Sherrod, David R., 2013, Database to accompany Geologic Map of Oldonyo Lengai (Oldoinyo Lengai) Volcano and Surroundings, Arusha Region, United Republic of Tanzania: Open-File Report 2013-1306, U.S. Geological Survey, Menlo Park, Calif..This is part of the following larger work.Online Links:
Sherrod, David R., Magitita, Masota M., and Kwelwa, Shimba, 2013, Geologic Map of Oldonyo Lengai (Oldoinyo Lengai) Volcano and Surroundings, Arusha Region, United Republic of Tanzania: Open-File Report 2013-1306, U.S. Geological Survey, Menlo Park, Calif..Online Links:
This is a Vector data set. It contains the following vector data types (SDTS terminology):
The horizontal datum used is Arc datum of 1960 (New [Arc] 1960).
The ellipsoid used is Clarke 1880.
The semi-major axis of the ellipsoid used is 6378249.145.
The flattening of the ellipsoid used is 1/293.465.
Sequential unique positive integers generated automatically
| Value | Definition |
|---|---|
| 1 | ow, Open water (Lake Natron) |
| 101 | Ql1, Younger Lake Natron deposits, Holocene |
| 102 | Ql2, Lacustrine deposits perched by debris-avalanche deposits, Holocene? and Pleistocene |
| 103 | Ql3, Older Lake Natron deposits, Pleistocene |
| 200 | Qa1, Young alluvium, Holocene |
| 201 | Qa1-stipple, Young alluvium rich in angular to subangular blocks, Holocene |
| 202 | Qa2, Alluvium of areas rarely alluviated in past 200�2,000 years or more, Holocene |
| 203 | Qa3, Perched sand and gravel, Pleistocene |
| 204 | Qa4, Gelai sandstone and cobble veneer, Pleistocene |
| 205 | Qa5, Pebbly sandstone of high erosional surface, Pleistocene |
| 301 | Qsd, Sand dune, Holocene |
| 401 | Qls, Landslide deposit, Holocene or Pleistocene |
| 1051 | Qoda1, Debris-avalanche deposits filling modern drainage and banked against midslope cone, Holocene or Pleistocene |
| 1052 | Qoda2, Debris-avalanche deposits on east-northeast flank, Holocene or Pleistocene |
| 1053 | Qoda3, Debris-avalanche deposits on north-northeast flank, Holocene or Pleistocene |
| 1054 | Qoda4, Debris-avalanche deposits on south and southeast flanks, Holocene or Pleistocene |
| 1055 | Qoda5, Main avalanche sheet, Pleistocene |
| 1056 | Qoda6, Blocks in ancestral lake deposits, Pleistocene |
| 1101 | Qot, Tephra, Holocene and Pleistocene |
| 1102 | Qol, Mica-rich lahars, Holocene |
| 1201 | Qom, Main-cone volcaniclastic rocks and lava flows, Holocene and Pleistocene |
| 1202 | Qom-stipple, Pyroclastic-flow(? deposits of 2007�08, Holocene |
| 1203 | Qoml, Lava flows, Holocene and Pleistocene |
| 1211 | Qomlc, Carbonatite lava flows, Holocene |
| 1212 | Qomlu, Nephelinite of upper flanks, Holocene or Pleistocene |
| 1213 | Qomlp, Phonolite lava flow on lower east-southeast flank, Pleistocene |
| 1221 | Qomnc, Nasira tephra cones and spatter mounds, Holocene |
| 1222 | Qomnl, Nasira lava flows, Holocene |
| 1230 | Qomv, Flank vent deposits, Holocene? and Pleistocene |
| 1231 | Qomv?, Likely buried vent deposits on basis of circular or semicircular landforms, Holocene? and Pleistocene |
| 1250 | Qomc, Central-crater beds, Pleistocene |
| 2001 | Qnc, Natron-Engaruka tephra cones, Holocene? and Pleistocene |
| 2021 | Qnl, Natron-Engaruka lava flows, Pleistocene |
| 2031 | Qntr, Natron-Engaruka tuff rings, Pleistocene |
| 2041 | Qnet, Natron-Engaruka extensive tuff, Pleistocene |
| 2051 | Qpne, Phonolite lava flow 10 km northeast of summit, Pleistocene |
| 3010 | Qvg, Volcanic rocks of Gelai volcano, Pleistocene |
| 3020 | Qvk, Volcanic rocks of Kerimasi volcano, Pleistocene |
| 3030 | Qsk, Sekenge tuff ring deposits, Pleistocene |
| 3100 | Qbs, Basaltic sedimentary strata, Pleistocene |
| 3201 | QTel, Volcanic rocks of the Natron escarpment, lava flows, Pleistocene and Pliocene |
| 3211 | QTev, Volcanic rocks of the Natron escarpment, vent deposits, Pleistocene and Pliocene |
| 3251 | Tek, Lava of Endukai Kiti, Pliocene |
| 3301 | Tmc, Mosonik conglomerate, Pleistocene or Pliocene |
| 3311 | Tmv, Mosonik volcanic rocks, Pliocene or Miocene |
| 4001 | Qtse, Tuff and sandstone atop escarpment, Pleistocene |
| 4011 | Qmiu, Moinik Formation, upper tuff, Pleistocene |
| 4012 | Qmin, Moinik Formation, nephelinite lava flow, Pleistocene |
| 4013 | Qmic, Moinik Formation, claystone and tuff, Pleistocene |
| 5011 | Qh, Humbu Formation, Pleistocene |
| 5012 | Qhl, Humbu Formation, interbedded lava flows, Pleistocene |
| 5021 | Tnnm, Nephelinite lava north of Mosonik volcano, Pliocene |
