Document:

BRIDGE LOAN AND CONTROL SHARE PLEDGE AND SECURITY AGREEMENT

      THIS BRIDGE LOAN AND CONTROL SHARE PLEDGE AND SECURITY AGREEMENT (this
"Agreement") is made this 1st day of September, 2005, by and among GRAN TIERRA
ENERGY INC., an Alberta corporation ("Borrower"), and GOLDSTRIKE, INC., a Nevada
corporation ("Lender").

                              W I T N E S S E T H:

      WHEREAS, Lender and Borrower have agreed upon the terms and conditions of
a merger (the "Merger") and related transactions (collectively, the
"Transactions"), as set forth in the Term Sheet attached hereto as Exhibit A
(the "Term Sheet"); and

      WHEREAS, simultaneously herewith Lender has consummated a private
placement offering (the "PPO") of units of its securities, which PPO was
conducted pursuant to the exemption from registration provided by Rule 506 of
Regulation D under the Securities Act of 1933, as amended (the "Securities Act")
and/or Section 4(2) of the Securities Act;

      WHEREAS, to provide Borrower with sufficient working capital to enable
Borrower to acquire certain Argentine oil and gas working interests (the
"Argentine Acquisition") while Lender and Borrower prepare the documentation
necessary and appropriate to consummate the Transactions and obtain all
necessary approvals from stockholders and third parties, Lender has agreed to
utilize the proceeds of the PPO to provide Borrower with a temporary loan;

      WHEREAS, in order to secure the Borrower's obligations under such loan
including, but not limited to, the Borrower's obligations under the Note and
Security Agreement (hereinafter referenced), each dated as of even date
herewith, the Borrower has agreed to issue and pledge to the Lender 13,114,285
shares of its common stock (the "Borrower Control Shares") which will constitute
51% of the outstanding capital stock of Borrower, on a fully-diluted basis;

      NOW, THEREFORE, in consideration of the premises and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, Borrower and the Lenders, intending to be legally bound, agree as
follows:

                                ARTICLE I - LOAN

      1.1. Loan. Lender agrees, on the terms and conditions of this Agreement,
to make loans to Borrower in an amount up to the entire proceeds of the PPO (the
"Commitment"), subject to the further terms hereof. Upon the execution and
delivery of this Agreement, the Lender shall loan to Borrower the amount of
Seven Million Dollars ($7,000,000), together with such adjustments for closing
and other expenses relating to the Argentine Acquisition as the parties may
mutually agree (the "Initial Amount"). The balance of the Commitment may be
drawn down by Borrower, in its discretion, upon compliance with the conditions
set forth in Exhibit B. The Initial Amount, together will all other amounts
borrowed hereunder, is sometimes hereinafter referred to as the "Loan".
<PAGE>

      1.2. The Note. Borrower has authorized the issuance of a promissory note
(the "Note") made in favor of Lender by Borrower, which shall be in the form set
forth in Exhibit B attached hereto. The Loan shall bear interest at the rate of
nine percent (9%) per annum on the full amount of the Commitment, regardless of
the actual amount borrowed by Borrower, and shall be due and payable to the
order of Lender 120 days after the date hereof (the "Due Date"); provided,
however, that from and after an Event of Default, as defined in Article VI
hereof, such interest rate shall increase to fifteen percent (15%) per annum.

      1.3. Payments. Borrower will begin making consecutive monthly interest
only payments on the Loan of accrued interest commencing thirty (30) days the
date hereof and continuing through the Due Date, at which time Borrower shall
repay the unpaid principal amount of the Loan, together with accrued and unpaid
interest; provided, that upon the closing of the Merger, all amounts outstanding
under the Loan shall be forgiven, and the Note shall be deemed repaid in full.

                              ARTICLE II - SECURITY

      As collateral security for Borrower's obligations hereunder and under the
Note, Borrower and each of Borrower's Subsidiaries will grant and pledge a
security interest in all of its respective assets to Lender, upon the terms and
conditions of a Security Agreement in the form set forth in Exhibit C attached
hereto, which is being executed and delivered simultaneously herewith. As an
additional inducement to Lender to make the Loan hereunder, the Borrower will
pledge the Borrower Control Shares, as provided for below. All certificates
representing Borrower's equity ownership of its Subsidiaries, together with all
certificates representing the Borrower Control Shares, shall be deposited into
escrow pursuant to the Pledge and Escrow Agreement (the "Escrow Agreement")
being executed simultaneously herewith

      For purposes of this Agreement, a "Subsidiary" means any corporation,
partnership, joint venture or other entity in which Borrower has, directly or
indirectly, an equity interest representing 50% or more of the capital stock
thereof or other equity interests therein.

                      ARTICLE III - BORROWER CONTROL SHARES

      3.1 Rights Relating to Borrower Control Shares. Prior to the occurrence of
an Event of Default (as defined herein) and the expiration of the applicable
Cure Period, (i) the Lender shall have no right to vote the Borrower Control
Shares at any meeting of the Borrower's stockholders, and (ii) the Lender shall
have no right to assign or transfer the Borrower Control Shares. Upon the
occurrence of such an Event of Default and the continuance thereof following the
expiration of the applicable Cure Period, the Lender shall be entitled (X) to
vote the Borrower Control Shares, and (Y) to assign or transfer such Borrower
Control Shares, and to enjoy all other rights and privileges incident to the
ownership of the Borrower Control Shares. Lender shall credit against the
amounts owed on the Loan, any dividends or distributions received with respect
to the Borrower Control Shares, and any proceeds received from the sale or
disposition of the Borrower Control Shares.

                                       2
<PAGE>

      3.2 Release of Pledged Shares from Pledge and Borrower Control Shares from
Escrow. Upon the payment of all amounts due to the Lender under the Loan
Documents by repayment in accordance with the terms of the Note, the parties
hereto shall notify the Escrow Agent to such effect in writing. Upon receipt of
such written notice, the Escrow Agent shall return to the party designated in
the notice the Transfer Documents and the certificates representing the Borrower
Control Shares. Notwithstanding anything to the contrary contained herein, upon
full payment of all amounts due to the Lender under the Loan Documents, by
repayment in accordance with the terms of the Note, this Agreement and Lender's
security interest and rights in and to the Borrower Control Shares shall
terminate.

             ARTICLE IV - REPRESENTATIONS AND WARRANTIES OF BORROWER

      Borrower represents and warrants as follows:

      4.1. Organization. Borrower is a corporation duly existing under the laws
of its jurisdiction of incorporation and qualified and licensed to do business
in any jurisdiction in which the conduct of its business or its ownership of
property requires that it be so qualified, except where the failure to be so
qualified would not have a material adverse effect on the business, operations,
condition (financial or otherwise), property or prospects of Borrower or any
Subsidiary, or the ability of Borrower or any Subsidiary to carry out their
respective obligations under the Loan Documents (as defined in Section 4.2
below) (a "Company Material Adverse Effect").

      4.2. Authorization. All corporate action on the part of Borrower and its
Subsidiaries and their respective officers, directors and stockholders necessary
for the authorization, execution, delivery and performance of all obligations of
Borrower and each such Subsidiary under this Agreement, the Note, the Security
Agreement, the Escrow Agreement and all other documents necessary or desirable
in connection with the Loan (collectively, the "Loan Documents") to which any of
them may be a party have been taken. This Agreement, the Notes, and the Security
Agreement, when executed and delivered by Borrower and each such Subsidiary,
shall constitute legal, valid and binding obligations of Borrower and each such
Subsidiary, enforceable against Borrower and each such Subsidiary in accordance
with their terms, except as such enforceability may be limited by applicable
bankruptcy, insolvency, moratorium or similar laws affecting creditors' rights
and the enforcement of debtors' obligations generally and by general principles
of equity, regardless of whether enforcement is pursuant to a proceeding in
equity or at law.

                                       3
<PAGE>

      4.3. Absence of Conflicts. The execution, delivery and performance of this
Agreement is not in conflict with nor does it constitute a breach of any
provision contained in Borrower's organizational documents, nor will it
constitute an event of default under any material agreement to which Borrower is
a party or by which Borrower is bound.

