{
 "schema": "ausmt-survey-metadata",
 "version": "0.1",
 "survey_id": "black-hill-2005-06",
 "title": "Black Hill 2005-06",
 "dates": {
  "coverage": {
   "year_start": 2005,
   "year_end": 2006
  }
 },
 "abstract": "A broadband magnetotelluric survey over the Black Hill area of South Australia, on a footprint\nrunning from 67 to 157 km north east of Adelaide with its centroid about 100 km out, acquired by\nQuantec Consulting Inc. for Inco Resources (Australia) Pty Ltd as project QCL-414 in two\ncampaigns, 19 October to 14 December 2005 and 17 January to 15 February 2006. The target was\nmagmatic nickel, copper and platinum group element mineralisation in the Black Hill Complex, a\nsulphide saturated mafic body considered prospective for Voisey's Bay style deposits, lying along\na cross fault that cuts the structural corridor between the Adelaide Fold Belt and the Kanmantoo\nFold Belt. Magnetotellurics was chosen because Murray Basin cover is thick and conductive enough\nthat an earlier airborne electromagnetic survey was judged effective over only about a third of\nthe area.\nSoundings were remote referenced tensor measurements on an L shaped array with 100 m electric\ndipoles and three induction coils per site, drawn from a fleet of six EMI coils of models BF-4,\nBF-7 and BF-21, recorded on Quantec RT-130 loggers at 1000 samples per second for 2 to 14 hours\nper site. The report's text describes the dipoles as Ex east and Ey north, but the delivered\nchannel geometry says otherwise in all 229 delivered files: Ex runs east and Ey runs south, with\nthe magnetic pair at 90 and 180 degrees. That layout is what makes the acquisition frame a clean\nquarter turn from the standard one, and it is the geometry the rotation below relies on. Two\nloggers ran simultaneously for the site and its remote reference, synchronised by GPS. Station\nspacing was a nominal 500 m with infill to 250 m on some lines. Processing was full waveform time\nseries to the frequency domain with QGL QuickLay 2.25.28, and the transfer functions were exported\nby Geotools 2.3.\nThis package covers all 17 lines the survey ran: 409 transfer functions over 406 distinct sites\nplus three repeat occupations on line 8, on 22 to 63 periods with a median of 35, spanning roughly\n351 seconds to 239 Hz. It is assembled from two sources of very different standing, and every\nstation declares in its own file which of the two it is, under the key\nausmt.station.tf_provenance.\n229 stations on lines 2, 4, 8, 10, 19, 20, 21, 22, 23, 24, 27 and 28 are contractor-processed.\nThey are served as a derived rendition of the custodian's delivery, which is cross-spectra stored\nin an acquisition frame with the electric x axis east, declared by ROTSPEC 90 and by sensor\nazimuths of 90 and 180. What is served is the impedance tensor computed from those spectra and\nrotated into the standard magnetotelluric frame, x north and y east, by the transformation\nZ_std = R Z R transpose with theta the negative of the declared frame. Each file states its source\nfile and that file's sha256, the rotation applied, and the convention by which the variances were\ncarried through. These files carry a complete tensor: diagonal and off diagonal impedance with\nvariances, and tipper with variances, at every frequency.\n180 stations on lines 11, 12, 16, 25 and 26 are figure-recovered. The custodian never delivered\nthem as data and no transfer function for them survives in any SARIG system; their only surviving\nform is the sounding curve figures in the contractor's reports, 52 of them in the report delivered\nwith the data and 128 in the EL 3122 annual technical report. Those figures were read from the\nreports' own vector drawing operators, with no raster image and no character recognition, and\nrebuilt as transfer functions. The method was scored first against the 219 stations that appear\nboth as a figure and as a delivered file, and agrees with them to a median of 0.0010 of a decade\nin apparent resistivity and 0.05 of a degree in phase, with no systematic sign to the disagreement\nin either. These 180 stations carry the off diagonal impedance and the tipper only: the report\nfigures plot no Zxx and no Zyy, so they have no diagonal impedance, no phase tensor and no\ndimensionality call, and none has been inferred. Their uncertainty is the contractor's stated\nsurvey wide data accuracy rather than a per station measurement, and they carry no tipper\nuncertainty because the figures draw none. Every absent value in those files is written as the\nliteral nan, because the format's own EMPTY marker is read back as a measured zero by the common\nreader of this format; nan is not a token the SEG EDI standard defines, and a strict third party\nreader may reject it or mishandle it. No value in the 229 contractor-processed files is nan.