Davenport Defines Large Potash Exploration Target from Nohra-Elende Sub-Area
(firmenpresse) - DAVENPORT DEFINES LARGE POTASH EXPLORATION TARGET FROM NOHRA-ELENDE SUB-AREA
-
Highlights
- Additional Potash tonnage defined as an Exploration Target from the Nohra-Elende sub-area, part of the Mühlhausen-Nohra Mining Licence.
- New Exploration Target contains between 66 and 117 million tonnes of K2O from the Upper Sylvinite and Lower Carnallitite seams.
- Sylvinite seam Exploration Target of 179 to 223 million tonnes grading between 11.0% and 13.5% K2O, and containing between 22 and 27 million tonnes of K2O.
- Carnallitite seam Exploration Target of between 459 and 939 million tonnes grading at between 8.5% and 10.5% K2O. Contains between 44 and 89 million tonnes of K2O, with an average seam thickness of 26m.
- Exploration Target area bordered by Davenport-controlled JORC Inferred resources both to the north and to the south.
Next Steps
- Targeted programme to upgrade JORC Inferred Resources to Measured and Indicated Resources via confirmation drilling in selected areas.
- Once Inferred Resources are upgraded to Measured and Indicated category, Davenport will conduct an economic study, scheduled for completion by the end of 2019.
Davenport Managing Director Dr Chris Gilchrist said:
The results of the Exploration Target confirm the sheer scale of the potential potash resources located throughout the entire Mühlhausen-Nohra Mining Licence. The results of the mineral resource estimates for Mühlhausen-Keula and Nohra-Elende, released on 16th October 2018 and 13th November 2018 respectively, identified a combined total JORC Inferred mineral resource of 2,822 Mt at a grade of 10.2% K2O. Based on the quality and quantity of the historical data used to create the geological model, a portion of the Nohra-Elende sub-area was excluded as an Inferred mineral resource and was classified as an Exploration Target. With a current total of now over 3.4 billion tonnes of JORC Inferred Resources, and an additional 638 to 1,162 million tonnes of additional Exploration Target under our control, we are one step closer to declaring Europes largest potash resource. Further review work of historical data from our Küllstedt licence is ongoing and permitting to drill in 2019 has made satisfactory progress and is now at an advanced stage. Once confirmatory drilling and economic studies have been completed, we will regard 2019 as a pivotal year for Davenport.
Davenport Resources (ASX: DAV) (Davenport, the Company) is pleased to announce the estimation of an Exploration Target on its Nohra-Elende sub-area of between 638 and 1,162 million metric tonnes at a potash grade between 9.2% and 11.07% K2O. The Exploration Target, covering an area of approximately 13.9 km2 (Figure 1), contains between 66 and 117 million tonnes of K2O and lies between two areas of Inferred Potash Resources, both held by Davenport, Figure 2.
Note: The potential quantity and grade of the Exploration Target is conceptual in nature. There has been insufficient exploration to estimate a mineral resource and it is uncertain if further exploration will result in the estimation of a mineral resource.
https://www.irw-press.at/prcom/images/messages/2019/45638/Nohra-Elende Exploration Target Release 15 Jan 2019 - DRAFT v1.2_PRCOM.001.jpeg
Figure 1: Exploration Target area covering approximately 13.9 km2 located within the Mühlhausen-Nohra mining licence, which is in itself comprised of two sub-areas as follows: (a) Mühlhausen-Keula (Green) to the south and (b) Nohra-Elende (Red) to the north. This announcement refers solely to the JORC Exploration Target contained within the northern Nohra-Elende sub-area (Red, Hatched).
The Nohra-Elende sub-area, which contains the Exploration Target area, has been extensively explored for potash since the late 1800s. Under former GDR state control, the largest and most detailed phase of exploration was carried out during the 1960s and 1970s. An extensive database from a total of 28 drill holes from within the Nohra-Elende sub-area and 64 drill holes from outside the area were used to support the geological and resource modelling work carried out by Micon International Ltd (Micon). The results of the modelling exercises resulted in a combined total JORC Inferred mineral resource of 2,822.2 Mt at a grade of 10.24% K2O for Nohra-Elende (ASX release 13th Nov 2018) and Mühlhausen-Keula (ASX release 16th October 2018). During the Nohra-Elende modelling, a portion of the sub-area was excluded as an Inferred mineral resource and was classified as an Exploration Target. This announcement includes the results of the Nohra-Elende Exploration Target only.
