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REDROCK PROPERTY CSAMT SURVEY - III GIS COMPILATION

CSAMT Lines Phases I, II and III

James L. Wright M.Sc. December 18, 2011

TABLE OF CONTENTS

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . 2 SURVEY PROCEDURE . . . . . . . . . . . . . . . . . . . . . . 3 DATA PROCESSING . . . . . . . . . . . . . . . . . . . . . . . 4 INTERPRETATION . . . . . . . . . . . . . . . . . . . . . . . 6 CONCLUSIONS AND RECOMMENDATIONS . . . . . . . . . . . . 13 REFERENCES APPENDIX A- CSAMT LOGISTICS APPENDIX B- PROPOSED DRILL HOLES & RESISTIVITY SECTIONS DVD HOLDER- DATABASE DVD MAP BINDER (1:6000 & 1:12000 Sets) -

CSAMT SURVEY, LINES GRAVITY RESIDUAL, CSAMT STRUCTURES - III

GRAVITY RESIDUAL, GRAVITY STRUCTURES - III CSAMT SURVEY, LINE 4457930N, INVERTED RESISTIVITY SECTION/ GRAVITY CSAMT SURVEY, LINE 4458130N, INVERTED RESISTIVITY SECTION / GRAVITY CSAMT SURVEY, LINE 4458330N, INVERTED RESISTIVITY SECTION / GRAVITY CSAMT SURVEY, LINE 4458530N, INVERTED RESISTIVITY SECTION / GRAVITY CSAMT SURVEY, LINE 4457930N, INVERTED RESISTIVITY SECTION / GEOLOGY CSAMT SURVEY, LINE 4458130N, INVERTED RESISTIVITY SECTION / GEOLOGY CSAMT SURVEY, LINE 4458330N, INVERTED RESISTIVITY SECTION / GEOLOGY CSAMT SURVEY, LINE 4458530N, INVERTED RESISTIVITY SECTION / GEOLOGY

J L WRIGHT GEOPHYSICS 1

INTRODUCTION A third controlled source audio magneto-telluric (CSAMT) survey was completed over a portion of the REDROCK property with the objective of defining structures and lithologies associated with gold mineralization. Gravity in conjunction with the earlier CSAMT work, reported upon by Wright (2010, 2011a, 2011b), demonstrated the effectiveness of CSAMT for structural / lithologic mapping on the property. Indeed, an initial gravity survey with CSAMT follow-up is a standard technique applied with success in Nevada. Figure 1 shows the property outline relative to roads, county boundaries and topography.

FIGURE 1: Property Location Results of the survey are provided in digital and map formats. Digital products included all raw data and processed files, as well as MAPINFO and ARCGIS GIS files for the four (4) inverted resistivity sections. Also included are data and GIS files for a number of related data sets such as regional gravity, topography, geology, etc. The combined files constitute a complete GIS data base for the property. Maps include inversion section plots with interpretive overlay for the four lines at both 1:6000 and 1:12000 scales over residual gravity and geology. The lines traces are also provided as plots over the topography at both scales. All plot files are also included in digital form as SURFER V10 SRF files. Files, both digital and map, are contained on a DVD located in a sleeve at the rear of the report. A README file on the DVD explains the folder / file organization. Survey procedures and data processing are first reviewed followed by an interpretation of the CSAMT survey with incorporation of multiple data sets. Finally, recommendations and conclusions are presented, along with several proposed drill holes.


SURVEY PROCEDURE Figure 2 shows a CSAMT line plot overlying topography, which includes lines from all three surveys. The lines are oriented east-west, spaced 300m and arranged to cut the northwest Caetano Break, as well as northeast and north-south structures. Line numbers correspond to the NAD 27 / UTM 11N northing. Zonge Geosciences, Inc. based in Reno, Nevada conducted the data acquisition under Zonge job number 11212. The survey was conducted during the period of Dec. 4 – 7, 2011 and covered a total of 7.4 line - km. Survey control was established by Zonge personnel using a Trimble PRO-XRS GPS receiver with real time differential corrections provided by OMNISTAR. CSAMT data were acquired using a 50 meter electric-field receiver dipole. Measurements were made in spreads consisting of four electric-field dipoles (4 Ex/1 Hy) with a magnetic-field antenna located in the center of the spread. The data were acquired in the broadside mode of operation with the electric-field dipoles oriented along the survey line and parallel to the transmitter dipole (x component). The magnetic antenna was oriented perpendicular to the survey line. Measurements were made at frequencies ranging from 0.25 Hz to 8192 Hz in binary steps. One CSAMT transmitter, of a grounded dipole configuration, was used for this survey.

