Mariana Files NI 43-101 Technical Report on Las Calandrias Project

VANCOUVER, BRITISH COLUMBIA -- (Marketwire) -- 08/25/11 -- Mariana Resources Ltd. (TSX: MRY)(AIM: MARL)(PLUS: MARL) ('Mariana' or 'the Company'), the AIM-quoted exploration and development company focused on Argentina and Chile, announces that it has filed on SEDAR a Technical Report compliant with National Instrument 43-101 ('the Technical Report'), the Canadian National Instrument for the Standards of Disclosure for Mineral Projects. The Technical Report entitled 'Technical Report on Gold and Silver Resources at Las Calandria - An Update Santa Cruz province Argentina' is related to the Company's Las Calandrias gold-silver project ('Las Calandrias') located in the prospective Deseado Massif gold district in the Santa Cruz province, southern Argentina and was written and compiled by Mine Development Associates ('MDA'), Reno, Nevada.

MDA concludes in the Technical Report that,

'The Las Calandrias property is an advanced-stage exploration property with a discovery of significant gold-silver mineralization and two defined resources of gold and silver whose classification is Indicated and Inferred. From a review of the data and field examination, it is concluded that Mariana has performed technical work that meets or exceeds industry standards.

Continued exploration is particularly warranted at Las Calandrias because of the existing resources and newly discovered mineralization in the country rock outside the rhyolite dome host rocks at Calandria Sur. In particular, the following exploration is planned for the coming months:

--  Drilling to test the geometry and continuity of mineralization in the
    volcaniclastic rocks adjacent to the Calandria Sur rhyolite dome on the
    north in the Loma Verde, La Picasa, and Vieja Herradura mineralized
    areas;

--  Drilling to test the continuity of high-grade mineralization in
    proximity to the andesite dike swarm at La Vieja Herradura;

--  Drilling to test extensions of the La Morena vein, a buried vein-breccia
    in the Calandria Norte dome, and to explore for the possible
    intersection of the La Morena vein with the La Calandria Vein Zone at
    depth;

--  Drilling to test a possible southwestern extension of the La Calandria
    Vein Zone vein-breccia into surrounding volcaniclastic rocks in the El
    Clavo vein trend that has been identified by mapping, trenching, and
    rock and lag sampling;

--  Drilling to test the margins of the Nido Este dome, located about 450m
    northwest of the center of the Calandria Norte dome, where recent lag
    and rock-chip sampling indicates anomalous gold and silver east of two
    holes drilled in 2008; and

--  Drilling to determine controls of mineralization, lateral continuity,
    and possible increase in grade with depth in the Nido Norte dome.

MDA recommends continuing exploration including rock-chip sampling, soil sampling, geophysics, diamond drilling, and metallurgy. Including technical staffing, camp logistics, water-well testing, community relations, and a 10% contingency, the total cost is US$4,075,000. With success in Phase I (defined as finding additional mineralization), more of similar types of work will be justified. Expectations would be that a similar sized budget would be justified.'

The Technical Report is available on the Company's website at http://www.marianaresources.com/pdf/reports/Mariana_LasCalandrias_2011_43-101.pdf

John Horsburgh, Chairman

Las Calandrias Project Background

Las Calandrias comprises multiple zones of gold mineralisation hosted by rhyolite domes over a 10.5 sq km area. In 2009, the first drilling programme (September-October) consisted of 16 scout holes (1,566m) testing the Calandria Norte vein-breccia and Calandria Sur dome breccia targets where significant gold mineralisation was discovered. The second drilling programme (March-April 2010) consisted of 4,400m in 37 holes and tested Calandria Sur (28 holes/3,212m); Calandria Norte (2 holes/299m), El Nido Este (2 holes/309m) and El Nido Norte (5 holes/580m). Phase three drilling (September-December 2010) consisted of 14,003m in 110 holes; Calandria Sur (56 holes/6,186m); Calandria Norte (43 holes/6,175m); Nido Norte (7 holes/1,054m); Nido Oeste (2 holes/421m); La Herradura (2 holes/168m). The continuity of phase three (January-April 2011) consisted of 15,736 m in 90 holes; Calandria Sur (6 holes/2,747m); Calandria Norte (21 holes/3,430); Despreciada: Nido Norte and Nido Centro (37 holes/6,414m); Nido Oeste (7 holes/1,130m); Nido Sur (18 holes/1,883 m); Gamekeeper (1 hole/132 m).