The results of the Exploration Target modelling work compare well with the historic resource estimates and exploration target values defined by German consultants ERCOSPLAN in 2018 (DAV announcement 10th April 2018). The Ercosplan Exploration Target grade estimate is comparable to the 6th November 2018 Micon Inferred mineral resource estimate. However, the Micon Inferred mineral resource tonnage is approximately 15% less than the Ercosplan Exploration Target tonnage estimate. This was due to the fact that Micon chose to leave some of the Nohra-Elende sub-area as an Exploration Target as there was not sufficient information to convert it all to an Inferred mineral resource. The Exploration Target reported by Micon is the focus of this announcement.
Mühlhausen-Nohra is one of three perpetual mining licences in the South Harz Basin that Davenport acquired in 2018 from German government agency Bodenverwertungs-und-verwaltungs GmbH (BVVG), (Figure 2). Davenports JORC compliant Inferred Resources lie adjacent to the Küllstedt Exploration Licence (Figure 2).
https://www.irw-press.at/prcom/images/messages/2019/45638/Nohra-Elende Exploration Target Release 15 Jan 2019 - DRAFT v1.2_PRCOM.002.jpeg
Figure 2: Location of Mühlhausen-Nohra mining license area showing adjoining mining license areas Ebeleben and Ohmgebirge. Davenport also has exploration licenses and historical drill data for the massive Küllstedt and Gräfentonna areas. The JORC Inferred Resource of 1.7 Bt for Nohra-Elende is contained within the red hatched areas shown above
The drill hole database considered for the Nohra-Elende sub-area consists of 92 drill holes made up of 4 hydrocarbon exploration drill holes and 88 diamond core potash exploration drill holes. Not all the drill holes considered for modelling of the JORC Inferred resource and Exploration Target are located exclusively within the licence area. A total of 64 of the 92 Project drill holes are located outside and adjacent to the licence boundary (Figure 1), but sufficiently close such that they have been deemed to have a material impact on the geological modelling and mineral resource estimation process.
All samples for the JORC Inferred resource and Exploration Target estimate were taken during historical drilling campaigns carried out predominantly during the 1960's and 1970's with eight holes drilled in the 1980s and an additional 20 drill holes drilled between 1890-1909 most of which were stopped before intersecting the potash horizon. Sample data exists from three hydrocarbon drill holes that were geophysically-logged and 35 diamond core drill holes ('potash drill holes') that produced core samples.
All drill hole sampling was conducted according to the procedures and protocols as specified in Kali-Instruktion (1956 and 1960). Drill core samples were collected from all of the potash drill holes. Where possible, the K2O grade of the potash-bearing horizons was historically determined on an empirical base using the correlation with the downhole natural gamma log. Samples were collected across all potash-bearing horizons and the total sampled length represents the total thickness of the potash-bearing horizon of the z2KSt. In the potash drill holes, core sample thicknesses ranged from 0.18 m to 4.00 m. Over inhomogeneous potash horizons where interlayers of potential waste were included, the minimum sample thickness was 0.5 m and the maximum was 5 m. Samples were crushed to 2 mm in a jaw crusher and a representative sample was milled and crushed further to 50 m. This sub-sample was assayed by ICP-OES for all elements except NaCl, which was analysed using potentiometric titration. XRD was used for mineralogy and thin sections were carried out at a local university.
Geology and modelling
The geological model and mineral resource estimation for the Nohra-Elende sub-area was conducted in Micromine®, a software package used for geologically modelling stratiform deposits. The database used to create the geological model and mineral resource estimate was created from the manual data entry of hard copy historical drill hole logs and exploration records.
