Amended and Restated Bridge Loan Promissory Note

$10,353,492                                                    September 1, 2005

      FOR VALUE RECEIVED, GRAN TIERRA ENERGY INC., an Alberta corporation
(hereinafter called the "Borrower"), hereby promises to pay to the order of
GOLDSTRIKE INC., a Nevada corporation (hereinafter called the "Lender"), c/o
Gottbetter & Partners LLP, 488 Madison Avenue, 12th Floor, New York, New York
10022, the principal sum of Ten Million Three Hundred Fifty Three Thousand Four
Hundred Ninety Two Dollars ($10,353,492) (the "Commitment"), or so much thereof
as shall have been borrowed by Borrower during the 120-day period following the
date of this Note as set forth on Schedule A attached hereto and made a part
hereof, in lawful money of the United States of America and in immediately
available funds.

      1. The outstanding principal balance of this Note, together with accrued
and unpaid interest thereon, shall be due and payable no later than the earlier
of (i) December 30, 2005 and (ii) the date of closing of the Merger, as
contemplated by the Term Sheet. The date such repayment is due is sometimes
referred to as the "Due Date." Upon the closing of the Merger, all indebtedness
evidenced hereby shall be deemed canceled and paid in full.

      2. This Note shall bear interest at the rate of nine percent (9%) per
annum on (i) for the period from September 1 through October 6, 2005, the sum of
Eight Million Three Hundred Thirty Seven Thousand Nine Hundred Sixteen Dollars
($8,337,916), (ii) for the period from October 7, 2005 through October 27, 2005,
the sum of Nine Million Three Hundred Fifty Three Thousand Four Hundred Ninety
Two Dollars ($9,353,492) and (iii) from and after October 28, 2005, the amount
of the entire Commitment, regardless of the actual amount borrowed by Borrower
hereunder as set forth on Schedule A hereto. Interest shall be calculated on the
basis of a year of three hundred sixty (360) days applied to the actual days on
which there exists an unpaid balance under this Note.

      3. Interest only shall be payable monthly in arrears, commencing thirty
(30) days from the date hereof. Thereafter, on the first business day of each
month through and including the month in which the Due Date occurs, Borrower
shall pay monthly installments of interest only.

      4. Upon an "Event of Default," as defined in the Bridge Loan Agreement
described below, the rate of interest accruing on the amount of the entire
Commitment of this Note shall increase to fifteen percent (15%) per annum. Such
default interest rate shall continue until all defaults are cured.

      5. This Note is subject to the terms of a Bridge Loan and Control Share
Pledge and Security Agreement (the "Bridge Loan Agreement") of even date
herewith by and between the Borrower and the Lender. This Note is secured by
collateral pledged by the Borrower and the Subsidiaries of the Borrower to the
Lender pursuant to a Security Agreement of even date herewith by and among the
Borrower, the Subsidiaries and the Lender (the "Security Agreement"), as well as
by the deposit into escrow of the Borrower Control Shares (as defined in the
Bridge Loan Agreement) pursuant to the terms of a Pledge and Escrow Agreement of
even date herewith by and among the Borrower, the Lender and Gottbetter &
Partners LLP, as escrow agent (the "Escrow Agreement"). All capitalized and
undefined terms herein shall have the meaning given them in the Bridge Loan
Agreement, the Security Agreement or the Escrow Agreement.

<PAGE>

      6. Upon the occurrence of an Event of Default under the Bridge Loan
Agreement or the Security Agreement, the entire principal amount outstanding
hereunder and all accrued interest hereon, together with all other sums due
hereunder, shall, as provided in the Bridge Loan Agreement, after the expiration
of the applicable Cure Period become immediately due and payable. If such Event
of Default is cured within the Cure Period, including but not limited to by
payment in full of the entire principal amount outstanding hereunder and all
accrued interest hereon, together with all other sums due hereunder, and
provided that the Lender has received repayment in full of the Purchase Price of
the Borrower Control Shares, then all indebtedness evidenced hereby shall be
deemed canceled and paid in full, and the Security Agreement and the liens
created thereby shall be terminated and of no further force and effect.

      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) of the Bridge Loan Agreement), the Borrower shall use
its best efforts to ensure that the Merger and the Transactions are consummated.

      7. This Note is secured by and is entitled to the benefits of the Security
Agreement. In addition to the rights and remedies given it by this Note and the
Security Agreement, the Lender shall have all those rights and remedies allowed
by applicable laws, including without limitation, the Uniform Commercial Code as
in effect in the State of New York. The rights and remedies of the Lender are
cumulative and recourse to one or more right or remedy shall not constitute a
waiver of the others. The Borrower shall be liable for all commercially
reasonable costs, expenses and attorneys' fees incurred by the Lender in
connection with the collection of the indebtedness evidenced by the Note.

      8. To the extent permitted by applicable law, the Borrower waives all
rights and benefits of any statute of limitations, moratorium, reinstatement,
marshalling, forbearance, valuation, stay, extension, redemption, appraisement
and exemption now provided or which may hereafter by provided by law, both as to
itself and as to all of its properties, real and personal, against the
enforcement and collection of the indebtedness evidenced hereby.

      9. All notices, requests, demands, and other communications with respect
hereto shall be in writing and shall be delivered by hand, sent prepaid by a
nationally-recognized overnight courier service or sent by the United States or
Canadian mail, certified, postage prepaid, return receipt requested, at the
addresses designated in the Bridge Loan Agreement or such other address as the
parties may designate to each other in writing.

      10. This Note or any provision hereof may be waived, changed, modified or
discharged only by agreement in writing signed by the Borrower and the Lender.
The Borrower may not assign or transfer its obligation hereunder without the
prior written consent of the Lender.

      11. The term "the Borrower" shall include each person and entity now or
hereafter liable hereunder, whether as maker, successor, assignee or endorsee,
each of whom shall be jointly, severally and primarily liable for all of the
obligations set forth herein.

      12. If any provision of this Note shall for any reason be held invalid or
unenforceable, such invalidity or unenforceability shall not affect any other
provision of this Note, but this Note shall be construed as if this Note had
never contained the invalid or unenforceable provision.

      13. This Note shall be governed by and construed in accordance with the
domestic laws of the State of New York, without giving effect to any choice of
law provision or rule. Any controversy or dispute arising out of or relating to
this Note shall be settled solely and exclusively in accordance with the
provisions of the Bridge Loan Agreement and the Security Agreement, dated as of
even date herewith, which provisions are incorporated by reference herein as
though fully set forth.
<PAGE>


      IN WITNESS WHEREOF, the undersigned Borrower has caused the due execution
of this Bridge Loan Promissory Note as of the day and year first herein above
written.


                                        GRAN TIERRA ENERGY INC.



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

<PAGE>

                                   SCHEDULE A

         This schedule sets forth the principal amount borrowed by Borrower from
the Lender, up to the maximum amount set forth on the face of this Note.


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                                                   Signature of Authorized
Date                    Principal Amount             Officer of Borrower
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September 1, 2005        $6,655,198.30
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October 7, 2005               $800,000
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November 1, 2005              $700,000
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