FIGURE 2: CSAMT Lines (Phase I – Green / Phase II – Blue / Phase III – Red)

Data were acquired with two Zonge model GDP-32 receivers and a Zonge GGT-30 transmitter. The GGT-30 is a constant-current 30 KVA transmitter. Power for the transmitter was provided by a Zonge ZMG-30 motor-generator with a VR-1 voltage regulator. The transmitter was controlled by an XMT-32 transmitter controller. Transmitter-receiver synchronization was maintained with identical crystal oscillators, synchronized each morning before data acquisition.


Data quality was monitored in the field by the operator. Real-time standard-error values are displayed during acquisition. In addition, multiple measurements at a range of frequencies are displayed graphically as resistivity versus frequency curves with error bars showing the data scatter. This allows a visual evaluation of the data quality and remedial action to be taken if necessary. Data quality is also evaluated during post-acquisition processing by reviewing data component plots. Data are edited to remove spurious data if necessary. As a whole, the data are of good quality typified by repeated measurements generally within 5 percent. The smooth nature of the curves and lack of noticeable error bars also demonstrates good data quality. Additional logistical details are available in Appendix A, where a more complete discussion of the various aspects of the survey is presented. DATA PROCESSING Zonge Geosciences provided averaged and edit files, along with station survey information, for each line in standard Zonge AVG and STN files. These data were processed with Zonge’s SCS2D two dimensional, smooth model CSAMT inversion software version 3.20r. A variable cell size ranging from 50x35m to 50X65m was selected to better refine data fits. Prior to additional processing all inverted resistivities were converted to logarithms base ten. Gridding with a kriging algorithm using a five meter spacing was implemented. The grids were then mask to the topography, line limits and a depth extent of approximately 700m. Finally, the inverted sections were colored and contoured for map preparation. Contour interval on all plots is 0.05 log ohm-m. The resistivity color bar for all products, including GIS files, follows. The contour interval and color bar are consistent with the first two CSAMT surveys.

Complete Bouguer Anomaly (CBA) residual gravity data are included as a back-drop to the CSAMT sectional results. Wright (2010) reports on the survey and the color scale used for the plots and figures follows.


FIGURE 3: Plot Example

As noted previously, paper plots are provided at two scales along with SRF plot files. Figure 3 shows an example plot of a CSAMT section with all plots located in the accompanying binder. The inverted data for all lines from both all three surveys were merged and imported into the VOXLER 3D visualization program, an example image from the program follows.

FIGURE 4: VOXLER Inverted Sections Looking East


INTERPRETATION Figures 5 to 8 show the inverted resistivity sections for the lines rotated to plan about the line. Underlying the sections is the property scale geology of Conway et. al. (2007). Overlying the section is an interpretation with structures depicted with dashed or barbed (thrusts) lines and contacts with dotted lines. Various interpreted rock units are labeled. Possible silica alteration (Si) is denoted with a cross-hatched pattern. The silica alteration interpretations are based upon resistivity highs at locations which the geology suggests should not be highly resistive. However, several of the chert and quartzite units in the rock package exhibit similar resistivities. Thus the alteration interpretation should be considered speculative. The four lines have several common features. A wedge of Caetano Tuff and Quaternary colluvium (Tct / Qal / Qc) laps on to the west ends of all lines. Sub-horizontal layering is evident within the wedges. The Caetano Fault also occurs on all lines near the east edge of the Tct / Qc wedge or slightly to the west of outcrop within the basin. Interestingly, the fault does terminate the Paleozoic (Pz) outcrop, but a major down-drop of the Pz is not indicate, rather a series of closely spaced structures down-drops Pz to the west. The Caetano Fault is manifested in the resistivity as a near vertical, relatively conductive zone cutting the Pz basement. Such a response is consistent with a large structure which has broken a considerable volume of rock. The broken rock increases porosity leading to reduced resistivity. The “Collision Zone”, first detected in the second phase of CSAMT surveying, is also evident on all lines. However, rather than a collision, the zone is marked by forming the western termination of a deeper conductive layer. This layer dips slightly to the east on the northern most line but progressively rotates until on the southern line the dip is clearly to the west. A number of areas interpreted as silica (Si) alteration are noted on the lines; however, chert can produce similar resistivity values. Figure 9 shows the geology overlain by a plan view of the Caetano Fault and Collision Zone structures projected from the sectional interpretations. Note each of these features is composed of a number of structures, as would be expected for such large scale features. Also shown on the figure are the soil gold values in the standard proportional dot format. A color legend for the soil gold geochemistry is shown below. This legend applies to all gold soil geochemical data presented in the report.