The drill hole database was imported into Micromine® and validated. Validation checks undertaken included checking for missing samples, mismatching sample and stratigraphy intersections, duplicate records and overlapping from-to depths. No mistakes in the database were identified. Once imported into Micromine®, geological interpretation was carried out in 2-D cross-sections and 3-D downhole plots of lithology and grade. This process confirmed the correlating relationship between the drill hole logs and the geophysical logging as well as the stratigraphic-hosted nature of the potash mineralisation. Micon also noted that in some instances the mineralisation zone containing grade goes above the z2KSt seam into the overlying Dechsteinsalz (zZNAr) as a result of alteration from ascending brines e.g. Kal Ele 19/1978.
The chemical database was first composited according to stratigraphy, which allowed the merging of the mineralogical and chemical data tables. The composited database was assigned a tag column to indicate if a sample was sylvinite or carnallite based on the mineralogical drill hole logging data and the chemical assay data.
Some drill holes did not have a full suite of chemical data, for example, a number of drill holes did not have assay results for MgSO4. In these instances, a length weighted average dummy value was assigned. Some drill holes had missing sample intervals such as Kal Ele 12/1977 which has 12 cm of unsampled material in between samples 29 and 30. In instances such as this Micon checked the stratigraphy file for any comments regarding core loss and ensured that the sequence was logged as the z2KSt. If the missing sample was less than 30cm a dummy sample value was inserted based on the results for the samples above and below the missing one.
The Nohra-Elende database contains some drill holes with duplicated stratigraphy indicating faulting or folding. These were numbered according to elevation and cross-sections drawn to determine which portion of the z2KSt would be used for modelling.
Each drill hole was individually examined and, based on stratigraphy, sequence of mineralised seams and K2O composite grades, the Sylvinite or Carnallitite seams were further divided into the Upper Sylvinite seam, Carnallitite seam and Lower Sylvinite seam. Only the Upper Sylvinite and Carnallite seams occur within the Exploration Target area. Micon created histograms of the K2O grade and thickness for each seam. The Carnallitite seam displays continuous grade but the thickness is more variable ranging from 0.5m to 63m and displays faulting. The Sylvinite seams have relatively consistent grade and thickness. No top cut was applied to any of the seam grades. Within the Exploration Target area itself the z2KSt stratigraphic sequence was only intersected in Kal NSo 8/1907, which contained 9.12 m of Upper Sylvinite at a grade of 12.26% K2O and 26.60 m of Carnallite at a grade of 9.52% K2O. The thickness of the Upper Sylvinite is considerably higher than in other drill holes on Nohra-Elende and this should be investigated in the future will infill drilling in the area.
The database was composited again, this time by grade, using a minimum trigger of 5% K2O, a minimum grade length of 0.5 m, a maximum total length of waste of 2 m and a 1 m maximum consecutive length of waste.
Roof and floor grids were made for each of the four seams. The minimum and maximum X and Y origins used for gridding were 601233 (min X), 5690017 (min Y), 622433 (max X) and 5706817 (max Y). A grid cell size of 400 was used as this best fitted the data when correlated in cross-section. An inverse distance squared gridding algorithm was used, with a circular search area and a 5,000 m search radius to cover the distance between data points, one sector and maximum 1 point per sector. The roof and floor grids were converted to wireframe surfaces (DTM).
In addition, Micon was provided with data for drill holes located in adjacent areas flanking the Project area of the Mühlhausen-Nohra mining licence. The surfaces were cut according to the limits of the seams that extend outward of the Mühlhausen-Nohra mining licence boundary. The surfaces were additionally cut to the licence boundaries forming a second set of DTM surfaces for analysis. Lastly, two sets of solid wireframes were created for the Upper Sylvinite seam, Carnallitite seam and Lower Sylvinite seam using the roof and floor surfaces. The first set of wireframes represents the total extent of potash mineralisation based on the complete set of data provided, while the second set of wireframes represents the potash seam mineralisation cropped by the Project licence boundary. A cross section of the resultant solid wireframes is shown in Figure 3 of JORC Table 1.
The final extents of the modelled Upper Sylvinite seam, Carnallitite seam and Lower Sylvinite seam is shown in Figure 4 in JORC Table 1. Faulting has not been identified within the Exploration Target area but does occur within the Nohra-Elende sub-area so the possibility of discovering faulting cannot be ruled out.
Exploration Target
Based on the extended wireframing across the whole of the Nohra-Elende sub-area and the mineralised intersection recorded in drill hole Kal NSo 8/1907, the potash deposit appears to extend across the whole of the Exploration Target area Figure 4 of JORC Table 1.
