Exhibit 10.1

GUARANTY

This Guaranty (this “Guaranty”) dated as of April 2, 2013, is made by PENN
VIRGINIA CORPORATION, a Virginia corporation (“Guarantor”), in favor of MAGNUM
HUNTER RESOURCES CORPORATION, a Delaware corporation (“Seller”).

WITNESSETH:

WHEREAS, contemporaneously with the execution of this Guaranty, Guarantor,
Seller and Penn Virginia Oil & Gas Corporation, a Virginia corporation and
wholly-owned subsidiary of Guarantor (“Buyer”), are entering into that certain
Stock Purchase Agreement of even date herewith (as amended, modified or
otherwise supplemented from time to time, the “Agreement”); and

WHEREAS, Section 7.10 of the Agreement requires Guarantor to execute and deliver
this Guaranty to Seller, and Guarantor believes that it will obtain substantial
direct and indirect benefit from the rights obtained by it and by Buyer under
the Agreement; and

WHEREAS, in order to induce Seller to enter into the Agreement and to consummate
the transactions contemplated thereunder, and in consideration thereof,
Guarantor has agreed to execute this Guaranty.

NOW, THEREFORE, in consideration of the foregoing premises and for other good
and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, Guarantor hereby agrees as follows:

Article I

Guaranty

Section 1.1 Guaranty. Guarantor unconditionally, absolutely and irrevocably
guarantees and undertakes to Seller and any of its successors and assigns
(without duplication) the full and prompt performance and payment by Buyer of
all of the amounts to be paid, including without limitation under the
indemnification obligations of Buyer, and all agreements, covenants and other
obligations required to be performed, observed or satisfied by Buyer pursuant to
the terms of or under the Agreement and/or the documents required to be executed
and delivered by Buyer pursuant to the Agreement (collectively with the
Agreement, the “Transaction Documents”) and all other or additional obligations
of Buyer, or any increases, extensions and rearrangements of the foregoing
obligations, under any amendments, supplements and other modifications to the
Transaction Documents (collectively, the “Obligations”). Guarantor is liable as
a primary obligor. If any of the Obligations are not performed or paid in
accordance with the terms of the Transaction Documents, Guarantor shall within 2
Business Days after receipt of a notice from Seller regarding such nonpayment,
pay or perform or cause the payment or performance of the Obligations that are
required and performable. Guarantor may not rescind or revoke its obligations to
Seller under this Guaranty with respect to the Obligations. Guarantor shall make
any payment required hereunder to Seller in U.S. Dollars in immediately
available funds as directed by Seller.

--------------------------------------------------------------------------------

Section 1.2 Guaranty Absolute. This Guaranty shall be deemed accepted upon
receipt by Seller. Guarantor hereby guarantees that the Obligations will be
performed strictly in accordance with the terms of the Transaction Documents.
The Obligations constitute a present and continuing guaranty of payment and
performance, and not of collectability. Promptly upon Seller’s request,
Guarantor will deliver a reaffirmation of this Guaranty confirming its
obligations hereunder. The liability of Guarantor under this Agreement shall be
absolute, unconditional, present and continuing until all of the Obligations
have been indefeasibly paid in full or performed, as applicable, irrespective
of:

(a) any assignment or other transfer of the Transaction Documents or any of the
rights thereunder of Buyer therein;

(b) any amendment, supplement, waiver, renewal, extension or release of, or any
consent to or departure from or other action or inaction related to, the
Transaction Documents;

(c) any amendment, modification, increase, reduction, extension or rearrangement
of the Obligations;

(d) any acceptance by Seller of partial payment or performance from Buyer;

(e) any bankruptcy, insolvency, reorganization, arrangement, composition,
adjustment, dissolution, liquidation, or other like proceeding relating to
Buyer, or any action taken with respect to any of the Transaction Documents or
this Guaranty by any trustee or receiver, or by any court, in any such
proceeding;

(f) any absence of any notice to, or knowledge by, Guarantor, of the existence
or occurrence of any of the matters or events set forth in the foregoing
subsections (a) through (e);

(g) all notices and demands whether of presentment, protest, demand, grace,
dishonor or otherwise, other than any notices and demands expressly set forth
herein;

(h) any change in entity structure, existence or ownership of Buyer or
Guarantor; and

(i) any other circumstance that might otherwise constitute a defense available
to, or a discharge of, a guarantor.

