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Geophysical Division

GEOPHYSICAL SURVEY FOR EXPLORATION OF METALLIC MINERAL IN THE
PRECAMBRAIN SHIELD ROCKS IN THE PUNJAB


The Precambrian shield rocks are the main building blocks of crust and are directly in contact with the upper mantle and might have experienced in the past attacks of volatile materials and hydrothermal solution carrying different metallic mineral deposits in zones of weakness/fault plans present in the shield rocks. The Precambrian shield rocks in many countries are host for metallic minerals. About 75% of World’s nickel is being mined from a large intrusive body in the Canadian Shield. In Pakistan, the shield rocks of Precambrian age are exposed in the Punjab near Sargodha, Chiniot, Sangla Hill and Shahkot areas. Economic minerals deposits of iron ore have been discovered in Chiniot and Rajoa areas in District Chiniot. The estimated reserves of Chiniot and Rajoa are 110 and 500 million tons, respectively. These deposits have been discovered in the Pre-Cambrian Indian Shield which is exposed in the Punjab in Districts Sargodha, Chiniot, Faisalabad and Sheikhupura. The discovery of Chiniot iron ore deposits has strengthened the idea that these rocks are mineralized in Pakistan also.

Geological Survey of Pakistan carried out ground magnetic survey in collaboration with Mines and Minerals Department, Government of Punjab for the Exploration of Metallic Minerals in the Pre-Cambrian Shield Rocks in the Punjab. Geophysical ground magnetic survey commenced from toposheets 43-D/12 and 43D/16, northern part of the project area. During the period August to October 2013, four toposheets 43D/12, 43D/16, 44A/9 and 44A/13 have been covered (1st phase). During November 2013 to January 2014 second phase started and in this phase seven toposheets 44E/1, 44 E/2, 44 E/3, 44 A/14, 44 A/15, 44 E6, and 44 E/7 were covered. Total field magnetic data was recorded by using Proton Precession Magnetometer Geometric G-856AX along traverses, Canals/ Distributaries Banks and accessible tracks.

Approved Cost: Rs. 53.1 million

Area Covered: 18,000 sq km

Total Toposheets: 28

1st Phase Toposheets: 4

2nd phase Toposheets: 7
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Seven anomaly zones were demarcated for further investigation in which integrated geophysical methods will be used. The selected anomalous localities will be recommended for exploratory drilling for confirmation/assessment of depth, dimensions and economic potential of the prospective zones

GROUND PENETRATION RADAR SURVEY
BENAZIR BHUTTO SHAHEED INTERNATIONAL AIRPORT ISLAMABAD


At Benazir Bhutto Shaheed International Airport Islamabad, GPR data was acquired by 800 Mhz frequency antenna. The depth of penetration is limited to less than a meter. Seven GPR profiles across the main runway, secondary and apron of the Benazir Bhutto Shaheed International Airport, Islamabad were observed. The aim of the survey was to check the thickness of different layers of runway and apron etc. the different layer with specific thickness are clearly evident from the GPR section along different GPR profiles like binder, base and base coarse. Below the base coarse, the data could not be acquired due to limited penetration of the said antenna.




GSP - AL TUWIRQI



In response to the request by M/S Al Tuwirqi Steel Mills (Pvt) the Geological Survey of Pakistan carried out ground magnetic survey in Juzzak Block, District Chagai Balochistan in November 2008. The primary objective of the ground survey was subsurface mapping for detection of magnetic anomalies indicating mineralization corroborating with the anomalies as interpreted on the aeromagnetic anomaly maps. Juzzak is located at the extreme South-West corner of Pakistan (Fig: 1). The project area falling within latitude 28º 47.596´ to 28º 33.89´ and longitude 61º 49.656´ to 62º 12.513´. Two prospective aeromagnetic sites 39 A, B, C and 38 have been covered in Juzzak and Warachah Kaur area.

Aeromagnetic anomaly 39 was further resolved in to three anomalies after careful analysis of the aeromagnetic anomaly map 1:250,000. Although the amplitude of the anomalies as intercepted in the Juzzak Block are not very high as compared to the magnetic anomalies encountered other part of Chagai district. An interesting feature is the locations of the anomalies are adjacent to faults interpreted on the aeromagnetic maps, which are considered promising for the mineral exploration. These aeromagnetic anomalies were covered by 100X100 meter grid and detailed profile across the anomaly’s center at 50 meters interval was observed for modeling with higher data control and resolution.