The mineral resources have been restricted by a total seam thickness (>1 m), grade (>5% K2O) and the licence area boundary.
The average thicknesses of the wireframes are:
- Upper Sylvinite seam is 1.78 m;
- Carnallitite seam is 26.06 m; and
- Lower Sylvinite seam is 1.99 m.
The minimum depth from surface to the roof of the uppermost seam, the Upper Sylvinite seam, is ±692 m towards the north of the Exploration Target area increasing towards the south to a depth of ±815 m. The modelled seam package is sub-horizontal with localised gentle undulations.
A grade-tonnage report was generated for the three seams using average densities obtained from historical records, specifically: 2.17 t/m³ for Upper Sylvinite seam, 1.90 t/m³ for the Carnallitite seam and 2.30 t/m³ for the Lower Sylvinite seam. The grades for each wireframe have been reported based on the modelled composited assay database, which were modelled using the same algorithm and parameters as the seam roof and floor surfaces. The modelled K2O grade and width of the composited potash seams and the depth of the Upper Sylvinite seam roof are indicated in Figures 5 to 7 in JORC Table 1.
The portion of the Nohra-Elende sub-area discussed in this announcement has been classified as an Exploration Target following the guidelines defined in the 2012 edition of the JORC Code. The estimated grade and tonnage ranges were defined using the criteria shown in Table 1.
Table 1: Criteria used to define the Exploration Target ranges
Category Criteria
Minimum An area approximately 1,500m
tonnage surrounding
Kal NSo 8/1907 taking into
consideration the
surrounding drill holes
with
information.
Maximum The entire area joining the
tonnage two Inferred resource areas
to the north and south of
Nohra-Elende.
Minimum The K2O grade from drill
grade hole
Kal NSo 8/1907 discounted by
10%
Maximum The K2O grade from drill
grade hole
Kal NSo 8/1907 credited by
10%
The spacing between drill holes ranges from ±400 m to ±2,800 m. Figure 5 in JORC Table 1 highlights the extents of the Exploration Target.
The Exploration Target for the Nohra-Elende sub-area in accordance with the Micon report of 8th January 2019 is presented in Table 2.
Table 2: Exploration Target Estimate for the Nohra-Elende Sub-Area of the Mühlhausen-Nohra Mining Licence as at 8th January 2019 (in accordance with the guidelines of the JORC Code (2012)
Seam JORC Tonnage (Mt) K2O (%) K2O (Mt)
Categor
y
MinimumMaximumMinimumMaximumMinimumMaximum
Upper SExplora179 223 11.0 13.5 22 27
ylvinittion
e Target
CarnallExplora179 223 11.0 13.5 22 27
itite tion
Target
Total NExplora638 1,162 9.20 11.07 66 117
ohra-Eltion
ende Target
Sub-Ar
ea
Notes:
1. Mineral resources presented according to ore type (mineralogy) and not as per stratigraphy.
2. Minimum seam thickness considered for resources is 1 m.
3. Minimum cut-off grade 5% K2O.
4. 20% geological loss applied to account for potential unknown geological losses for Inferred resources.
5. Data source: historical state records (BVVG) checked and verified.
6. Inferred resources rounded down to nearest 100,000 t.
7. Errors may exist due to rounding.
The total JORC-compliant Inferred Resources declared by Micon as a result of modelling the drill hole data from Ebeleben, the Mühlhausen-Keula and the Nohra-Elende areas are shown in Table 3 below. Total resources held under the JORC 2012 Inferred category now stand at approximately 3.4 billion tonnes containing 358.8 Mt K2O. Davenport anticipates that this number will increase further during 2019 with the completion of modelling work on the Küllstedt Exploration licence, and through exploration of the remaining licence areas.
Table 3: Total JORC 2012 Inferred Resources to November 2018 held by Davenport.