\nData origin. The 229 contractor-processed transfer functions are SARIG's delivery for electrical\nsurvey 22, BLACK HILL, 229 sites on tenements EL 3304 and EL 3305. Two identifiers are needed\ntogether. The dataset record Magnetotelluric and geomagnetic depth sounding surveys,\nhttps://pid.sarig.sa.gov.au/dataset/mesac1113, is what magnetotelluric transfer functions are\npublished under statewide and is the licence of record; all 229 of those stations sit in its\nelectrical survey layer, but it names no downloadable resource for this survey, because SARIG\ngenerates this delivery on demand rather than attaching it. The survey itself is documented in\nSouth Australian open file company report envelope 11269,\nhttps://pid.sarig.sa.gov.au/document/mesac21595, and the contractor's logistics report is\ndelivered with the data. The 180 figure-recovered transfer functions come from Appendix B,\nSounding Curves, of that same logistics report for line 11, and from Appendix B of the logistics\nreport bound inside EL 3122 open file envelope 11133,\nhttps://pid.sarig.sa.gov.au/document/mesac25554, for lines 12, 16, 25 and 26. Release is open file\nby the Geological Survey of South Australia.",
 "subjects": [
  {
   "code": "370602",
   "scheme": "ANZSRC-FoR-2020",
   "label": "Electrical and electromagnetic methods in geophysics",
   "uri": "https://linked.data.gov.au/def/anzsrc-for/2020/370602"
  }
 ],
 "creators": [
  {
   "name": "Crabb, T.N.",
   "name_type": "person"
  },
  {
   "name": "Mortimer, L.",
   "name_type": "person"
  },
  {
   "name": "Doerner, W.",
   "name_type": "person"
  },
  {
   "name": "Maude, G.",
   "name_type": "person"
  }
 ],
 "contributors": [
  {
   "name": "Doerner, W.",
   "name_type": "person",
   "role": "ProjectLeader"
  },
  {
   "name": "Quantec Consulting Inc.",
   "name_type": "organisation",
   "role": "DataCollector"
  },
  {
   "name": "Scappin, S.",
   "name_type": "person",
   "role": "DataCurator"
  },
  {
   "name": "Milne, J.",
   "name_type": "person",
   "role": "DataCurator"
  },
  {
   "name": "Inco Resources (Australia) Pty Ltd",
   "name_type": "organisation",
   "role": "Sponsor"
  },
  {
   "name": "Geological Survey of South Australia",
   "name_type": "organisation",
   "role": "Distributor"
  }
 ],
 "organisations": [
  {
   "name": "Geological Survey of South Australia",
   "roles": [
    "custodian",
    "publisher",
    "distributor"
   ],
   "primary_custodian": true
  },
  {
   "name": "Quantec Consulting Inc.",
   "roles": [
    "data_collector"
   ]
  },
  {
   "name": "Inco Resources (Australia) Pty Ltd",
   "roles": [
    "rights_holder"
   ]
  }
 ],
 "rights": {
  "license": "CC-BY-4.0",
  "access": "open"
 },
 "extent": {
  "bbox": {
   "west": 139.167822,
   "south": -34.670092,
   "east": 139.591656,
   "north": -33.740147
  }
 },
 "relationships": [
  {
   "identifier": "https://pid.sarig.sa.gov.au/dataset/mesac1113",
   "identifier_type": "URL",
   "relation": "IsVariantFormOf"
  },
  {
   "identifier": "https://pid.sarig.sa.gov.au/document/mesac21595",
   "identifier_type": "URL",
   "relation": "IsDerivedFrom"
  },
  {
   "identifier": "https://pid.sarig.sa.gov.au/document/mesac25554",
   "identifier_type": "URL",
   "relation": "IsDerivedFrom"
  }
 ],
 "attribution": {
  "custodian": "Geological Survey of South Australia",
  "changes_made": true,
  "changes_summary": "This release is a derived rendition in two classes, and every one of its 409 files declares which class it is under ausmt.station.tf_provenance. For the 229 contractor-processed stations: impedance tensors computed from the delivered cross-spectra and rotated from the acquisition frame into the standard magnetotelluric frame; stations named from the contractor's own SECTID; two defective coordinates repaired against the contractor's coverage tables. For the 180 figure-recovered stations: the custodian delivered no data at all, and the transfer functions were read from the sounding curve figures in the contractor's reports, taken from the PDF's own vector drawing operators and rebuilt as files. Those 180 carry the off diagonal impedance and the tipper only, because the figures plot no Zxx and no Zyy, so they have no diagonal impedance and no phase tensor and none is inferred; their uncertainty is the contractor's stated survey wide data accuracy rather than a per station measurement, and they carry no tipper uncertainty because the figures draw none. Every absent value in those files, the diagonal and the tipper uncertainty included, is written as the literal nan rather than as the format's EMPTY sentinel, which the common reader of this format turns into a measured zero; nan is not a token SEG EDI defines and a strict third party reader may object to it. Both classes are served in one frame, under one survey, with one station naming scheme.",
  "declared_by": "Ben",
  "declared_date": "2026-09-11"
 },
 "provenance": {
  "generated": "2026-09-12T00:17:51Z",
  "generator": "ausmt/extract.build_portal 0.2.1"
 }
}