      4.4. Consents and Approvals. Borrower has obtained all consents, approvals
and authorizations of, made all declarations or filings with, and given all
notices to, all governmental authorities and agencies that are necessary for the
continued operation of Borrower's business as currently conducted, or are
required by law.

      4.5. Capitalization. The authorized and outstanding share capital of
Borrower is described on Schedule 4.5 attached hereto. Except as set forth on
Schedule 4.5 or as contemplated by the Transactions, there are no subscriptions,
convertible securities, options, warrants or other rights (contingent or
otherwise) currently outstanding to purchase any of the authorized but unissued
capital stock of Borrower. Except as set forth in Schedule 4.5 or as
contemplated by the Transactions, Borrower has no obligation to issue shares of
its capital stock, or subscriptions, convertible securities, options, warrants,
or other rights (contingent or otherwise) to purchase any shares of its capital
stock or to distribute to holders of any of its equity securities, any evidence
of indebtedness or asset. No shares of Borrower capital stock are subject to a
right of withdrawal or a right of rescission under any applicable securities
law. Except as set forth in Schedule 4.5, there are no outstanding or authorized
stock appreciation, phantom stock or similar rights with respect to the
Borrower. To the Knowledge of the Borrower, except as described in Schedule 4.5
or otherwise contemplated by this Agreement, there are no agreements to which
the Borrower is a party or by which it is bound with respect to the voting
(including without limitation voting trusts or proxies), registration under any
applicable securities laws, or sale or transfer (including without limitation
agreements relating to pre-emptive rights, rights of first refusal, co-sale
rights or "drag-along" rights) of any securities of the Borrower. To the
Knowledge of the Borrower, there are no agreements among other parties, to which
the Borrower is not a party and by which it is not bound, with respect to the
voting (including without limitation voting trusts or proxies) or sale or
transfer (including without limitation agreements relating to rights of first
refusal, co-sale rights or "drag-along" rights) of any securities of the
Borrower.

      4.6. Litigation. Except as disclosed on Schedule 4.6, there are no
actions, suits, claims, investigations, arbitrations or other legal or
administrative proceedings, to the Knowledge of Borrower, threatened against
Borrower at law or in equity, and to Borrower's Knowledge, there is no basis for
any of the foregoing. Except as disclosed on Schedule 4.6, there are no
unsatisfied judgments, penalties or awards against or affecting Borrower or its
businesses, properties or assets. Except as disclosed on Schedule 4.6, Borrower
is not in default, and no event has occurred which with the passage of time or
giving of notice or both would constitute a default by Borrower with respect to
any order, writ, injunction or decree known to or served upon Borrower of any
court or of any foreign, federal, state, municipal or other governmental
department, commission, board, bureau, agency or instrumentality, domestic or
foreign. Except as disclosed on Schedule 4.6, there is no action or suit by
Borrower pending or threatened against others. Except as disclosed on Schedule
4.6, Borrower has complied with all laws, rules, regulations and orders
applicable to its current business, operations, properties, assets, products and
services the violation of which would have a material adverse effect. There is
no existing law, rule, regulation or order, and Borrower has no Knowledge of any
proposed law, rule, regulation or order, whether foreign, federal or state, that
would prohibit or materially restrict Borrower from, or otherwise materially
adversely affect Borrower in, conducting its businesses in any jurisdiction in
which it is now conducting business.

                                       4
<PAGE>

      As defined in this Agreement, "Knowledge" of Borrower means the actual
knowledge by a director or officer of Borrower of a particular fact or
circumstance or such knowledge as may reasonably be imputed to such person as a
result of his actual knowledge of other facts or circumstances as well as any
other knowledge which such person would have possessed had they made reasonable
inquiry of appropriate employees and agents of Borrower with respect to the
matter in question.

      4.7. Absence of Certain Events. To the Borrower's Knowledge, there is no
existing condition, event or series of events which reasonably would be expected
to have a Company Material Adverse Effect.

      4.8 Title to Property and Assets. Borrower does not own any real property.
Except as set forth on Schedule 4.8, Borrower has good and marketable title to
all of its personal property and assets free and clear of any material
restriction, mortgage, deed of trust, pledge, lien, security interest or other
charge, claim or encumbrance which would have a material adverse effect. Except
as set forth on Schedule 4.8, with respect to properties and assets it leases,
Borrower is in material compliance with such leases and holds a valid leasehold
interest free of any liens, claims or encumbrances which would have a material
adverse effect.

      4.9. Governmental Permits. Borrower (including its Subsidiaries) holds all
licenses, franchises, permits and other governmental authorizations which are
required for the conduct of any aspect of Borrower's (including its
Subsidiaries') business, as presently conducted and as presently contemplated to
be conducted, including, but not limited to, all such business operations
contemplated by, or incident to, the Transactions and the Argentine Acquisition.
All such licenses, franchises, permits and other governmental authorizations are
valid and current, and Borrower has not received any notice that any
governmental authority intends to cancel, terminate or not renew any such
license, franchise, permit or other governmental authorization. Borrower has
conducted and is conducting its business in compliance with the requirements,
standards, criteria and conditions set forth in such licenses, franchises,
permits and other governmental authorizations, and all laws and regulations
applicable thereto, and is not in violation of any of the foregoing. The
consummation of the transactions contemplated hereunder will not alter or impair
or require changes to any such license, franchise, permit or other governmental
authorization.

                                       5
<PAGE>

      4.10 Borrower Control Shares. The Borrower Control Shares have been duly
and validly authorized for issuance and pledge pursuant to this Agreement and,
when issued and delivered as provided hereunder, will be duly authorized,
validly issued, fully paid and non-assessable and free and clear of all Liens
imposed by the Borrower or any other person other than restrictions on transfer
provided for in the Loan Documents. As used in this Agreement "Lien" means a
lien, charge, security interest, right of first refusal, preemptive right,
mortgage, pledge, title retention device, or other encumbrance or restriction.

                        ARTICLE V - COVENANTS OF BORROWER

      So long as the Note is outstanding, Borrower agrees that, unless Lender
shall give its prior consent in writing, which consent shall not be unreasonably
withheld:

      5.1. Ordinary Course. Borrower shall carry on its business in the ordinary
course substantially as conducted heretofore, and shall not engage in any
transaction outside of the ordinary course of business.

      5.2. Maintain Properties. Borrower shall maintain its properties and
facilities in good working order and condition, reasonable wear and tear
excepted.

      5.3. Performance under Agreements. Borrower shall perform all of its
obligations under agreements relating to or affecting its assets, properties or
rights.

      5.5. Cooperation with Lender. Borrower shall cooperate with Lender and
shall use its reasonable best efforts to complete and sign the merger agreement
(the "Merger Agreement") contemplated by the Merger and shall use its reasonable
best efforts to consummate the Transactions contemplated thereby.

      5.5. Financial Statements. Borrower shall provide to Lender prior to the
Due Date any such audited or unaudited financial statements as may be required
under applicable U.S. Securities Exchange Commission ("SEC") regulations for
inclusion of such statements in Lender's SEC and other regulatory filings upon
and following the Closing of the Merger.

      5.6. Maintenance of Business Organization. Borrower shall maintain and
preserve its business organization intact and use its best efforts to retain its
present key employees and relationships with suppliers, customers and others
having business relationships with Borrower.

      5.7. Compliance with Permits. Borrower shall maintain compliance with all
permits, laws, rules and regulations, consent orders and all other orders of
applicable courts, regulatory agencies, and similar governmental authorities.

      5.8. Leases. Borrower shall maintain its present leases in accordance with
their respective terms, and shall not enter into new or amended lease
instruments.

                                       6
<PAGE>

      5.9. Payments. Except with respect to fees due to attorneys, accountants,
and investment bankers relating to the Transactions, including with respect to
the Loan, Borrower shall not make any payment, or incur any obligation to make
any payment in the ordinary course of business in excess of $25,000 without the
prior written consent of the Lender.

      5.10. Loan Documents. Borrower shall comply in all respects with the terms
of the Security Agreement and all other Loan Documents.