Gold Soil Geochemistry Legend


FIGURE 5: L4458530N Inverted Resistivity Section over Geology



FIGURE 9: Major Structures, Au Soil Geochemistry over Geology Both the Caetano Fault and Collision Zone are extended by the third phase CSAMT survey. Agreement with the mapped geology is quite good for the Caetano Fault. However, the extensions to the Collision Zone still have no obvious correlation in the mapped geology. Interestingly, structures within the Collision Zone tend to bound a ban of chert / argillite (DOuc) in the Devonian – Ordovician rock package. This lithologic correlation does add some geologic support to the high angle structural nature of the zone. Furthermore, as noted by Wright (2011b), slightly anomalous gold soil values do extend along the zone. A very similar situation is noted to the west in the Centerra land rectangle, where anomalous gold soil values correlate directly with mapped structures, which parallel to the Collision Zone. The Collision Zone merges with the Caetano Fault on the southern line making distinction between the two impossible. Figure 10 shows the two main structural features over the residual gravity discussed by Wright (2010). Placement of the Caetano Fault based on the CSAMT agrees perfectly with the gravity. Correlation of gravity responses with the Collision Zone is tentative at best. Clearly, the zone does not juxtapose rocks with significant density differences. However, at other locations on the gravity survey north-south contrasts can be observed, suggesting this to be an orientation of structural significance. Indeed, on a larger scale north-south structures control the entire Reese River Valley, as well as known mineralization to the north on the Overlook property. Wright (2010) presents several images showing the property scale north-south structures with obvious extensions to mineralization known in the southern Battle Mountains (i.e. Pediment and Copper Canyon).


FIGURE 10: Major Structures, Au Soil Geochemistry over Residual Gravity The agreement between the CSAMT and gravity surveys is excellent and detailed in Figures 11 to 14 where the inverted resistivity sections are shown over the residual gravity. The wedge of Tct / Qal / Qc on the west ends of the sections correlates with a gravity low. Of course, the Caetano Fault correlates directly with a steep gravity gradient along the Paleozoic Tertiary contact. On three of the four sections, silica (Si) alteration is interpreted proximal to the Caetano Fault. The alteration exhibits a high angle elongation parallel to the Caetano Fault structures and is confined to the areas immediately adjacent to the fault. Several of the interpreted Si bodies fall beneath thin Tertiary cover to the west of the main fault. No Si alteration is interpreted along the eastern ends of the lines due to mapped chert in the area. In fact, extensive high resistivity anomalies on the line’s eastern ends are identified as chert (i.e. DOuc).

The intersection of the Collision Zone with the Caetano Fault results in an apparent right lateral offset of the Caetano Fault on the order of 400m (see Figure 14). A similar apparent right lateral shift of the Caetano Fault also occurs where the north-south structure in the Centerra land package intersect the fault. Once merged the distinction between the two features is lost with the Caetano Fault persisting to the southeast for a considerable distance. Lack of gravity coverage to the south precludes determination if the Collision Zone extends into the Caetano Trough. Certainly, the Collision Zone is a significant structure with associated anomalous gold geochemistry. Interestingly, another such north-south zone appears to lie further to the east of the Collision Zone, as is evident in the gravity (see Figure 10).


FIGURE 11: L4458530N Inverted Resistivity Section over Residual Gravity



CONCLUSIONS AND RECOMMENDATIONS The phase three CSAMT survey extends detailed coverage of both the Caetano Fault 1300m and Collision Zone700m to the southeast and south respectively. Character of the Caetano Fault remains unchanged – a high angle structure with multiple stands offsetting Paleozoic rocks against Tertiary rock of the Caetano Trough. However, the Collision Zone changes character from a dramatic juxtaposition of rock units to a high angle structure with no indication of overriding rock units. In addition, rocks east of the zone change dip from east to west going from north to south.