The investigated areas falls in Survey of Pakistan quadrangles 30 K and L. Ground magnetic measurements of 2850 stations were made to cover the target anomalies in the area. The sites were reconnoitered by initial traverses across the anomaly centers and subsequently covered by 100X100 meters grid. Results have been presented in the form of profiles and contour maps after necessary correction and reduction of field data. Location maps of respective sites along with the magnetic profiles on the grid lines have been given in annexure. After analysis of the results, test hole has been recommended at promising the site for appraisal of subsurface mineral potential.

ZIARAT

The geological and tectonic legacy of Balochistan has endowed it with massive mountain belts. Arcs, syntaxes and severe bending of the mountain belts under the process of convergence between the Indo-Pakistan and Eurasian plates mainly during the Tertiary period but still ongoing and transforming the topography and geomorphic features in the region. The seismic hazard zone map of Pakistan compiled by the GSP based on the recorded instrumental earthquake data of the Pakistan Meteorological Department juxtaposed with the tectonic map outlines Quetta and surroundings Lat 27.5º – 31º and long 65º -70º in the moderate to severe damage zone. The role of the ongoing tectonics in Balochistan was observed, assessed and highlighted by massive research contributions from home and abroad substantiating that northern Balochistan is a highly seismically active and tectonically unstable region defined as the Quetta Transverse/convergence zone incorporating the Quetta – Kalat fault, Sibi Re-entrant and specific areas in proximity to the regional faults.
The area sandwiched by the north–south trending Kirthar -Brahui ranges (south of Quetta) and the Sulaiman ranges (east of Quetta) with the locations of Quetta, Kach, Wam, Kuchlagh, Zarand, Kwas, Kan Bangla, Varchoom, Kohlu, Barkhan, Loralai, Harnai, Khost, Sharig, Ahmadun, Pishin, Khanozai, Khanai and areas in proximity to the Sibi Re -entrant all lie in the major convergence zone and prone to major seismic hazard.

The recent eruptive /effusive vent activity on 27th January 2010 at the Tor Zawar Mountain at Sari, Ziarat Balochistan is a manifestation and substantiation of the earlier risk and hazard findings for the region. As a unique event necessitating investigations, the Geological Survey of Pakistan accordingly planned and executed preliminary integrated geophysical surveys from last week of March, 2010 at the vent site to map detect and delineate the resultant changes in the lithological and structural disposition of the subsurface rocks arising due to the sloshing of the molten material through the vent. Results of the preliminary geophysical survey are presented in this report. The synthesis of the magnetic, resistivity soundings and profiling and ground penetration radar (GPR) survey indicate the presence of highly magnetic dual lobe sources, resistive and prominent reflectors from the radar soundings in and around the vent site.

The resistivity pseudo sections delineate the lateral and vertical molten flows which have apparently solidified at shallow depth. The GPR mapping due to ideal ground conditions has optimum penetration with high definition reflector topography, internal scatterers and hyperbolas. The radar imaging explicitly shows folding of the overlying fine grained clastics whereas fracturing in the compact, hard and brittle rock units of compact gravels/ limestone and volcanics due to the pressure exerted by the intrusion. The geological map of the study area (latitude 30º 15´ to 30º 45´ longitude 67º 15´ to 67º 45´) characterizes the presence of older volcanic rocks which are remnants of past volcanic episodes. This makes it rather difficult to further resolve the present geophysical findings that whether the subsurface discordant features/intrusives mapped are the result of solely the present day volcanic activity or the resultant effect incorporating both the older volcanics remelting and fusion with the present day ascending hydrothermal solution/magma.

However, based on the present survey the eruptive activity appears as an interactive play and involvement of the older volcanics, ascending magma from depth and dual tectonic-magmatism generating the eruptive activity. The epicentral/focal locations and migration of the past and present events in the area strongly suggest the role of regional tectonics and a positive connectivity of the weaker Sibi Re - entrant, Quetta -Kalat fault zone and the Quetta Transverse Zone. It is reckoned that the study area is prone to major seismic hazard from regional tectonics as well as hybrid events of seismo/volcano tectonic origin. Recommendations deemed mandatory have been made to study and monitor the site and surroundings for pre empting the vulnerability and risks in the area. It is hoped that the investigation at the vent site would probably be a prelude for further studies by the academic researchers and professional public and private sector institutions and other stakeholders.