      5.11. Indebtedness. Except as contemplated by the Argentine Acquisition,
Borrower shall not incur any indebtedness other than: (i) trade debt incurred in
the ordinary course of business, (ii) purchase money obligations in the ordinary
course of business up to $25,000, or (iii) taxes and assessments not delinquent
or actively being contested in good faith by Borrower and for which Borrower has
adequate reserves

      5.12. Liens. Borrower shall not permit to exist against any of its assets
any Lien except for (i) Permitted Liens (as defined in the Security Agreement),
(ii) taxes and assessments not delinquent or actively being contested in good
faith by Borrower and for which Borrower has adequate reserves, or (iii)
deposits or pledges for goods or services made in the ordinary course of
business.

      5.13. Mergers. Except as contemplated by the Transactions, Borrower shall
not merge or consolidate with or into any other corporation, or sell, assign,
lease or otherwise dispose of or voluntarily part with the control (whether in
one transaction or in a series of related transactions) of assets (whether now
owned or hereafter acquired) having a fair market value of more than $25,000 at
the time(s) of transfer, or sell, assign or otherwise dispose of (whether in one
transaction or in a series of transactions) any of its accounts receivable
(whether now in existence or hereafter created) at a discount or with recourse,
to any person, except sales or other dispositions of assets in the ordinary
course of business.

      5.15. Issuance of Capital Stock. Except as contemplated by the
Transactions, Borrower shall not issue, or agree or commit to issue, any shares
of capital stock, or to issue or grant any option, warrant, security or other
rights (contingent or otherwise) to purchase or acquire shares of its capital
stock, or any bond, debenture or other instrument or obligation which has the
power to vote in respect to the corporate affairs and management of Borrower.
The foregoing restriction shall not be construed to limit Borrower's ability to
issue or agree to issue shares of its capital stock, or to issue or grant any
option, warrant, security or other rights (contingent or otherwise) to purchase
or acquire shares of its capital stock, or any bond, debenture or other
instrument or obligation to the extent such sale or issuance is necessary to
enable Borrower, with Lender's consent not to be unreasonably withheld or
delayed, to cure an Event of Default under Article VI.

                                       7
<PAGE>

      5.15. Charter Documents. Borrower shall not make any amendment to its
Certificate of Incorporation or its By-Laws.

      Within three (3) business days following Borrower's request for a waiver
of any provision of this Article V, the Lenders shall provide Borrower with
their response to such request.

                       ARTICLE VI - DEFAULTS AND REMEDIES

      6.1. An "Event of Default" occurs if:

            (a) Borrower defaults in the payment of any principal or interest of
the Note when the same shall become due, either by the terms thereof or
otherwise as herein provided; or

            (b) Borrower defaults in the performance or observance of any other
agreement, term or condition contained in the Note or the other Loan Documents;
or

            (c) Borrower shall default in the payment of any principal of, or
premium, if any, or interest on, any other indebtedness in excess of $25,000 or
obligation with respect to borrowed money after expiration of any grace or cure
period or shall default in the performance of any material term of any
instrument evidencing such Indebtedness or of any mortgage, indenture or
agreement relating thereto after expiration of any grace or cure period, and the
effect of such default is to cause or to permit the holder or holders of such
obligation to cause, such Indebtedness or obligation to become due and payable
prior to its stated maturity; or

            (d) The Merger shall not have closed by the Due Date; or

            (e) Borrower pursuant to or within the meaning of any Bankruptcy
Law:

                  (i) commences a voluntary case,

                  (ii) consents to the entry of an order for relief against it
in an involuntary case,

                  (iii) consents to the appointment of a Custodian of it or for
all or substantially all of its property,

                  (iv) makes a general assignment for the benefit of its
creditors, or

                  (v) is the debtor in an involuntary case which is not
dismissed within thirty (30) days of the commencement thereof, or

                                       8
<PAGE>

            (f) A court of competent jurisdiction enters an order or decree
under any Bankruptcy Law that:

                  (i) provides for relief against Borrower in an involuntary
case,

                  (ii) appoints a Custodian of Borrower for all or substantially
all of its property, or

                  (iii) orders the liquidation of Borrower,

            (g) A final judgment for the payment of money in an amount in excess
of $25,000 shall be rendered against Borrower (other than any judgment as to
which a reputable insurance company shall have accepted full liability in
writing) and shall remain undischarged for a period (during which execution
shall not be effectively stayed) of 20 days after the date on which the right to
appeal has expired;

            (h) Any representation or warranty made by Borrower in this
Agreement, any other Loan Document or in any other document or instrument
furnished in connection with the transactions contemplated hereby shall prove to
be materially false or incorrect on the date as of which made; or

            (i) An event shall occur or there exist facts or circumstances which
create or result in a Material Adverse Effect;

then upon the occurrence of any Event of Default described in paragraphs (e) or
(f), the unpaid principal amount of and accrued interest on the Note shall
automatically become due and payable, without presentment, demand, protest or
notice of any kind, all of which are hereby waived by Borrower.

      Upon the occurrence of any other Event of Default, Lender shall give
Borrower written notice of default. Borrower shall have seventy five (75) days
(the "Cure Period") after receipt of written notice of default from Lender to
cure said default. Borrower may cure the default prior to the expiration of the
Cure Period by (i) making payment in full to Lender of the entire principal
amount outstanding under the Note and all accrued interest thereon, together
with all other sums due thereunder and hereunder and (ii) Lender shall cause the
Escrow Agent to release the Borrower Control Shares to Borrower. During the Cure
Period Lender may not exercise the rights and remedies granted to it with
respect to the Collateral under the Loan Documents.

      Notwithstanding the foregoing, if an Event of Default is cured prior to
the end of the Cure Period (including, but not limited to, an Event of Default
pursuant to Section 6.1(d) above), Borrower shall use its best efforts to ensure
that the Merger and the Transactions are consummated.

                                       9
<PAGE>

      If the Event of Default is not cured by the end of the Cure Period, then
in addition to any other rights, powers and remedies permitted by law or in
equity, the Lender may, at its option, by notice in writing to Borrower, declare
the Note to be, and the Notes shall thereupon be and become, immediately due and
payable, together with interest accrued thereon and all other sums due
hereunder, without presentment, demand, protest or other notice of any kind, all
of which are waived by Borrower.

      Upon the continuance of any Event of Default after the expiration of the
applicable Cure Period, the holder of the Note may proceed to protect and
enforce its rights by an action at law, suit in equity or other appropriate
proceeding, whether for the specific performance of any agreement contained
herein or in the Note held by it, for an injunction against a violation of any
of the terms hereof or thereof, or for the pursuit of any other remedy which it
may have by virtue of this Agreement, the Security Agreement or pursuant to
applicable law. Borrower shall pay to the holder of the Notes upon demand the
reasonable costs and expenses of collection and of any other actions referred to
in this Article, including without limitation reasonable attorneys' fees,
expenses and disbursements.

      No course of dealing and no delay on the part of the holder of the Note in
exercising any of its rights shall operate as a waiver thereof or otherwise
prejudice the rights of such holders, nor shall any single or partial exercise
of any right, power or remedy preclude any other or further exercise thereof or
the exercise of any other right, power or remedy hereunder. No right, power or
remedy conferred hereby or by the Note on the holder thereof shall be exclusive
of any other right, power or remedy referred to herein or therein or now or
hereafter available at law, in equity, by statute or otherwise.

      6.2. For purposes of this Article, the following definitions shall apply:

      "Bankruptcy Law" means Title 11, U.S. Code or any similar federal or state
law for the relief of debtors, or equivalent law of a non-U.S. jurisdiction.

      "Custodian" means any receiver, trustee, assignee, liquidator or similar
official under any Bankruptcy Law.

