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Lawn Hill Platform and Leichhardt River Fault Trough measured stratigraphic section online GIS

Note: This metadata describes the dataset in accordance with the ANZLIC (Australia New Zealand Land Information Council) Core Metadata Guidelines Version 2.


Dataset citation

ANZLIC unique identifier: ANZCW0703005121

Title: Lawn Hill Platform and Leichhardt River Fault Trough measured stratigraphic section online GIS


Custodian

Custodian: Geoscience Australia

Jurisdiction: Australia


Description

Abstract:

This GIS web browser contains stratigraphic information (in PDF format) from the southern flank of the Murphy Inlier, Lawn Hill Platform and Leichhardt River Fault Trough in the Western Succession of the Mount Isa Block. The principal lithostratigraphic units covered by this dataset include the Surprise Creek Formation, Mount Isa and McNamara Groups. The images are pixilated versions of those contained on CD Records AGSO Record 1999/10, AGSO Record 1999/15, GA Record 2002/3. The data contained on the CD's is more comprehensive, at a better resolution and also contains cross sections that are not available over the web. No drill hole data is supplied in this viewer. The data compiled for this viewer was collected during the course of the NABRE, AMIRA P552 and pmd*CRC projects. The respective CD's also provide measured sections at different scales with slightly varying information available at 1:400, 1:1000, 1:2500 and 1:5000 scales. The information at each scale is slightly different. Plot files ready for printing also accompany the measured sections.

Each of the measured sections contains primary observational data (grainsize, lithology, bed thickness, sedimentary structure and gamma ray curve) map-based lithostratigraphic units as shown on the 1:100,000 geological sheets, interpreted facies and sequence stratigraphic surfaces.

Sections were measured using a Jacobs Staff and Abney Level and the rocks were marked in 1.5 m intervals of true thickness. Gamma ray data was collected at either 50 cm or 75 cm intervals of true thickness using hand-held Scintrex GRS 500 spectrometers that measured total gamma ray counts. A beryllium standard was used to calibrate each spectrometer. Each machine was calibrated at intervals of two to three hours. Each gamma reading was averaged over an interval of ten seconds.

ANZLIC search words:

  • GEOSCIENCES Geology Mapping
  • MINERALS Mapping

Spatial domain:

locality map

Geographic extent polygon: 136.3 -17.3, 141 -17.3, 141 -22.3, 136.3 -22.3, 136.3 -17.3,

Geographic bounding box:
North bounding latitude: -17.3 °
South bounding latitude: -22.3 °
East bounding longitude: 141 °
West bounding longitude: 136.3 °

Data currency

Beginning date: 2003-01-01

Ending date: Not Known


Dataset status

Progress: In Progress

Maintenance and update frequency: Not Known


Access

Stored data format:
DIGITAL - shp ArcView shape file ArcView Universal Transverse Mercator (UTM) AGD66

Access constraints:

Licence required.

Free Data Download

Data quality

Lineage:

GEOLOGY:

There are three steps relating to the initial data capture and upgrade to a high-level GIS: (i) Interpretation and creation of source maps; (ii) Data capture from source maps; (iii) Post-data capture upgrade.

(i) Geological maps are a depiction of information acquired from interpretation (mostly aerial photography), field observation, and subsequent investigation (eg sample analysis for age and rock-type determination). Some detail may have been generalised, re-positioned, or omitted from the primary data for cartographic purposes. Maps were compiled from unrectified photo overlays onto topographic bases supplied by the Commonwealth mapping authorities. Drainage and, other topographic features (eg fence lines) were used for spatial control of the geological data.

(ii) Data were captured from stable-base repromat used in the production of the hardcopy multi-colour geological maps. Initial acquisition was by high precision scanning. Resultant raster files were warped to fit digital graticules generated using Intergraph CAM software. Affine-1 warp was used, with the four corners of each tile forming tie points. Warped raster files were then vectorised and cleaned up using Abakos Provec and Scanfix software. Further interactive editing and additional capture of point data was carried out using MicroStation software. MicroStation vector data were plotted and visually checked. MicroStation vector data were translated to ArcInfo coverage format using in-house scripts and ESRIs IGDSARC utility. Attribute fields were populated using information from the printed maps and coverages were built for topology, checked and edited.

(iii) The original data are imported from export files into double precision ArcInfo coverages. Spatial processing and transformations on the data were done using ESRI's ArcInfo (version 7.2.1) GIS software.