FIGURE 15: Proposed Drill Holes, Au Soil Geochemistry over Geology

HOLE UTM_E UTM_N INCL. TD (m) P4 499975 4458530 90 530 P5 500090 4458130 90 650

TABLE 1: Proposed Hole Details

Two holes are proposed to test the southern extents of the Collision Zone. These are shown in Figure 15 over the geology as holes P4 and P5, along with the proposed holes from phase two (i.e. P1 – P3). Location and geometric details are listed in Table 1 with collar coordinates in NAD 27 / UTM 11N. Appendix B shows the holes in section. Numbering extends the earlier convention from the second CSAMT survey to avoid confusion. Rational for hole placement is also consistent with the earlier proposal – east of the Collision Zone to test proximal lower plate rocks. Leakage of mineralization along favorable bedding control is the specific target.


REFERENCES

Conway, K., Jones, W., Leger, A., Percival, T., Park, D and Dilles, P., 2007, 2007 Redrock Canyon Annual Report, Centerra (U.S.) Inc., Geologic map of the Redrock Canyon Property: Centerra (U.S.) Inc. company map. Wright, J. L., 2010, Redrock property, Gravity survey, GIS database: Challenger Deep Capital Corp. company report. Wright, J. L., 2011a, Redrock property, CSAMT survey, GIS database: Sagebrush Gold company report. Wright, J. L., 2011b, Redrock property, CSAMT - II survey, GIS database: Arttor Gold company report.


APPENDIX A

CSAMT SURVEY

ON THE

REDROCK PROJECT

LANDER COUNTY, NEVADA

FOR

ARTTOR GOLD

DATA ACQUISITION REPORT

ZONGE JOB# 11212

ISSUE DATE: 17 December 2011

ZONGE GEOSCIENCES INC.

924 Greg Street

Sparks, Nevada 89431

INTRODUCTION Zonge Geosciences, Inc. performed a controlled-source, audio-frequency, magnetotelluric (CSAMT) survey on the Redrock Project, located in Lander County, Nevada for Arttor Gold This survey was conducted during the period of 04 December 2011 to 07 December 2011. The survey area is located in Township 28 North and Range 44 East, and lies within the Redrock Spring, Nevada 7.5-minute series topographic sheet. CSAMT data were acquired on four lines for a total of 7.4 line-kilometers of data coverage. The survey was supervised in the field by Mark Ziminsky, geophysicist, and Grady Pearce, geophysicist, for Zonge Geosciences, Inc. under Zonge job number 11212. Data files were provided to client representative, James L. Wright of Wright Geophysics, for quality control, modeling and interpretation. This report covers data acquisition, instrumentation and processing. DATA ACQUISITION Zonge personnel established survey control for this project using a Trimble PRO-XRS GPS receiver. The GPS data were differentially corrected in real-time using WAAS corrections. This system provides sub-meter accuracy under standard operating conditions. Line control in the field utilized UTM Zone 11N NAD27 (CONUS) datum. CSAMT data were acquired using a 50-meter electric-field receiver dipole. Measurements were made in spreads consisting of four electric-field dipoles (4 Ex/1 Hy) with a magnetic-field antenna located in the center of the spread. The data were acquired in the broadside mode of operation with the electric-field dipoles oriented along the survey line and parallel to the transmitter dipole (x component). The magnetic antenna was oriented perpendicular to the survey line (y component). Measurements were made at frequencies ranging from 0.250 Hz to 8192 Hz in binary steps. One CSAMT transmitter, of a grounded dipole configuration, was used for this survey. The transmitter location is shown on Table 1 with coordinates in UTM Zone 11N NAD27 (CONUS), meters. Each current electrode site consisted of two pits lined with aluminum foil and soaked with salt water. The electrodes were connected to the transmitter with two lengths of insulated 14-gauge wire, separated by approximately two meters.