                              ARTICLE VII - NOTICES

      All notices, requests and demands shall be given to or made upon the
respective parties hereto in writing, such address as may be designated by it in
a written notice to the other party. All notices, requests, consents and demands
hereunder shall be effective when duly deposited in the mails (by overnight
delivery by a nationally-recognized overnight courier service or by United
States or Canadian registered or certified mail, postage prepaid, return receipt
requested) with a copy via facsimile. Unless the parties designate otherwise,
notices should be addressed as follows:

                                       10
<PAGE>

If to Borrower:

         Gran Tierra Energy Inc.
         Tenth Floor, 10 - 8th Avenue S.W.
         Calgary, Alberta, Canada T2P 1G5
         Attn: Dana Coffield, President and Chief Executive Officer
         Facsimile: (403)537-7440

with a copy to:

         McGuireWoods LLP
         1345 Avenue of the Americas
         New York, NY 10105
         Attn: Louis W. Zehil, Esq.
         Facsimile: (212) 548-2175

If to Lender:

         Goldstrike Inc.
         1055 West Hastings Street, Suite 1980
         Vancouver, B.C. Canada V6E 2E9
         Attn: Dr. Ken Cai
         Facsimile: (604) 688-8030

with a copy to:

         Gottbetter & Partners, LLP
         488 Madison Avenue, 12th Floor
         New York, NY 10022
         Attn: Adam S. Gottbetter, Esq.
         Facsimile: (212) 400-6901

                          ARTICLE VIII - MISCELLANEOUS

      8.1. Governing Law. This Agreement shall be governed by and construed in
accordance with the laws of the State of New York, without regard to conflicts
of laws principles thereof.

      8.2. Amendment. This Agreement may be amended, modified or terminated only
by an instrument in writing signed by all parties.

      8.3. No Assignment. Neither this Agreement nor any right or obligation
provided for herein may be assigned by any party without the prior written
consent of the other parties.

      8.4. Successors. The terms and provisions of this Agreement shall be
binding upon and inure to the benefit of, and be enforceable by, the respective
successors and assigns of the parties hereto.

                                       11
<PAGE>

      8.5. Counterparts. The Agreement may be executed in any number of
counterparts, with the same effect as if all parties had signed the same
document. All such counterparts shall be deemed an original, shall be construed
together and shall constitute one and the same instrument. This Agreement may be
executed by facsimile signature.

      8.6. Construction. The language used in this Agreement shall be deemed to
be the language chosen by the parties to express their mutual intent, and no
rule of strict construction shall be applied against any party.

      8.8. Counterparts. The section headings contained in this Agreement are
inserted for convenience only and shall not affect in any way the meaning or
interpretation of this Agreement.

      8.8. Severability. Any term or provision of this Agreement that is invalid
or unenforceable in any situation in any jurisdiction shall not affect the
validity or enforceability of the remaining terms and provisions hereof or the
validity or enforceability of the offending term or provision in any other
situation or in any other jurisdiction. If the final judgment of a court of
competent jurisdiction declares that any term or provision hereof is invalid or
unenforceable, the parties agree that the court making the determination of
invalidity or unenforceability shall have the power to limit the term or
provision, to delete specific words or phrases, or to replace any invalid or
unenforceable term or provision with a term or provision that is valid and
enforceable and that comes closest to expressing the intention of the invalid or
unenforceable term or provision, and this Agreement shall be enforceable as so
modified.

                                       12
<PAGE>

      IN WITNESS WHEREOF, the parties hereto have caused this Bridge Loan
Agreement to be duly executed as of the day and year first above written.

                                            BORROWER:

                                            GRAN TIERRA ENERGY INC.

                                            By:
                                               --------------------------------
                                               Name:
                                               Title

                                            LENDER:

                                            GOLDSTRIKE INC.

                                            By:
                                               --------------------------------
                                               Name:
                                               Title

                                       13
<PAGE>

                                    EXHIBIT A

                                  [Term Sheet]

                                       14
<PAGE>

                                    EXHIBIT B

                             Conditions to Draw Down

      Borrower shall provide to Lender notice of its intention to draw down
funds, setting forth the amount to be drawn down and the date of funding (which
date shall be at least five (5) days following the date of receipt by the Lender
of the notice). The Lender agrees to advance such sums in accordance with
Borrower's notices, provided that at the time of each request, Borrower has
provided assurances acceptable to the Lender that there exists no Event of
Default under this Agreement or the other Loan Documents.

                                       15
<PAGE>

                                    EXHIBIT C

                              [Security Agreement]

                                       16SECURITY AGREEMENT

      THIS SECURITY AGREEMENT ("Agreement") is made and entered into as of the
1st day of September, 2005, by and between Gran Tierra Energy Inc., an Alberta
corporation (the "Borrower"), Gran Tierra Energy Argentina S.A. ("GTA"), an
Argentine corporation and a wholly-owned subsidiary of Borrower, and Goldstrike
Inc. ("Lender"), a Nevada corporation.

                                    RECITALS:

      The Borrower has issued and delivered or will issue and deliver to the
Lender a Secured Bridge Promissory Note in the principal amount of the
Commitment, as hereinafter defined, dated as of the date of this Agreement (the
"Note"). Pursuant to the Note, the Borrower has agreed to grant a security
interest in and to the Collateral (as defined in this Agreement) on the terms
and conditions set forth in this Agreement.

      NOW, THEREFORE, for and in consideration of the Debt (as defined in this
Agreement), and of the premises and intending to be legally bound, the parties
covenant and agree as follows:

      1. Definitions. In addition to the words and terms defined elsewhere in
this Agreement, the following words and terms shall have the following meanings,
unless the context otherwise clearly requires:

      "Accounts" shall have the meaning given to that term in the Code and shall
      include without limitation all rights of the Borrower or GTA, whenever
      acquired, to payment for goods sold or leased or for services rendered,
      whether or not earned by performance.

      "As-extracted Collateral" shall have the meaning given to that term under
      the Code.

      "Borrower Control Shares" shall have the meaning given to that term in the
      Bridge Loan Agreement.

      "Bridge Loan Agreement" shall mean the Bridge Loan and Control Share
      Pledge and Security Agreement by and between the Borrower and the Lender
      dated as of even date herewith.

      "Chattel Paper" shall have the meaning given to that term in the Code and
      shall include without limitation all writings owned by the Borrower or,
      whenever acquired, which evidence both a monetary obligation and a
      security interest in or a lease of specific goods.

<PAGE>

      "Code" shall mean the Uniform Commercial Code as in effect on the date of
      this Agreement and as amended from time to time, of the state or states
      having jurisdiction with respect to all or any portion of the Collateral
      from time to time.

      "Collateral" shall mean all tangible and intangible assets of Borrower or
      GTA, including, without limitation, collectively the Accounts,
      As-extracted Collateral, Chattel Paper, Deposit Accounts, Documents,
      Equipment, Fixtures, all oil and gas in and extracted from the area
      covered by the Argentine Acquisition (as such term is defined in the
      Bridge Loan Agreement), Borrower Control Shares, Subsidiary Securities,
      General Intangibles, Instruments, Intellectual Property, Inventory,
      Investment Property and Proceeds of each of them, as well as the meaning
      ascribed to that term in Section 2.

      "Commitment" shall have the meaning given to that term in the Bridge Loan
      Agreement.

      "Cure Period" shall mean the period of seventy-five (75) days following
      written notice by Lender to Borrower of an Event of Default; provided,
      however, that there shall be no Cure Period for an Event of Default under
      Sections 6(e) or 6(f) of the Bridge Loan Agreement.

      "Debt" shall mean (i) all indebtedness, both principal and interest, of
      the Borrower to the Lender now or after the date of this Agreement
      evidenced by the Note, (ii) all other debts, liabilities, duties and
      obligations of the Borrower to the Lender arising after the date of this
      Agreement contracted or incurred, whether arising under or in connection
      with the Loan Documents or arising under or in connection with any other
      agreement, instrument, or undertaking made by or for the benefit of the
      Borrower to or for the benefit of the Lender, (iii) all costs and expenses
      incurred by the Lender in the collection of any of the indebtedness
      described in this paragraph or in connection with the enforcement of any
      of the duties and obligations of the Borrower to the Lender described in
      this paragraph, including reasonable attorneys' and paralegals' fees and
      expenses, and (iv) all future advances made by the Lender for the
      maintenance, protection, preservation or enforcement of, or realization
      upon, the Collateral or any portion of the Collateral, including advances
      for storage, transportation charges, taxes, insurance, repairs and the
      like.