Seam Tonnage K2O K2O
(Mt) (%) (Mt)
Sylvinite 324.0 15.6 50.4
Carnallitite 252.6 7.5 18.9
Total Ebeleben 576.6 12.1 69.3
Sylvinite 834.3 12.1 100.7
Carnallitite 295.8 8.2 24.2
Total Mühlhausen-Keula 1,130.1 11.1 124.9
Sylvinite 101 14.19 14
Carnallitite 1,597 9.41 150
Total Nohra-Elende 1,698 9.69 165
Total Davenport JORC Inferred 3,404.7 10.5 358.8
Resources to
Date
Ongoing & Future Work
Work is ongoing to review the historic drill hole data and technical reports from the Küllstedt Exploration Licence area with an aim to convert historic resources to JORC 2012 compliant resources. This work is scheduled for completion in the coming weeks.
The next steps for Davenport are to upgrade JORC Inferred Resources to JORC Indicated Resources by carrying out confirmation and exploration drilling in selected target areas during early 2019. Davenport expects the number of drill holes required for this purpose will be two. Progress is being made with local authorities and landowners to obtain permission to drill and offers from drilling contractors are being reviewed. Davenport expects to release an update on the preparations for drilling in the near future.
INVESTOR & MEDIA ENQUIRIES
Dr Chris Gilchrist - Managing Director
Davenport Resources Ltd
+353 41 988 3409
+353 87 687 9886
cgilchrist(at)davenportresources.com.au
David Tasker - Managing Director
Chapter One Advisors
+61 433 112 936
dtasker(at)chapteroneadvisors.com.au
Paul Cahill - Managing Director
Bacchus Capital Advisers Ltd
+ 44 (0) 203 848 1643
paul.cahill(at)bacchuscapital.co.uk
COMPANY DETAILS
Davenport Resources Limited
ABN: 64 153 414 852
ASX CODE: DAV
ASX CODE (Options): DAVO
FRANKFURT CODE: A2DWXX
PRINCIPAL AND
REGISTERED OFFICE
(& Postal Address)
Davenport Resources Limited
Level 1,
675 Murray Street,
West Perth WA 6005
PO Box 1088
West Perth WA 6872
W: www.davenportresources.com.au
E: info(at)davenportresources.com.au
P: +61 (08) 9481 0389
Capital Structure
143.1M Ordinary shares
16.6M Unlisted options
6.2M Performance Rights
34.4M Listed Options
BOARD OF DIRECTORS
Patrick McManus
(Non-Executive Chairman)
Dr Chris Gilchrist
(Managing Director)
Rory Luff
(Non-Executive Director)
Dr Reinout Koopmans
(Non-Executive Director)
Competent Person Statement
Elizabeth de Klerk M.Sc., Pr.Sci.Nat., SAIMM., Micons Senior Geologist and Competent Person visited the South Harz Potash project from 12th to 16th February 2018 and 6th to 8th March 2018. During the initial site visit, the historical drilling area and laboratory facilities at K-Utec Salt Technologies Ltd in Sondershausen were visited. The original drill hole logs, reports, maps and cross-sections held in the Bodenverwertungs and verwaltungs GmbH (BVVG) archives in Berlin were also inspected. In addition, Mrs. de Klerk interviewed the Ercosplan team at their offices in Erfurt to understand how the data were used to compile an Excel database and generate an initial Exploration Target for Mühlhausen-Nohra. The second site visit involved more time spent at K-Utec inspecting additional historical records for Mühlhausen-Nohra held in the archives at the offices of K-Utec Salt Technologies Ltd in Sondershausen.
Please find the whole press release under the following link:https://www.asx.com.au/asxpdf/20190115/pdf/441w3tqyx185h0.pdf
Leseranfragen:
Datum: 15.01.2019 - 12:15 Uhr
Sprache: Deutsch
News-ID 586282
Anzahl Zeichen: 23590
contact information:
Town:
Wien
Kategorie:
Business News
Diese Pressemitteilung wurde bisher 185 mal aufgerufen.
Die Pressemitteilung mit dem Titel:
"Davenport Defines Large Potash Exploration Target from Nohra-Elende Sub-Area
"
steht unter der journalistisch-redaktionellen Verantwortung von
Davenport Resources (Nachricht senden)
Beachten Sie bitte die weiteren Informationen zum Haftungsauschluß (gemäß TMG - TeleMedianGesetz) und dem Datenschutz (gemäß der DSGVO).