| 6011 | Tsh, Sambu and Hajaro Basalts, Pliocene |
| Value | Definition |
|---|---|
| Alphanumeric text string with 1-to-1 correspondence to Attribute_Label Strat_code defined and enumerated separately previously in this metadata document | Character string derived from age and stratigraphic name of geologic units including query (?) for some labels to indicate uncertain age assignment of geologic unit |
| Value | Definition |
|---|---|
| Text string with 1-to-1 correspondence to Attribute_Label Strat_code defined and enumerated separately previously in this metadata document | Random-length character string showing formal or informal stratigraphic name, with formal names referable to publications cited in text |
| Value | Definition |
|---|---|
| Text string | Compiled in accompanying table |
| Value | Definition |
|---|---|
| Isaac, 1967 | Isaac, 1967 |
| Kervyn_etal_2008_fig03 | Kervyn and others, 2008, their figure 3 |
| This map | D.R. Sherrod, M.M. Magigita, and Kwelwa, Shimba, unpublished mapping of Mosonik and Oldonyo Lengai quadrangles |
Sequential unique positive integers generated automatically
| Value | Definition |
|---|---|
| 10 | Contact precisely or approximately located; boundary between adjacent stratigraphic units sufficiently close that position has been determined by field work to within 50 m on the ground (1.0 mm at 1:50,000 scale) |
| 11 | Contact inferred, approximately located; boundary drawn arbitrarily using aerial photography to demarcate geologic or volcanic feature with confidence that position lies within 200 m on the ground |
| 12 | Contact concealed; boundary between adjacent stratigraphic buried by younger volcanogenic or sedimentary deposits but probably located within 100 m on the ground |
| 15 | Contact internal; boundary between similar deposits within same stratigraphic unit but separable by geomorphic or other features determined by field work to within 50 m on the ground (1.0 mm at 1:50,000 scale) |
| 19 | Contact, scratch; no contact shown where stratigraphic unit extends beyond area of mapping but within area of map to indicate limits of knowledge |
Sequential unique positive integers generated automatically
Sequential unique positive integers generated automatically
| Value | Definition |
|---|---|
| 21 | Normal fault, well located; fault exposed or displaced stratigraphic units sufficiently close that position has been determined by field work to within 50 m on the ground (1.0 mm at 1:50,000 scale) |
| 22 | Normal fault, approximately located; ground surface morphology sufficiently distinct that fault may be traced as escarpment on air photos or topographic map with confidence that position lies within 50 m on the ground (1.0 mm at 1:50,000 scale) |
| 23 | Normal fault, inferred; geologic relations or ground surface morphology suggest fault present but not exposed and too uncertain to determine position closer than 100 m with confidence (2 mm at 1:50,000 scale) |
| 24 | Normal fault, concealed; trace of fault concealed by younger stratigraphic unit; positional accuracy uncertain but within 2 mm at 1:50,000 (100 m on the ground) and commonly within 1.0 mm (50 m on the ground) |
| 31 | Gaping crack, well located; ground crack with no vertical separation; may grade into normal fault along strike.; positional accuracy within 50 m on the ground (1.0 mm at 1:50,000 scale) |
| 34 | Lineament of uncertain origin; feature, mapped on air photos , most likely resulting from faults or ground cracks but not field checked |
| 35 | Lineament of liquefaction origin; not gaping crack but has pebbly sand layer (sand boil?) associated with it |
| Value | Definition |
|---|---|
| text string | 50 or fewer characters comprising known words |
| Value | Definition |
|---|---|
| text string | Holocene |
| text string | Pleistocene |
| text string | Quaternary |
| Value | Definition |
|---|---|
| E | Broadly east-side down |
| W | Broadly west-side down |
| N | Broadly north-side down |
| S | Broadly south-side down |
| O | no vertical displacement on gaping crack |
| n.d. | Not determined for lineaments |
| n.a. | Not applicable for subsidence pits whose boundary faults encircle the subsided core |
Sequential unique positive integers generated automatically
Sequential unique positive integers generated automatically
| Value | Definition |
|---|---|
| Lobate snout | Outer boundary of topographically high ground that corresponds to downslope limit of debris flow deposit |