      "Deposit Accounts" shall have the meaning given to that term in the Code
      and shall include a demand, time, savings, passbook or similar account
      maintained with a bank, savings bank, savings and loan association, credit
      union, trust company or other organization that is engaged in the business
      of banking.

      "Documents" shall have the meaning given to that term in the Code and
      shall include without limitation all warehouse receipts (as defined by the
      Code) and other documents of title (as defined by the Code) owned by the
      Borrower or GTA, whenever acquired.

                                       2
<PAGE>

      "Equipment" shall have the meaning given to that term in the Code and
      shall include without limitation all goods owned by the Borrower or GTA,
      whenever acquired and wherever located, used or brought for use primarily
      in the business or for the benefit of the Borrower or GTA and not included
      in Inventory of the Borrower or GTA, together with all attachments,
      accessories and parts used or intended to be used with any of those goods
      or Fixtures, whether now or in the future installed therein or thereon or
      affixed thereto, as well as all substitutes and replacements thereof in
      whole or in part.

      "Escrow Agent" shall mean Gottbetter & Partners, LLP.

      "Escrow Agreement" shall mean the Pledge and Escrow Agreement among the
      Borrower, the Lender and the Escrow Agent with respect to the Pledged
      Shares and the Borrower Control Shares.

      "Event of Default" shall mean (i) any of the Events of Default described
      in the Note or the Loan Documents, or (ii) any default by the Borrower or
      GTA in the performance of its obligations under this Agreement.

      "Fixtures" shall have the meaning given to that term in the Code, and
      shall include without limitation leasehold improvements.

      "General Intangibles" shall have the meaning given to that term in the
      Code and shall include, without limitation, all leases under which the
      Borrower or GTA now or in the future leases and or obtains a right to
      occupy or use real or personal property, or both, all of the other
      contract rights of the Borrower or GTA, whenever acquired, and customer
      lists, choses in action, claims (including claims for indemnification),
      books, records, patents, copyrights, trademarks, blueprints, drawings,
      designs and plans, trade secrets, methods, processes, contracts, licenses,
      license agreements, formulae, tax and any other types of refunds, returned
      and unearned insurance premiums, rights and claims under insurance
      policies, and computer information, software, records and data, and oil,
      gas, or other minerals before extraction now owned or acquired after the
      date of this Agreement by the Borrower or GTA.

      "Instruments" shall have the meaning given to that term in the Code and
      shall include, without limitation, all negotiable instruments (as defined
      in the Code), all certificated securities (as defined in the Code) and all
      other writings which evidence a right to the payment of money now or after
      the date of this Agreement owned by the Borrower or GTA.

      "Inventory" shall have the meaning given to that term in the Code and
      shall include without limitation all goods owned by the Borrower, whenever
      acquired and wherever located, held for sale or lease or furnished or to
      be furnished under contracts of service, and all raw materials, work in
      process and materials owned by the Borrower and used or consumed in the
      Borrower's business, whenever acquired and wherever located.

                                       3
<PAGE>

      "Investment Property," "Securities Intermediary" and "Commodities
      Intermediary" each shall have the meaning set forth in the Code.

      "Know-How" means all documented and undocumented research, ideas, data,
      theories, conclusions, reports, drawings, designs, blueprints, schematics,
      exhibits, models, prototypes, source code, object code, flow charts,
      manuals, processes, specifications, formulae, product configurations,
      notes, inventions (whether or not patentable and whether or not reduced to
      practice) and any other information of any kind developed, in development
      or maintained by the Borrower or GTA or any of their respective employees,
      agents or representatives relating to any goods or services sold or
      licensed or offered for sale or license by the Borrower or GTA or goods or
      services which the Borrower or GTA has a present intention to sell or
      license.

      "Loan Documents" shall mean collectively, this Agreement, the Note, the
      Bridge Loan Agreement, the Escrow Agreement and all other agreements,
      documents and instruments executed and delivered in connection therewith,
      as each may be amended, supplemented or modified from time to time.

      "Permitted Liens" shall mean all (i) all existing liens on the assets of
      the Borrower or GTA which have been disclosed to the Lender by the
      Borrower in the Bridge Loan Agreement, and (ii) all purchase money
      security interests hereinafter incurred by the Borrower or GTA in the
      ordinary course of business to the extent permitted by the Bridge Loan
      Agreement.

      "Pledged Shares" shall mean the Borrower Control Shares and the Subsidiary
      Securities.

      "Proceeds" shall have the meaning given to that term in the Code and shall
      include without limitation whatever is received when Collateral or
      Proceeds are sold, exchanged, collected or otherwise disposed of, whether
      cash or non-cash, and includes without limitation proceeds of insurance
      payable by reason of loss of or damage to Collateral.

      "Subsidiary" means any corporation, partnership, joint venture or other
      entity in which the Borrower has, directly or indirectly, an equity
      interest representing 50% or more of the capital stock thereof or other
      equity interests therein.

      "Subsidiary Securities" means any Instruments representing or evidencing
      an equity interest in a Subsidiary.

      "Trade Secret Rights" means all documentation, Know-How and other
      materials owned by the Borrower or GTA that is considered to be
      proprietary to the Borrower or GTA, is maintained on a confidential or
      secret basis, and is generally not known to other persons or entities who
      are not subject to confidentiality restrictions.

                                       4
<PAGE>

      2. Security Interest. As security for the full and timely payment of the
Debt in accordance with the terms of the Debt and the performance of the
obligations of the Borrower under the Note and this Agreement, the Borrower and
GTA agree that the Lender shall have, and the Borrower and GTA grant and convey
to and create in favor of the Lender, a security interest under the Code in and
to such of the Collateral as is now owned or acquired after the date of this
Agreement by the Borrower or GTA. The security interest granted to the Lender in
this Agreement shall be a first priority security interest, prior and superior
to the rights of all third parties existing on or arising after the date of this
Agreement, subject to the Permitted Liens. Certain of the Collateral is
described on Exhibit A hereto, which Collateral is included in the Collateral.

      3. Provisions Applicable to the Collateral. The parties agree that the
following provisions shall be applicable to the Collateral:

      (a) The Borrower covenants and agrees that at all times during the term of
this Agreement it shall keep accurate and complete books and records concerning
the Collateral that is now owned or acquired after the date of this Agreement by
the Borrower or GTA.

      (b) The Lender or its representatives shall have the right, upon
reasonable prior written notice to the Borrower and GTA and during the regular
business hours of the Borrower and GTA, to examine and inspect the Collateral
and to review the books and records of the Borrower and GTA concerning the
Collateral that is now owned or acquired after the date of this Agreement by the
Borrower and to copy the same and make excerpts therefrom; provided, however,
that from and after the occurrence of an Event of Default, the rights of
inspection and entry shall be subject to the requirements of the Code.

      t 6 0 (c) The Borrower and GTA shall at all times during the term of this
Agreement keep the Equipment, Inventory and Fixtures that are now owned or
acquired after the date of this Agreement by the Borrower and GTA at its various
locations or, upon written notice to the Lender, at such other locations for
which the Lender has filed financing statements, and at no other location
without 20 days' prior written notice to the Lender, except that the Borrower
shall have the right until one or more Events of Default shall occur to sell or
otherwise dispose of Inventory and other Collateral in the ordinary course of
business.

      (d) The Borrower shall not move the location of its principal executive
offices without prior written notification to the Lender.

                                       5
<PAGE>

      (e) Without the prior written consent of the Lender, the Borrower and GTA
shall not sell, lease or otherwise dispose of any Equipment or Fixtures, except
in the ordinary course of their business.

      (f) Promptly upon request of the Lender from time to time, the Borrower
shall furnish the Lender with such information and documents regarding the
Collateral and the Borrower's financial condition, business, assets or
liabilities, at such times and in such form and detail as the Lender may
request.