For further information please visit website at www.marianaresources.com.

About Mariana Resources

Mariana Resources Ltd is an AIM and TSX quoted exploration and development company with an extensive portfolio of gold, silver and copper projects in Argentina and Chile. In southern Argentina, in addition to the Las Calandrias gold-silver discovery, the Company has the Sierra Blanca silver-gold prospect (70%); the Los Amigos joint venture (49%) with Hochschild Mining and a 160,000 Ha land package (100%) in the country. All of these projects are located in the Deseado Massif epithermal gold-silver district in mining-friendly Santa Cruz province of southern Argentina, which hosts four mines and several advanced projects. In Chile, Mariana has a joint venture with US based international mining and natural resources company Cliffs Natural Resources Inc., to explore for iron oxide-copper-gold deposits ('IOCG') in a 92,000 km2 area ('SCM Mariana Area') in north-central Chile along the highly prospective Atacama Fault Zone. The SCM Mariana Area includes the 44km2 Buenaventura and 46km2 Perro Chico IOCG projects. Mariana is also evaluating a number of gold-silver and copper-gold opportunities away from the Cliffs JV area, as part of a new initiative.

Safe Harbour

This press release presents 'forward-looking statements' within the meaning of Canadian securities legislation that involve inherent risks and uncertainties. Forward-looking statements include, but are not limited to, statements with respect to the future price of gold and other minerals and metals, the estimation of mineral resources, the capital expenditures, costs and timing of the resources, the realization of mineral reserve estimates, the capital expenditures, costs and timing of the development of new deposits, success of exploration activities, permitting time lines, currency exchange rate fluctuations, requirements for additional capital, government regulation of mining operations, environmental risks, unanticipated reclamation expenses, title disputes or claims and limitations on insurance coverage. Generally, these forward-looking statements can be identified by the use of forward looking terminology such as 'plans', 'expects' or 'does not expect', 'is expected', 'budget', 'scheduled', 'estimates', 'forecasts', 'intends', 'anticipates' or 'does not anticipate', or 'believes', or variations of such words and phrases or state that certain actions, events or results 'may', 'could', 'would', 'might' or 'will be taken', 'occur' or 'be achieved'.

Forward-looking statements are subject to known and unknown risks, uncertainties and other factors that may cause the actual results, level of activity, performance or achievements of Mariana to be materially different from those expressed or implied by such forward looking statements, including but not limited to: risks related to international operations, actual results of current exploration activities; actual results of current or future reclamation activities; conclusions of economic evaluations; changes in project parameters as plans continue to be refined; future prices of gold and other minerals and metals; possible variations in ore reserves, grade or recovery rates; failure of equipment or processes to operate as anticipated; accidents, labour disputes and other risks of the mining industry; and delays in obtaining governmental approvals or financing or in the completion of development or construction activities. Although the management of Mariana believes that the expectations reflected in such forward-looking statements are based upon reasonable assumptions and have attempted to identify important factors that could cause actual results to differ materially from those contained in forward-looking statements, there may be other factors that cause results not to be as anticipated, estimated or intended. There can be no assurance that such statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements. Mariana Resources does not undertake to update any forward-looking statements that are incorporated by reference herein, except in accordance with applicable securities laws.

Incorporated in Guernsey registered number 44276

Neither the TSX nor its Regulation Services Provider (as that term is defined in the policies of the TSX Exchange) accepts responsibility for the adequacy or accuracy of this news release.

Contacts:

Mariana Resources Ltd.

John Horsburgh

Chairman

61 2 9437 4588


Mariana Resources Ltd.

Glen Parsons

CFO

61 2 9437 4588


Mariana Resources Ltd. (Vancouver Office)

Kathryn Witter

1 604 669 9336
www.marianaresources.com


RFC Corporate Finance Limited (Nomad)

Rob Adamson

61 2 9250 0041


RFC Corporate Finance Limited (Nomad)

Will Souter

61 2 9250 0050


FinnCap (Broker)

Matthew Robinson

44 20 7600 1658


Fox Davies Capital (Co UK Broker)

Jonathan Evans

44 20 3463 5000


St Brides Media and Finance Ltd (PR)

Felicity Edwards

44 20 7236 1177


St Brides Media and Finance Ltd (PR)

Hugo de Salis

44 20 7236 1177