our model is in agreement with a model in which the African plate is fixed to the deep mantle. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
The NASA Mars Exploration Rover (MER) Project has been considering a landing‐site ellipse designated EP78B2 in southeastern Utopia Planitia, southwest of Elysium Mons. The site appears to be relatively safe for a MER landing site because of its predicted low wind velocities in mesoscale atmospheric circulation models and its low surface roughness at various scales as indicated by topographic and imaging data sets. Previously, the site's surface rocks have been interpreted to be marine sediments or lava flows. In addition, we suggest that Late Noachian to Early Hesperian collapse and mass wasting of Noachian highland rocks contributed to the deposition of detritus in the area of the ellipse. Furthermore, we document partial Late Hesperian to Early Amazonian resurfacing of the ellipse by flows and vents that may be of mud or silicate volcanic origin. A rover investigation of the Utopia landing site using the MER Athena instrument package might address some fundamental aspects of Martian geologic evolution, such as climate change, hydrologic evolution, and magmatic and tectonic history.
Geologic mapping of the northern plains of Mars, based on Mars Orbiter Laser Altimeter topography and Viking and Mars Orbiter Camera images, reveals new insights into geologic processes and events in this region during the Hesperian and Amazonian Periods. We propose four successive stages of lowland resurfacing likely related to the activity of near‐surface volatiles commencing at the highland‐lowland boundary (HLB) and progressing to lower topographic levels as follows (highest elevations indicated): Stage 1, upper boundary plains, Early Hesperian, <−2.0 to −2.9 km; Stage 2, lower boundary plains and outflow channel dissection, Late Hesperian, <−2.7 to −4.0 km; Stage 3, Vastitas Borealis Formation (VBF) surface, Late Hesperian to Early Amazonian, <−3.1 to −4.1 km; and Stage 4, local chaos zones, Early Amazonian, <−3.8 to −5.0 km. At Acidalia Mensa, Stage 2 and 3 levels may be lower (<−4.4 and −4.8 km, respectively). Contractional ridges form the dominant structure in the plains and developed from near the end of the Early Hesperian to the Early Amazonian. Geomorphic evidence for a northern‐plains‐filling ocean during Stage 2 is absent because one did not form or its evidence was destroyed by Stage 3 resurfacing. Remnants of possible Amazonian dust mantles occur on top of the VBF. The north polar layered deposits appear to be made up of an up to kilometer‐thick lower sequence of sandy layers Early to Middle Amazonian in age overlain by Late Amazonian ice‐rich dust layers; both units appear to have outliers, suggesting that they once were more extensive.
Many of the mountains in the rugged highland terrain of the Phaethontis and Thaumasia quadrangles are believed to be of volcanic origin. Those provisionally mapped as volcanoes have diagnostic characteristics such as lobate flow fronts around their bases, depressed central areas, or have massive, bulbous accumulations of material of no determinable origin other than volcanic. Most of the volcanoes are younger than materials forming the highlands but are older than early lava flows from Arsia Mons. Many are aligned along older fault and ridge systems that are transverse to the more recent and prominent faults transecting the region. The older faults are generally buried by plains lava flows but their traces are visible in several places in the highlands. These faults are relatively short in length.
A detailed planetwide stratigraphy for Mars has been developed from global mapping based on Viking images and crater counting of geologic units. The original Noachian, Hesperian, and Amazonian Systems are divided into eight series corresponding to stratigraphic referents. Characteristic crater densities and material referents of each series are (1) Lower Noachian [N(16)] (number of craters > 16 km in diameter per 10 6 km 2 ) > 200] basement material; (2) Middle Noachian [N(16) = 100–200] cratered terrain material; (3) Upper Noachian [N(16) = 25–100; N(5) = 200–400] intercrater plains material; (4) Lower Hesperian [N(5) = 125–200] ridged plains material; (5) Upper Hesperian [N(5) = 67–125; N(2) = 400–750] complex plains material; (6) Lower Amazonian [N(2) = 150–400] smooth plains material in southern Acidalia Planitia; (7) Middle Amazonian [N(2) = 40–150] lava flows in Amazonis Planitia; and (8) Upper Amazonian [N(2) < 40] flood‐plain material in southern Elysium Planitia. Correlations between various crater size‐frequency distributions of highland materials on the moon and Mars suggest that rocks of the Middle Noachian Series are about 3.92–3.85 b.y. old. Stratigraphic ages compiled for units and features of various origins show that volcanism, tectonism, and meteorite bombardment have generally decreased through Mars' geologic history. In recent time, surficial processes have dominated the formation and modification of rock units. The overall stratigraphy of Mars is complex, however, because of temporal and spatial variations in geologic activity.