            (g) At all times during the term of this Agreement, the Borrower
shall deliver to the Lender, upon its written request, without limitation,

            (i) all invoices and customer statements rendered to account
debtors, documents, contracts, chattel paper, instruments and other writings
pertaining to the Borrower's contracts or the performance of the Borrower's
contracts,

            (ii) evidence of the Borrower's accounts and statements showing the
aging, identification, reconciliation and collection thereof, and

      (iii) reports as to the Borrower's inventory and sales, shipment, damage
or loss thereof, all of the foregoing to be certified by authorized officers or
other employees of the Borrower, and Borrower shall take all necessary action
during the term of this Agreement to perfect any and all security interests in
favor of Borrower and to assign to Lender all such security interests in favor
of Borrower.

      (h) Notwithstanding the security interest in the Collateral granted to and
created in favor of the Lender under this Agreement, the Borrower shall have the
right until one or more Events of Default shall occur, at its own cost and
expense, to collect the Accounts and the Chattel Paper and to enforce its
contract rights.

      (i) Upon the continuance of an Event of Default following the expiration
of the applicable Cure Period, the Lender shall have the right, in its sole
discretion, to give notice of the Lender's security interest to account debtors
obligated to the Borrower or GTA and to take over and direct collection of the
Accounts and the Chattel Paper, to notify such account debtors to make payment
directly to the Lender and to enforce payment of the Accounts and the Chattel
Paper and to enforce the Borrower's or GTA's contract rights. It is understood
and agreed by the Borrower and GTA that the Lender shall have no liability
whatsoever under this subsection (i) except for its own gross negligence or
willful misconduct.

      (j) At all times during the term of this Agreement Borrower and GTA shall
promptly deliver to the Lender, upon its written request, all existing leases,
and all other leases entered into by Borrower or GTA from time to time, covering
any Equipment or Inventory ("Leased Inventory") which is leased to third
parties.

                                       6
<PAGE>

      (l) Neither the Borrower nor GTA shall change its name, entity status,
federal taxpayer identification number, or provincial organizational or
registration number, or the state under which it is organized without the prior
written consent of the Lender.

      (m) Neither the Borrower nor GTA shall close any of its Deposit Accounts
or open any new or additional Deposit Accounts without first giving the Lender
at least fifteen (15) days prior written notice thereof.

      (n) The Borrower and GTA shall cooperate with the Lender, at Borrower's
expense, in perfecting Lender's security interest in any of the Collateral,
including the execution of any control agreement(s) required in order to perfect
Lender's security interest in the Deposit Accounts.

      (o) Lender may file any necessary financing statements and other documents
Lender deems necessary in order to perfect Lender's security interest without
Borrower's signature. Borrower grants to Lender a power of attorney for the sole
purpose of executing any documents on behalf of Borrower which Lender deems
necessary to perfect Lender's security interest. Such power, coupled with an
interest, is irrevocable.

      (p) The parties agree that the Lender shall have the right to designate
and appoint a collateral agent to act for and on behalf of the Lenders with
respect to the Collateral under this Agreement, provided that Borrower is
notified in writing at least ten (10) days in advance of such appointment.

      4. Additional Provisions Applicable to the Pledged Shares.

      (a) Simultaneously herewith the Borrower has delivered to the Escrow Agent
one or more certificates representing the Pledged Shares, together with stock
powers duly executed in blank by the Borrower. The Escrow Agent shall hold such
Pledged Shares pursuant to the terms of the Escrow Agreement.

      (b) The Pledged Shares shall be held by the Escrow Agent as security for
the timely payment of all of the Borrower's obligations under the Note and for
the Borrower's performance of all of its obligations under this Agreement, as
provided herein.

      (c) The Escrow Agreement shall provide that while the Escrow Agent holds
the Pledged Shares as security, the Borrower shall have the right to vote the
Pledged Shares at all meetings of the Subsidiaries' stockholders to the same
extent as if such Pledged Shares were held by Borrower; provided that no Event
of Default has occurred and is continuing following the expiration of the Cure
Period and that the Borrower is not in default in the performance of any term of
this Agreement. In the event of any such a default or continuance of Event of
Default following the expiration of the Cure Period, the Lender shall have the
right to the extent permitted by law to vote and to give consents, ratifications
and waivers and take any other action with respect to the Pledged Shares with
the same force and effect as if the Lender were the absolute and sole owner of
the Pledged Shares.

                                       7
<PAGE>

      4. Actions with Respect to Accounts. The Borrower irrevocably makes,
constitutes and appoints the Lender its true and lawful attorney-in-fact with
power to sign its name and to take any of the following actions after the
occurrence and prior to the cure of an Event of Default, at any time without
notice to the Borrower and at the Borrower's expense:

      (a) Verify the validity and amount of, or any other matter relating to,
the Collateral by mail, telephone, telegraph or otherwise;

      (b) Notify all account debtors that the Accounts have been assigned to the
Lender and that the Lender have a security interest in the Accounts;

      (c) Direct all account debtors to make payment of all Accounts directly to
the Lender;

      (d) Take control in any reasonable manner of any cash or non-cash items of
payment or proceeds of Accounts;

      (e) Receive, open and dispose of all mail addressed to the Borrower;

      (f) Take control in any manner of any rejected, returned, stopped in
transit or repossessed goods relating to Accounts;

      (g) Enforce payment of and collect any Accounts, by legal proceedings or
otherwise, and for such purpose the Lender may:

            (1) Demand payment of any Accounts or direct any account debtors to
make payment of Accounts directly to the Lender;

            (2) Receive and collect all monies due or to become due to the
Borrower or GTA pursuant to the Accounts;

            (3) Exercise all of the Borrower's or GTA's rights and remedies with
respect to the collection of Accounts;

            (4) Settle, adjust, compromise, extend, renew, discharge or release
Accounts in a commercially reasonable manner;

            (5) Sell or assign Accounts on such reasonable terms, for such
reasonable amounts and at such reasonable times as the Lender reasonably deems
advisable;

            (6) Prepare, file and sign the Borrower's or GTA's name or names on
any Proof of Claim or similar documents in any proceeding filed under federal or
state bankruptcy, insolvency, reorganization or other similar law as to any
account debtor;

                                       8
<PAGE>

            (7) Prepare, file and sign the Borrower's or GTA's name or names on
any notice of lien, claim of mechanic's lien, assignment or satisfaction of lien
or mechanic's lien or similar document in connection with the Collateral;

            (8) Endorse the name of the Borrower or GTA upon any chattel papers,
documents, instruments, invoices, freight bills, bills of lading or similar
documents or agreements relating to Accounts or goods pertaining to Accounts or
upon any checks or other media of payment or evidence of a security interest
that may come into the Lender, possession;

            (9) Sign the name of the Borrower or GTA to verifications of
Accounts and notices of Accounts sent by account debtors to the Borrower or GTA;
or

            (10) Take all other actions that the Lender reasonably deems to be
necessary or desirable to protect the Borrower's or GTA's interest in the
Accounts.

      (h) Negotiate and endorse any Document in favor of the Lender or its
designees, covering Inventory which constitutes Collateral, and related
documents for the purpose of carrying out the provisions of this Agreement and
taking any action and executing in the name of Borrower or GTA any instrument
which the Lender may reasonably deem necessary or advisable to accomplish the
purpose hereof. Without limiting the generality of the foregoing, the Lender
shall have the right and power to receive, endorse and collect checks and other
orders for the payment of money made payable to the Borrower or GTA representing
any payment or reimbursement made under, pursuant to or with respect to, the
Collateral or any part thereof and to give full discharge to the same. The
Borrower and GTA ratify and approve all acts of said attorney and agree that
said attorney shall not be liable for any acts of commission or omission, nor
for any error of judgment or mistake of fact or law, except for said attorney's
own gross negligence or willful misconduct. This power, being coupled with an
interest, is irrevocable until the Debt is paid in full (at which time this
power shall terminate in full) and the Borrower and GTA shall have performed all
of their obligations under this Agreement. The Borrower and GTA further agree to
use their reasonable efforts to assist the Lender in the collection and
enforcement of the Accounts and will not hinder, delay or impede the Lender in
any manner in its collection and enforcement of the Accounts.