Table 1: CSAMT transmitter and associated survey lines

Transmitter # PID

NAD27 UTM East

NAD27 UTMNorth Length Bearing Lines

1 west 494200 4468730

1 center 494900 4468730

1 east 495600 4468730 1400 N90°E All

CSAMT MEASUREMENTS The CSAMT data are collected by measuring the magnitude and phase of the electric and magnetic fields. Measurements are made at discrete frequencies in binary steps. The receiver measures the magnitude of the received signal and the absolute phase difference between the received signal and the transmitted signal, which is known via synchronization of the transmitter and receiver. The measured data are stored in the receiver memory and output in ASCII format data files Data were acquired with Zonge model GDP-32II receivers, serial numbers 3252, 3238, and 3220. These instruments are backpack-portable, 16 bit, microprocessor-controlled receivers that can gather data on as many as eight channels. The electric-field signal was measured at the receiver site using non-polarizing ceramic Cu-CuSO4 porous-pot electrodes connected to the receiver with insulated 14-gauge wire. CSAMT magnetic-field measurements were made with Zonge ANT/6 antenna coils, serial numbers 246 and 276. The signal source for the CSAMT measurements was a Zonge GGT-30 transmitter, serial number 2094. The GGT-30 is a constant-current 30 KVA transmitter. Power for the transmitter was provided by a Zonge ZMG-30DL motor-generator equipped with a built-in voltage regulator. An XMT-32 transmitter controller, serial number 4148, controlled the transmitter. Transmitter-receiver synchronization was maintained with identical crystal oscillators, synchronized each morning before data acquisition. DATA PROCESSING Routine data processing consists of the following steps: 1) Initial log-log plots are reviewed to evaluate the data. 2) Data identified as spurious by the operator or individual measurements that are obvious outliers with respect to multiple repeat measurements are flagged and removed from further processing. 3) Raw data files (.raw) are processed via the CSAVGW program to produce an intermediate (.zdb) file. Corrections for polarity or calibration errors are made at this step. The output (.zdb) file has a single record containing all data for each individual stack or data block taken for each data channel. 4) The individual measurements (stacks) are averaged for each channel in the CSAVGW program and output in a column-based ASCII file (.avg) with a single averaged value for each parameter for each channel (station). 5) The average data are processed with the ASTATIC algorithm. Individual sounding curves are viewed and final removal of individual measurements that are considered to be affected by coherent noise is made. Log-log plots and the parametric pseudosections are generated at this step.

DATA QUALITY Data quality is monitored in the field by the operator. Real-time standard-error values are displayed during acquisition. In addition, multiple measurements at a range of frequencies are displayed graphically as resistivity versus frequency curves with error bars showing the data scatter. This allows a visual evaluation of the data quality and remedial action to be taken if necessary. Data quality is also evaluated during post-acquisition processing by reviewing data component plots Data are edited to remove spurious data if necessary. The data for this survey are of good quality, with repeated measurements generally within 5 percent. The smooth nature of the curves and lack of noticeable error bars, demonstrates good data quality. DATA PRESENTATION Line and transmitter locations are shown on a topographic base. Measured CSAMT data for each line are presented in color pseudosections of Cagniard resistivity and impedance phase with posted values. The posted values of apparent resistivity and impedance phase provide a written record of the basic CSAMT measurements. These plots are included as page-size plots in Appendix E and as image files on the Data CD-ROM. Digital data files and plots are included on a CD-ROM. See the file named readme.pdf on the data disk for a description of contents. SAFETY AND ENVIRONMENTAL ISSUES No health, safety incidents or accidents occurred during the course of this survey. No environmental damage was sustained as a direct result of the survey progress. Vehicle travel was kept to existing roads.

PRODUCTION LOG:

Date Notes

12/4/2011 Setup transmitter bipole. GDP 3252: Line 58530N. GDP 3238: Line 58330N

12/5/2011 GDP 3252T: line 58530N. GDP 3238: line 58330N

12/6/2011 GDP 3238: lines 58330N - 58130N

12/7/2011 GDP 3238: line 58130N. GDP 3220: line 57930N. Tore-down transmitter bipole.

APPENDIX B

PROPOSED DRILL HOLES & RESISTIVITY SECTIONS

FIGURE B1: Proposed Hole P4

FIGURE B2: Proposed Hole P5

redrock property csamt survey - atokagold.com · csamt work, reported upon by wright (2010, 2011a,...

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