ROAD NETWORK (National Geoscience Dataset):

This dataset (ANZCW0703002391) was compiled by Geoscience Australia staff from the original Digital Chart of the World VPF format dataset downloaded from the DCW website listed in the abstract. For information on the lineage of the original DCW (VPF format) datasets please view the Digital Chart of the World website listed in the abstract. The roads dataset was simplified so that only the towns relevant for the Online GIS were present.

Post-DCW lineage

The seperate DCW tiles NA11, UA11, QC32-33, QD31-33, QE31-33, QF31-33 and all the RC, RD, RE, RF, SC, SD, SE, SF, TC, TD, TE, TF, UC, UD, UE, UF, VC, VD, VE, VF, WC, WD, WE, WF, XC, XD, XE, XF, YC, YD, YE, YF, ZC, ZD, ZE and ZF were compiled into single covers based upon the separate DCW themes. The vegetation layer was not available for the Australian area.

The data was then attributed fully as the existing coverages were attributed in code which only made sense with the DCW Data Dictionary. The field names were changed to be clearer for example the field AEPTVAl was changed to Elevation. No cleaning of the data was necessary exept for the place names coverages where upper and mixed case place names existed in the DCW data these were all changed to mixed case.

Geoscience Australia compliant fields were added to the data at this stage: UFI and FEATURE with AGSO_CODE and DESC added to non-polygon themes.

This dataset is a subset of the transport coverage which was compiled from the original DCW railroad arc coverage, the road arc coverages, the transportation structure line coverage, the transportation structure point coverage and the aeronautical point coverage.

POPULATION CENTRES (National Geoscience Dataset):

The population centres dataset (ANZCW0703002389) was simplified so that only the towns relevant for the Online GIS were present.

See "More Metadata"

Positional accuracy:

GEOLOGY:

An accurate assessment of horizontal accuracy is not possible because the history of the original source information and subsequent revisions are not fully known. However a range of errors and/or anomalies were observed during construction of the dataset. These are possibly due to: (i) inaccurate topographic bases; (ii) spheroid or datum differences; and (iii) map production processes.

The error associated with delineation of geographic features and map production process is estimated at 0.5 mm at the respective map scale. Geological interpretation from the aerial photography was carried out at 1:25 000 scale, while data were digitised from the standard 1:100 000 geological map. Thus, the total estimated positional error due to map production process is about +/-125 m. However, positional accuracy for some of the edge-matched features at the tile boundary is estimated to be up to +/-300 m. This estimate should be interpreted in conjunction with the positional accuracy of the topographic base used in the interpretation of source data.

ROAD NETWORK & POPULATION CENTRES (National Geoscience Datasets):

Nominal Scale 1:1,000,000

Low to moderate accuracy due to highly variable source data and the vintage of this dataset.

Attribute accuracy:

MEASURED SECTIONS:

Each of the measured sections contains primary observational data (grainsize, lithology, bed thickness, sedimentary structure and gamma ray curve) map-based lithostratigraphic units as shown on the 1:100,000 geological sheets, interpreted facies and sequence stratigraphic surfaces.

Sections were measured using a Jacobs Staff and Abney Level and the rocks were marked in 1.5 m intervals of true thickness. Gamma ray data was collected at either 50 cm or 75 cm intervals of true thickness using hand-held Scintrex GRS 500 spectrometers that measured total gamma ray counts. A beryllium standard was used to calibrate each spectrometer. Each machine was calibrated at intervals of two to three hours. Each gamma reading was averaged over an interval of ten seconds.

Outcrop discontinuities prevented the collection of stratigraphic data in a line of continuous section. As a result most of the sections present in this data set comprise a series of segments combined to form a single composite section. The single sections were all measured within a radius of several kilometres of each other. Individual sections were spliced together at prominent marker beds (outcrop tracing of strata), or by the use of overlapping gamma ray curves in conjunction with facies descriptions. Section locations shown in the web browser depict the base of each composite section. Grid coordinates for the base each composite section can be found in the header block of the appropriate section.

GEOLOGY:

The geological maps used in this web browser depict the approximate position of supersequence boundaries. Not all the geology for the region has been included and only the geology relevant to the measured sections has been used. The supersequences provided are based on the most appropriate lithostratigraphic boundaries and no new geological polygons have been created. It should be noted that the Torpedo Creek and Warrina Park Quartzites have been placed in the Prize Supersequence. However, we acknowledge that due to mis-mapping of these sand bodies the Torpedo Creek and Warrina Park Quartzites from the basal part of the Gun Supersequence at some locations.