      5. Preservation and Protection of Security Interest. Each of the Borrower
and GTA represents and warrants that it has, and covenants and agrees that at
all times during the term of this Agreement, it will have, good and marketable
title to the Collateral from time to time owned or acquired by it free and clear
of all mortgages, pledges, liens, security interests, charges or other
encumbrances, except for the Permitted Liens and those junior in right of
payment and enforcement to that of the Lender or in favor of the Lender, and
shall defend the Collateral against the claims and demands of all persons, firms
and entities whomsoever. Each of the Borrower and GTA represents and warrants
that as of the date of this Agreement the Lender has, and that all times in the
future the Lender will have, a first priority perfected security interest in the
Collateral, prior and superior to the rights of all third parties in the
Collateral existing on the date of this Agreement or arising after the date of
this Agreement, subject to the Permitted Liens. Except as permitted by this

                                       9
<PAGE>

Agreement, each of the Borrower and GTA covenants and agrees that it shall not,
without the prior written consent of the Lender (i) borrow against the
Collateral or any portion of the Collateral from any other person, firm or
entity, except for borrowings which are subordinate to the rights of the Lender,
(ii) grant or create or permit to attach or exist any mortgage, pledge, lien,
charge or other encumbrance, or security interest on, of or in any of the
Collateral or any portion of the Collateral except those in favor of the Lender
or the Permitted Liens, (iii) permit any levy or attachment to be made against
the Collateral or any portion of the Collateral, except those subject to the
Permitted Liens, or (iv) permit any financing statements to be on file with
respect to any of the Collateral, except financing statements in favor of the
Lender or those with respect to the Permitted Liens. The Borrower and GTA shall
faithfully preserve and protect the Lender's security interest in the Collateral
and shall, at their own cost and expense, cause, or assist the Lender to cause
that security interest to be perfected and continue perfected so long as the
Debt or any portion of the Debt is outstanding, unpaid or executory. For
purposes of the perfection of the Lender's security interest in the Collateral
in accordance with the requirements of this Agreement, the Borrower and GTA
shall from time to time at the request of the Lender file or record, or cause to
be filed or recorded, such instruments, documents and notices, including
assignments, financing statements and continuation statements, as the Lender may
reasonably deem necessary or advisable from time to time in order to perfect and
continue perfected such security interest. The Borrower and GTA shall do all
such other acts and things and shall execute and deliver all such other
instruments and documents, including further security agreements, pledges,
endorsements, assignments and notices, as the Lender in its discretion may
reasonably deem necessary or advisable from time to time in order to perfect and
preserve the priority of such security interest as a first lien security
interest in the Collateral prior to the rights of all third persons, firms and
entities, subject to the Permitted Liens and except as may be otherwise provided
in this Agreement. The Borrower and GTA agree that a carbon, photographic or
other reproduction of this Agreement or a financing statement is sufficient as a
financing statement and may be filed instead of the original.

      6. Insurance. Risk of loss of, damage to or destruction of the Equipment,
Inventory and Fixtures is on the Borrower and GTA. The Borrower and GTA shall
insure the Equipment, Inventory and Fixtures against such risks and casualties
and in such amounts and with such insurance companies as is ordinarily carried
by corporations or other entities engaged in the same or similar businesses and
similarly situated or as otherwise reasonably required by the Lender in its sole
discretion. In the event of loss of, damage to or destruction of the Equipment,
Inventory or Fixtures during the term of this Agreement, the Borrower shall
promptly notify Lender of such loss, damage or destruction. At the reasonable
request of the Lender, each of the Borrower's or GTA's policies of insurance
shall contain loss payable clauses in favor of the Borrower or GTA and the
Lender as their respective interests may appear and shall contain provision for
notification of the Lender thirty (30) days prior to the termination of such
policy. At the request of the Lender, copies of all such policies, or
certificates evidencing the same, shall be deposited with the Lender. If the
Borrower or GTA fails to effect and keep in full force and effect such insurance
or fails to pay the premiums when due, the Lender may (but shall not be

                                       10
<PAGE>

obligated to) do so for the account of the Borrower or GTA and add the cost
thereof to the Debt. The Lender is irrevocably appointed attorney-in-fact of the
Borrower and GTA to endorse any draft or check which may be payable to the
Borrower or GTA in order to collect the proceeds of such insurance. Unless an
Event of Default has occurred and is continuing, the Lender will turn over to
the Borrower or GTA the proceeds of any such insurance collected by it on the
condition that the Borrower or GTA apply such proceeds either (i) to the repair
of damaged Equipment, Inventory or Fixtures, or (ii) to the replacement of
destroyed Equipment, Inventory or Fixtures with Equipment, Inventory or Fixtures
of the same or similar type and function and of at least equivalent value (in
the sole judgment of the Lender), provided such replacement Equipment, Fixtures
or Inventory is made subject to the security interest created by this Agreement
and constitutes a first lien security interest in the Equipment, Inventory and
Fixtures subject only to Permitted Liens and other security interests permitted
under this Agreement, and is perfected by the filing of financing statements in
the appropriate public offices and the taking of such other action as may be
necessary or desirable in order to perfect and continue perfected such security
interest. Any balance of insurance proceeds remaining in the possession of the
Lender after payment in full of the Debt shall be paid over to the Borrower or
GTA or its order.

      7. Maintenance and Repair. The Borrower and GTA shall maintain the
Equipment, Inventory and Fixtures, and every portion thereof, in good condition,
repair and working order, reasonable wear and tear alone excepted, and shall pay
and discharge all taxes, levies and other impositions assessed or levied thereon
as well as the cost of repairs to or maintenance of the same. If the Borrower or
GTA fails to do so, the Lender may (but shall not be obligated to) pay the cost
of such repairs or maintenance and such taxes, levies or impositions for the
account of the Borrower or GTA and add the amount of such payments to the Debt.

      8. Preservation of Rights Against Third Parties; Preservation of
Collateral in Lender's Possession. Until such time as the Lender exercise its
right to effect direct collection of the Accounts and the Chattel Paper and to
effect the enforcement of the Borrower's or GTA's contract rights, the Borrower
and GTA assume full responsibility for taking any and all commercially
reasonable steps to preserve rights in respect of the Accounts and the Chattel
Paper and their contracts against prior parties. The Lender shall be deemed to
have exercised reasonable care in the custody and preservation of such of the
Collateral as may come into its possession from time to time if the Lender takes
such action for that purpose as the Borrower or GTA shall request in writing,
provided that such requested action shall not, in the judgment of the Lender,
impair the Lender's security interest in the Collateral or its right in, or the
value of, the Collateral, and provided further that the Lender receives such
written request in sufficient time to permit the Lender to take the requested
action.

                                       11
<PAGE>

      9. Events of Default and Remedies.

      (a) If any one or more of the Events of Default shall occur or shall
exist, the Lender may upon the expiration of the applicable Cure Period or at
any time thereafter, so long as such default shall continue, foreclose the lien
or security interest in the Collateral in any way permitted by law, or upon
fifteen (15) days prior written notice to the Borrower and GTA, sell any or all
Collateral at private sale at any time or place in one or more sales, at such
price or prices and upon such terms, either for cash or on credit, as the
Lender, in its sole discretion, may elect, or sell any or all Collateral at
public auction, either for cash or on credit, as the Lender, in its sole
discretion, may elect, and at any such sale, the Lender may bid for and become
the purchaser of any or all such Collateral. Pending any such action the Lender
may liquidate the Collateral.

      (b) If any one or more of the Events of Default shall occur or shall
exist, the Lender may upon the expiration of the applicable Cure Period, or at
any time thereafter, so long as such default shall continue, grant extensions
to, or adjust claims of, or make compromises or settlements with, debtors,
guarantors or any other parties with respect to Collateral or any securities,
guarantees or insurance applying thereon, without notice to or the consent of
the Borrower or GTA, without affecting the Borrower's or GTA's liability under
this Agreement or the Note. Each of the Borrower and GTA waives notice of
acceptance, of nonpayment, protest or notice of protest of any Accounts or
Chattel Paper or any of its contract rights and any other notices to which the
Borrower or GTA may be entitled.