A series of postulated ignimbrite units is mapped in the Amazonis, Memnonia, and Aeolis quadrangles of Mars. The units cover about 2.2×10 6 km 2 within a broad but discontinuous and irregular belt trending east‐west along the highland‐lowland boundary. The ignimbrites overlie parts of the western and southern aureole materials of Olympus Mons but are embayed in places by the lava plains of the lowlands. Stratigraphic relations between the basalt flows from the Tharsis Montes region and the ignimbrites are not clearly defined; crater counts suggest that the younger ignimbrites postdate the lava flows. Crater counts per square kilometer for the ignimbrites range from 7.29±1.95×10 −4 to 6.36±2.01×10 −5 for craters larger than 1 km in diameter. The ignimbrite materials form thick (≥100 m), extensive, relatively flat sheets that are smooth to grooved or gently undulating. Grooved surfaces appear to be yardangs and, in most places, are not alined with prevailing wind directions. The seven mapped ignimbrite units are characterized by morphologic expression, stratigraphic position, and crater counts. Similarities to ignimbrites in the Pancake Range of central Nevada include (1) rounded patches of smooth, high‐albedo, nonwelded material superposed on jointed, low‐albedo, welded material, (2) local complementary joint sets in welded materials, and (3) thick flow sheets of great areal extent that follow but subdue underlying topography. Four major eruptive centers occur in areas where units are thickest and where a dominant, NNW‐SSE structural trend is expressed locally by unit margins, elongate collapse features, and normal faulting. A minimum volume of 3.85×10 6 km 3 for the deposits has been calculated from thickness estimates based on shadow measurements and crater rim height relations.
We present remanent magnetizations determined for 657 sites of volcanic rocks in the San Francisco volcanic field, an area of about 4,800 km 2 in the southern part of the Colorado Plateau.The field includes scattered basaltic cinder cones and flows as well as silicic and intermediate rocks mostly in voluminous eruptive centers.About 90 percent of the sites yielded clear polarity determinations; the remainder have scattered data (a 95 > 40°) or peculiar directions.Comprehensive stratigraphic controls-paleomagnetic polarity data, K-Ar and other absolute-age determinations, superposition relations, and lithologic associations-and state of preservation of the cinder cones provide a basis for age assignments of 503 separate eruptions related to basaltic vents and flows and 80 silicic to intermediate domes, flows, and flow sequences.The eruptions are assigned to three magnetopolarity sequences (polarity chronozones): the pre-Matuyama Chronozone (about 5.0 to 2.48 Ma), the Matuyama Reversed-Polarity Chronozone (2.48 to 0.73 Ma), and the Brunhes Normal-Polarity Chronozone (0.73 Ma to present).This stratigraphy documents a progression of volcanism, first to the northeast and then to the east: volcanic activity was centered along the Mesa Butte fault zone during pre-Matuyama and early Matuyama time and turned eastward through San Francisco Mountain during late Matuyama and Brunhes time.Site averages of magnetic vectors indicate that no appreciable crustal translations or rotations occurred in the field during eruptive activity.
Research Article| May 01, 2001 Huge, CO2-charged debris-flow deposit and tectonic sagging in the northern plains of Mars Kenneth L. Tanaka; Kenneth L. Tanaka 1U.S. Geological Survey, Flagstaff, Arizona 86001, USA Search for other works by this author on: GSW Google Scholar W. Bruce Banerdt; W. Bruce Banerdt 2Jet Propulsion Laboratory, Pasadena, California 91109, USA Search for other works by this author on: GSW Google Scholar Jeffrey S. Kargel; Jeffrey S. Kargel 3U.S. Geological Survey, Flagstaff, Arizona 86001, USA Search for other works by this author on: GSW Google Scholar Nick Hoffman Nick Hoffman 4La Trobe University, Bundoora, Victoria 3083, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information Kenneth L. Tanaka 1U.S. Geological Survey, Flagstaff, Arizona 86001, USA W. Bruce Banerdt 2Jet Propulsion Laboratory, Pasadena, California 91109, USA Jeffrey S. Kargel 3U.S. Geological Survey, Flagstaff, Arizona 86001, USA Nick Hoffman 4La Trobe University, Bundoora, Victoria 3083, Australia Publisher: Geological Society of America Received: 13 Sep 2000 Revision Received: 22 Jan 2001 Accepted: 31 Jan 2001 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2001) 29 (5): 427–430. https://doi.org/10.1130/0091-7613(2001)029<0427:HCCDFD>2.0.CO;2 Article history Received: 13 Sep 2000 Revision Received: 22 Jan 2001 Accepted: 31 Jan 2001 First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Kenneth L. Tanaka, W. Bruce Banerdt, Jeffrey S. Kargel, Nick Hoffman; Huge, CO2-charged debris-flow deposit and tectonic sagging in the northern plains of Mars. Geology 2001;; 29 (5): 427–430. doi: https://doi.org/10.1130/0091-7613(2001)029<0427:HCCDFD>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The northern plains of Mars contain a vast deposit, covering one-sixth of the planet, that apparently resulted in extensive lithospheric deformation. The center of the deposit may be as much as 2–3 km thick. The deposit has lobate margins consistent with the flow of fluidized debris for hundreds to thousands of kilometers derived from highland and high-plains sources. The deposit surface lowers inward by ∼900 m in places and is locally bordered by a bulge ∼300 m high. Similar deformation accompanied development of Pleistocene ice sheets on Earth. The lack of burial of a large inlier of older terrain and the response time of the mantle to the loading require that the deposit was emplaced in <1000 yr, assuming that the deposit was originally flat. We account for what may have been the largest catastrophic erosional and/or depositional event in solar system history by invoking pore-filling subsurface CO2 as an active agent in the processes of source-rock collapse and debris flow. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