Attributes are mostly a representation of information on the source maps and should be viewed in that context - some of the information and/or interpretation is more than 20 years old and may be incorrect and/or outdated. Attributes are tile specific - for example the same geological unit on separate tiles may have different lithological descriptions, ages and possibly even names. This is a reflection of the knowledge and/or information available at the time of production of the source map. The Geological units were largely interpreted from colour aerial photographs at 1:25 000 scale. The interpretation was carried out in conjunction with numerous field observations and/or measurements, and sample collection and analysis. The reliability and field site location diagrams on the printed geological source maps provide some (basic) indication of the level of work undertaken. Most of the source maps have accompanying Explanatory Notes, which provide much more detail about the geology and interpretative work.

ROAD NETWORK & POPULATION CENTRES (National Geoscience Dataset):

Low to moderate accuracy due to highly variable source data and the vintage of this dataset.

Logical Consistency:

Data have been checked visually on plots and for topological consistency using in-house routines and ArcInfo GIS software. In addition, the upgrade of the data required passing on a number of rigorous validation tests. As much as possible, every effort has been made to ensure that the accuracy and standards of the source maps have been maintained.

Completeness:

Coverage: Because the geological maps are the only source for the data, not all attributes are complete for all elements or tiles. In some cases, for example the age, name and genealogy of stratigraphic units, information may be inconsistent between tiles. This is due to previous mismapping and miscorrelation of units.

Classification: Completeness and consistency of classification needs to be considered in the context of the time span of the source geological map and the highly interpretative nature of the discipline. Broadly similar classification and measurement techniques have been applied to geological map compilation for many years, however resultant data does reflect individual geologists ideas and preferences. The classification of boundaries and similar features (ranging from accurate, approximate, concealed, inferred) for example is not particularly consistent and therefore needs to be treated with caution.

Verification: There is no consistent record of the extent of field observation as opposed to airphoto interpretation. However the frequency of measured sites on maps, such as measurements of mesoscopic structures, is a reasonable indicator of field activity and/or verification. More information can be found in Explanatory Notes, which were produced in conjunction with the geological map.


Contact information

Contact organisation: Commonwealth of Australia (Geoscience Australia) (GA)
Contact position: Manager Client Services
Mail address: Cnr Jerrabomberra Ave and Hindmarsh Dr
Mail address: GPO Box 378
Locality: Canberra
State: ACT
Country: Australia
Postcode: 2601
Telephone: 02 6249 9966
Facsimile: 02 6249 9960
Electronic mail address: sales@ga.gov.au

Metadata information

Metadata date: 2013-03-08


Additional metadata

Metadata reference XHTML: http://www.ga.gov.au/meta/ANZCW0703005121.html

Metadata reference XML: http://www.ga.gov.au/meta/ANZCW0703005121.xml

This Online GIS contains the following datasets (all datasets presented in AGD66 datum)

Vector data:

The geological polygon layer is composed of 15 polygons that have had their internal geology dissolved.

pop_ptdd - line shapefile of the National Geology, National Geoscience Datasets

roadsdd - Polygon and line shapefile of the National Geology, National Geoscience Datasets

Data are unprojected from Universal Transverse Mercator (UTM) projection into geodetic coordinate system. Australian Geodetic Datum 1966 (AGD66). Spheroid, is the Australian National Thematic coverages were edge-matched with surrounding tiles, where data was available. While, in general, features at the coverage boundaries matched, sometimes it was necessary to carry out some interpretative work. In particular, where the discrepancy between two same arcs features at the adjoining tiles was less than 250 m, the nodes were snapped at half-distance from their original position. All this was completed for the Geology coverage ANZCW0703003759. This coverage was further simplified so that all the geolgical boundaries within the individual map tiles and all attributes within the same supersequence were dissolved. (The supersequence boundaries were identified during the NABRE and AMIRA P552 projects at Geoscience Australia.) As the geology was only used as a background layer for the online GIS so that people could spatially orient thenselves, dissoving the geology 1) reduced the file size for web delivery and 2) Ensured that no misinformation was added to the datasets.

For further information see metadata accompanying the GIS data.

Authors:Lech, M.E.
SPATIAL INFORMATION FOR THE NATION