      (c) If any one or more of the Events of Default shall occur or shall exist
and be continuing following the expiration of the applicable Cure Period, then
in any such event, the Lender shall have such additional rights and remedies in
respect of the Collateral or any portion thereof as are provided by the Code and
such other rights and remedies in respect thereof which it may have at law or in
equity or under this Agreement, including without limitation the right to enter
any premises where Equipment, Inventory and/or Fixtures are located and take
possession and control thereof without demand or notice and without prior
judicial hearing or legal proceedings, which the Borrower and GTA expressly
waive.

      (d) The Lender shall apply the Proceeds of any sale or liquidation of the
Collateral, and, subject to Section 6, any Proceeds received by the Lender from
insurance, first to the payment of the reasonable costs and expenses incurred by
the Lender in connection with such sale or collection, including without
limitation reasonable attorneys' fees and legal expenses, second to the payment
of the Debt, whether on account of principal or interest or otherwise as the
Lender, in its sole discretion, may elect, and then to pay the balance, if any,
to the Borrower or as otherwise required by law. If such Proceeds are
insufficient to pay the amounts required by law, the Borrower shall be liable
for any deficiency.

      (e) Upon the occurrence of any Event of Default and such Event of
Default's continuance following the expiration of the applicable Cure Period,
the Borrower and GTA shall promptly upon written demand by the Lender assemble
the Equipment, Inventory and Fixtures and make them available to the Lender at a
place or places to be designated by the Lender. The rights of the Lender under
this paragraph to have the Equipment, Inventory and Fixtures assembled and made
available to it is of the essence of this Agreement and the Lender may, at its
election, enforce such right by an action in equity for injunctive relief or
specific performance, without the requirement of a bond.

                                       12
<PAGE>

      (f) Notwithstanding anything herein to the contrary, if an Event of
Default is cured prior to the end of the Cure Period (including, but not limited
to, an Event of Default pursuant to Section 6.1(d) of the Bridge Loan
Agreement), the Borrower shall use its best efforts to ensure that the Merger
and the Transactions, as such terms are defined in the Bridge Loan Agreement,
are consummated.

      10. Defeasance. Notwithstanding anything to the contrary contained in this
Agreement upon payment and performance in full of the Debt, this Agreement shall
terminate and be of no further force and effect and the Lender shall thereupon
terminate its security interest in the Collateral. Until such time, however,
this Agreement shall be binding upon and inure to the benefit of the parties,
their successors and assigns, provided that, without the prior written consent
of the Lender, neither the Borrower nor GTA may assign this Agreement or any of
its rights under this Agreement or delegate any of its duties or obligations
under this Agreement and any such attempted assignment or delegation shall be
null and void. This Agreement is not intended and shall not be construed to
obligate the Lender to take any action whatsoever with respect to the Collateral
or to incur expenses or perform or discharge any obligation, duty or disability
of the Borrower or GTA.

      11. Miscellaneous.

      (a) The provisions of this Agreement are intended to be severable. If any
provision of this Agreement shall for any reason be held invalid or
unenforceable in whole or in part in any jurisdiction, such provision shall, as
to such jurisdiction, be ineffective to the extent of such invalidity or
unenforceability without in any manner affecting the validity or enforceability
of such provision in any other jurisdiction or any other provision of this
Agreement in any jurisdiction.

      (b) No failure or delay on the part of the Lender in exercising any right,
remedy, power or privilege under this Agreement and the Note shall operate as a
waiver thereof or of any other right, remedy, power or privilege of the Lender
under this Agreement, the Note or any of the other Loan Documents; nor shall any
single or partial exercise of any such right, remedy, power or privilege
preclude any other right, remedy, power or privilege or further exercise thereof
or the exercise of any other right, remedy, power or privilege. The rights,
remedies, powers and privileges of the Lender under this Agreement, the Note and
the other Loan Documents are cumulative and not exclusive of any rights or
remedies which they may otherwise have.

                                       13
<PAGE>

      (c) All notices, statements, requests and demands given to or made upon
either party in accordance with the provisions of this Agreement shall be deemed
to have been given or made when personally delivered or when deposited in the
United States or Canadian mail, postage prepaid or with private overnight
courier service, charges prepaid, addressed as provided below, with a copy by
facsimile:

If to Borrower:

         Gran Tierra Energy Inc.
         Tenth Floor, 10 - 8th Avenue S.W.
         Calgary, Alberta, Canada T2P 1G5
         Attn: Dana Coffield, President and Chief Executive Officer
         Telephone: (403) 537-7454
         Facsimile: (403) 537-7440

with a copy to:

         McGuireWoods LLP
         1345 Avenue of the Americas
         New York, NY 10105
         Attn: Louis W. Zehil , Esq.
         Telephone: (212) 548-2138
         Facsimile: (212) 548-2175

If to Lender:

         Goldstrike Inc.
         1055 West Hastings Street, Suite 1980
         Vancouver, B.C. Canada V6E 2E9
         Attn: Dr. Ken Cai, President
         Telephone: (604) 688-8002
         Facsimile: (604) 688-8030

with a copy to:

         Gottbetter & Partners, LLP
         488 Madison Avenue, 12th Floor
         New York, NY 10022
         Attn: Adam S. Gottbetter, Esq.
         Telephone: (212) 400-6900
         Facsimile: (212) 400-6901

If to GTA

         [to come]

                                       14
<PAGE>

with a copy to:

         McGuireWoods LLP
         1345 Avenue of the Americas
         New York, NY 10105
         Attn: Louis W. Zehil , Esq.
         Telephone: (212) 548-2138
         Facsimile: (212) 548-2175

      (d) The section headings contained in this Agreement are for reference
purposes only and shall not control or affect its construction or interpretation
in any respect.

      (e) Unless the context otherwise requires, all terms used in this
Agreement which are defined by the Code shall have the meanings stated in the
Code.

      (f) The Code shall govern the settlement, perfection and the effect of
attachment and perfection of the Lender's security interest in the Collateral,
and the rights, duties and obligations of the Lender and the Borrower and GTA
with respect to the Collateral. This Agreement shall be deemed to be a contract
under the laws of the State of New York and the execution and delivery of this
Agreement and, to the extent not inconsistent with the preceding sentence, the
terms and provisions of this Agreement shall be governed by and construed in
accordance with the laws of that State.

      (g) This Agreement may be executed in several counterparts, each of which
shall be deemed an original but all of which shall constitute one and the same
instrument. All of such counterparts shall be read as though one, and they shall
have the same force and effect as though all the signers had signed a single
page.

                            [SIGNATURE PAGE FOLLOWS]

                                       15
<PAGE>

      IN WITNESS WHEREOF, and intending to be legally bound, the parties have
executed and delivered this Agreement as of the day and year set forth at the
beginning of this Agreement.

                                     BORROWER:

                                     GRAN TIERRA ENERGY INC.

                                     By:
                                        ------------------------------------
                                     Name:
                                     Title

                                     LENDER:

                                     GOLDSTRIKE INC.

                                     By:
                                        ------------------------------------
                                     Name:
                                     Title

                                     GRAN TIERRA ENERGY ARGENTINA S.A.

                                     By:
                                        ------------------------------------
                                     Name:
                                     Title

                                       16
<PAGE>

                                    EXHIBIT A

                Collateral Relating To Argentine Working Interest

All of GTA's rights, title and interest, including Proceeds thereof, in the
following:

Fourteen per cent (14%) of the participating interests in the Agreement for the
UTE: "YPF S.A. / Pluspetrol / Norcen, Palmar Largo Union Transitoria de
Empresas" entered into by and between Y.P.F. Sociedad Anonima, Pluspetrol
Sociedad Anonima, Norcen International Ltd, Compania General de Combustibles
Sociedad Anonima and Dong Won Co. Ltd, for the exploration, development and
exploitation of the Area "Palmar Largo", Northwest Basin, Salta and Formosa
Provinces, approved by Decree No. 2444/92 granted by the National Executive
Branch of Argentina, dated December 22nd, 1992, and published on December 24,
1992, in the Official Gazette.

                                       17

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