| Fan margin | Boundary of upslope-narrowing alluvial fan, some of which probably mark past escavations by debris avalanche process |
| Levee edge | Boundary down topographic slope corresponding to lateral margin of debris-flow deposit |
| Isolated spur | Apex showing sector of volcano that now stands topographically high compared to adjacent fan area |
| Ridge-furrow topography | Crests of convex-downward ridges formed by flow of viscous lava |
Sequential unique positive integers generated automatically
| Value | Definition |
|---|---|
| 1 | Machine-graded main access road |
| 2 | Vehicle track, varies with weather; may be graded periodically |
| 3 | Vehicle track, unmaintained; trace across flood plain may be obliterated completely during heavy rain |
| 4 | Foot and stock path, commonly well established |
| 5 | Graded airstrip |
Sequential unique positive integers generated automatically
| Value | Definition |
|---|---|
| 200 | Contours with meter altitude 600, 800, 1000, and so on |
| 100 | Contours with meter altitude 700, 900, 1100, and so on |
| 40 | Contours with meter altitude 640, 680, 720, 760, 840, 880, 920, 960, 1040, and so on |
| 0 | All contours not assigned a previously stated Index value |
Sequential unique positive integers generated automatically
| Value | Definition |
|---|---|
| NE | Northeast |
| E | East (strike 000) |
| SE | Southeast |
| S | South (strike 090) |
| SW | Southwest |
| W | West (strike 180) |
| NW | Northwest |
| N | North (strike 270) |
| flat | flat-lying bed, strike reported as 000 |
| vert | Vertically oriented, dip = 90, no dip quadrant |
Sequential unique positive integers generated automatically
Sequential unique positive integers generated automatically
Sequential unique positive integers generated automatically
Sequential unique positive integers generated automatically
| Value | Definition |
|---|---|
| Phonolite | Phonolite |
| Phon-neph | Rock near the boundary between phonolite and nephelinite |
| CWN | Combeite-wollastonite nephelinite |
| Mel-CWN | Rock near the boundary between melilitite and combeite-wollastonite nephelinite |
| Value | Definition |
|---|---|
| 1 | Sample from debris-avalanche deposits spawned by Oldonyo Lengai |
| 2 | Sample from fallout tephra or scoria from Oldonyo Lengai |
| 3 | Sample from silicate lava flow from Oldonyo Lengai |
| 4 | Sample from Nasira cones and lava flows, northflank of Oldonyo Lengai |
| 5 | Sample from parasitic cones on Oldonyo Lengai but probably part of Natron-Engaruka volcanic field |
| 6 | Sample from rocks of Natron-Engaruka volcanic field or from Gelai volcano |
| 7 | Sample from volcanic rocks of the escarpment, Endukai Kiti |
| 8 | Sample from volcanic rocks of the escarpment, Mosonik volcano |
Sequential unique positive integers generated automatically
| Value | Definition |
|---|---|
| Mosonik topographic quadrangle map | 1990 edition of sheet 39/2 |
| Oldonyo Lengai topographic quadrangle map | 1990 edition of sheet 39/4 |
| Local usage | Name reported by village elders, Engare Sero village |
| Dawson, 1962 | Name appearing in 1962 publication by J.B. Dawson |
| Keller et al., 2006 | Name appearing in 2006 publication by J. Keller and colleagues |
Sources of mapping are indicated on geologic map sheet of USGS Open-File Report 2013-1306 (Sherrod and others, 2013). Acknowledgment of other data is found in the map's description of map units and explanatory pamphlet.
(650) 329-5057 (voice)
(650) 329-5051 (FAX)
This database was constructed in order to assess volcano and earthquake hazards in the area surrounding Oldonyo Lengai (Oldoinyo Lengai) volcano.
Sherrod, D.R., Magigita, M.M., and Kwelwa, S., 2013, Geologic Map of Oldonyo Lengai (Oldoinyo Lengai) Volcano and Surroundings, Arusha Region, United Republic of Tanzania: Open-File Report 2013-1306, U.S. Geological Survey, Reston, Va..Online Links:
Dawson, J.B., 1962, The geology of Oldoinyo Lengai:,.
Isaac, G.L., 1967, The stratigraphy of the Peninj Group�early middle Pleistocene formations west of Lake Natron, Tanzania:,.
Keller, J., Zaitsev, A.N., Wiedenmann, D., 2006, Primary magmas at Oldoinyo Lengai: the role of olivine melilitites:,.
Kervyn, M., Ernst, G.G.J., Klaudius, J., Keller, J., Mbede, E., Jacobs, P., 2008, Remote sensing study of sector collapses and debris avalanche deposits at Oldoinyo Lengai and Kerimasi volcanoes:,.