STEEL MILL



Ground magnetic survey followed by gravity measurements to pin down an area to focus an exploration program for iron ore and to verify the occurrence of magnetite/ hematite mineralization within the survey area. Geological Survey of Pakistan conducted the ground aims to locate discrete or short length magnetic anomalies. Geometrics G-856 Proton Precision Magnetometer with a resolution of 0.001 nT, and a cycle rate of 0.1 second was used for data acquisition. The effective noise envelope was generally less than +/- 0.02nT. Garmin GPS 12XL and Magellan eXplorist XL Handheld GPS were used for spatial locations using WGS84 Datum.

For Topographic control and elevation determination Topcon Total Station was used. Ground magnetic Measurements were designed in two phases due to highly rugged topography of the surveyed block. In phase-1 measurements were taken along accessible tracks and traverses to demarcate anomalous zones, and in Phase-2 six anomalous zones were covered by regular grid pattern depending upon the dimensions of magnetic anomaly. Eight Magnetic profiles from all six potential zones have been selected to follow the gravity measurements. Gravity data supported magnetic anomalies both on over the mineralization zones as well as along the fault plane. All the collected data was reduced on local base within the area by making necessary correction and presented in the form of 2D contour maps and cross-sections, using computer software Surfer-9. After presentation of magnetic data qualitative interpretation was made and the results were compared with local geological data, which warranted that area has high potential of iron mineralization through solution filling along fault planes and fractures near contacts of Felsites and Diorite suites exposed in the surveyed area.

Neotectonics and Quantification of Seismic Deformation in Northern Pakistan

(Joseph Fourier University, Grenoble
&
University of Savoie, Chambery, France)
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View of GPS network in Northern Pakistan from Khunjrab top to Punjab Plains
The technical cooperation between Geological survey of Pakistan and Joseph Fourier University, Grenoble and University of Savoie, Chambery, France initiated just after 2005 earthquake starting from 2005 earthqauke affected areas and afterwards expanding to the Gilgit Baltistan ,Khyber Pakhtunkhawa,Azad Jammu and Kashmir, Potohar Plateau including Islamabad ,Salt range and Kirana hills in Punjab plains.

The 8th October, 2005 event is the first earthquake in the Himalaya with documented surface rupture. It is also the first large Himalayan earthquake since the advent of GPS Geodesy network system. Therefore, it was a unique opportunity to study great earthquakes in an intercontinental collision belt. After the earthquake, a GPS network was installed to monitor the postseismic displacements in earthquake affected areas and in other areas of Northern Pakistan. The monitoring strategy was defined in such a way as to identify the spatial and temporal evolution of the postseismic displacements and to take into account difficulties due to logistical and political constraints. Total 70 GPS control stations all over Pakistan have been installed in this project. The GPS stations are remeasured at equal intervals for data collection.


LANDSLIDE RISK ASSESSMENT & MITIGATION MEASURES (2006-2009)


(Norwegian Geotechnical Institute)

View of IT Lab established in GSP’s H-8 Office, Islamabad



One of the two landslides in Jhelum Valley selected for detailed study
Geological Survey of Pakistan signed a MoU with Norwegian Geotechnical Institute, the main objectives were the mapping of landslide hotspots in Muzaffarabad and the valleys along the affected area and selection of two hazardous sites for more detailed investigations.

GSP officials got trainings in GIS and numerical modelings from NGI. After a detailed fieldwork in Jhelum Valley, two landslides were selected for more detailed investigations. An Information Technology Laboratory was also established in the GSP’s H-8 Office, equipped with latest computers, GIS licenses, computers, scanners, plotter and a power generator.


A workshop arranged at Bangkok (Thailand) on October 13-14, 2008. The title of the workshop was “Experience of Geotechnical Investigations and Mitigation for Landslides”. Participants from Bangladesh, Bhutan, India, Nepal, Norway, Pakistan, Sri Lanka and Thailad shared their experiences related to the subject.