Klaudius, J., Keller, J., 2006, Peralkaline silicate lavas at Oldoinyo Lengai, Tanzania:,.
Tanzania Ministry of Lands, Housing, and Urban Development, 1990, Mosonik:,.
Tanzania Ministry of Lands, Housing, and Urban Development, 1990, Oldonyo Lengai:,.
Person who carried out this activity:
(Name), (650) 329-XXXX (voice)
(650) 329-5051 (FAX)
(Name), XXXX@usgs.gov
Good. Feature attributes were entered by David R. Sherrod, reviewed by Donald A. Swanson, Keith A. Howard, and Evan E. Thoms, then later checked by USGS senior author Sherrod. The attributes consist of text identifiers and numeric codes for each geologic unit or type of geologic feature, and they determine how each feature is colored or symbolized. For purposes of checking attribute accuracy, a color plot was visually compared to the geologists' original compilation. Discrepancies between the digital geospatial dataset and the original analog compilation were corrected as needed. Machine-created listings of unique attribute values were used to identify spelling errors or other inconsistencies, and corrections were made as needed.
Geologic source data were compiled as photogeologic map using using Kern PG-2 photogrammetric plotter. Then during field phase of mapping, photo map was checked and additional data added to it. Consequently, data have a horizontal positional accuracy corresponding to 1 mm at the scale of the large-scale map, or ranging from plus-or-minus 15 to 50 meters on the ground. An overall accuracy is reported here as within 50 meters on the ground. Inaccuracies associated with the 15-minute topographic maps themselves, which likely are within U.S. National Map Accuracy Standards, will be far less than the stated accuracy of the 50,000-scale geologic map.
No vertical positional data recorded in polygon or arc (chain-node) geologic coverages. Hypsometric coverage derived by manual tracing of topographic contours from 1:50,000-scale base maps. Databases for geochemical and radiometric samples report orthometric altitude, which was estimated by inspection of plotted points on digital raster graphs of 1:50,000-scale topographic quadrangles. Accuracy is no better than one-half the contour interval, which ranges from 20 to 40 m.
This dataset is intended to describe completely the igneous and sedimentary products and structural features at 1:50,000 scale. Omitted in most places are those features whose visual resolution requires a substantially larger scale of presentation.
Polygon and arc (chain-node) topology present in MapInfo coverages. Other coverages are point or annotation; neither they nor any supplied raster images require topologic relations. Polygon coverages were tested topologically using Mapinfo software, with no errors found for duplicate nodes, overlaps, or gaps.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
- Uses of this digital geologic map should not violate the spatial resolution of the data. Although the digital form of the data removes the constraint imposed by the scale of a paper map, the detail and accuracy inherent in map scale are also present in the digital data. This map was compiled and edited for scale 1:50,000, so no higher-resolution information is present in the dataset. Plotting at scales larger than 1:50,000 will not yield greater real detail, although it may reveal fine-scale irregularities below the intended resolution of the database. Similarly, where this database is used in combination with other data of higher resolution, the resolution of the combined output will be limited by the lower resolution of these data. Acknowledgment of the U.S. Geological Survey and the Geological Survey of Tanzania would be appreciated in products derived from these data. There are no expressed warranties associated with the release of this database. Specifically, no warranty is made that the GIS data or any subsequent updates will be error free, and no warranty is made regarding the positional or thematic accuracy of the GIS data. The GIS data and any features they depict do not represent or confer any legal rights, privileges, benefits, boundaries, or claims of any kind. The U.S. Geological Survey and the Geological Survey of Tanzania encourages GIS data users to verify the suitability of the data before use. Please report any discrepancies or errors to Michael Diggles, Publications Service Center, 345 Middlefield Road, Menlo Park, CA 94025. Phone: (650) 329-5404; email: mdiggles@usgs.gov.
(303) 202-4200 (voice)
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infoservices@usgs.gov
U.S. Geological Survey Open-File Report Series 2013-1306
This database has been approved for release and publication by the Director of the U.S. Geological Survey (USGS). Although this database has been subjected to some review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
| Data format: | MapInfo native coverages (TAB files) and export-format (.e00 and shp) files convertible to ArcInfo coverages, and related geologic-map descriptive data and files for generating plots. (version MapInfo version 8.5) Size: #### |
|---|
| Data format: | Export-format (shp) files convertible to ArcInfo coverages, and related geologic-map descriptive data and files for generating plots. in format shp (version MapInfo version 8.5) Size: #### |
|---|---|
| Network links: |
http://pubs.usgs.gov/of/2013/1306/ |
| Media you can order: |
CD-ROM
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(360) 993-8900 (voice)
(360) 993-8980 (FAX)
dsherrod@usgs.gov