Notwithstanding anything to the contrary set forth in this Guaranty and without
limiting Guarantor’s own defenses and rights hereunder, Guarantor reserves to
itself all rights, counterclaims and other defenses to which Buyer is or may be
entitled to arising from or out of the Transaction Documents, except for
defenses arising out of the bankruptcy, insolvency, dissolution or liquidation
of Buyer, the power or authority of Buyer to enter into the Transaction
Documents and to perform its obligations thereunder, and the lack of
enforceability of Buyer’s obligations under the Transaction Documents.

 

2

--------------------------------------------------------------------------------

Section 1.3 Subrogation Waiver. Guarantor agrees that it shall not have any
rights (direct or indirect) of subrogation, contribution, reimbursement or
indemnification or other rights of payment or recovery from Buyer for any
payments made by Guarantor hereunder until all Obligations have been paid and
performed, and Guarantor hereby irrevocably waives and releases any such rights
of subrogation, contribution and reimbursement or indemnification and other
rights of payment or recovery it may now have or hereafter acquire against Buyer
until all Obligations have been indefeasibly paid and performed.

Section 1.4 Continuing Guaranty. This Guaranty is a continuing guaranty and
shall (a) become effective immediately and remain in full force and effect until
the complete payment and performance of the Obligations, (b) be binding upon
Guarantor and its respective successors and assigns and (c) inure to the benefit
of and be enforceable by Seller and its respective successors, transferees and
assigns.

Section 1.5 Collection. The obligations of Guarantor hereunder are in no way
conditional or contingent upon any requirement on the part of Seller to first
attempt to enforce, request or require the payment of, or collect any of the
Obligations from or against Buyer or any other Person or to attempt to collect
any of the Obligations by any other means or give any notice of the occurrence
of a default under the Agreement (unless such notice is specifically required
under the Agreement) or any notice whatsoever to Guarantor or Buyer or any other
Person. Guarantor waives any rights under Chapter 43 of the Texas Civil Practice
and Remedies Code, Section 17.001 of the Texas Civil Practice and Remedies Code,
and Rule 31 of the Texas Rules of Civil Procedure or any other Law related to
the foregoing. Until all the Obligations have been irrevocably performed or paid
in full (and therefore the payment thereof is no longer subject to being set
aside or returned under any Law), Guarantor agrees not to take any action
pursuant to any rights which it may acquire against Buyer, or any other Person
liable for the performance or payment of the Obligations under this Guaranty,
including any right of subrogation (including any statutory rights of
subrogation under Section 509 of the Bankruptcy Code, 11 U.S.C. § 509, or under
any other Law), contribution, indemnification, reimbursement or exoneration or
any right to participate in any claim or remedy of Seller against Buyer or any
collateral which Seller now has or may acquire. If any amount shall be paid to
Guarantor in violation of the preceding sentence, such amount shall be held in
trust for the benefit of Seller and immediately turned over to Seller, with any
necessary endorsement, to be applied to the Obligations.

 

3

--------------------------------------------------------------------------------

Article II

Representations and Warranties

Section 2.1 Representations and Warranties. Guarantor represents and warrants to
Seller as follows:

(a) Guarantor is a corporation duly incorporated, validly existing and in good
standing under the laws of the Commonwealth of Virginia and has the requisite
corporate power to carry on its business as it is now being conducted;

(b) Guarantor has all requisite corporate power and authority to execute and
deliver this Guaranty and to perform its obligations hereunder, and the
execution, delivery and performance of this Guaranty and the transactions
contemplated hereby have been duly and validly authorized by all requisite
corporate action on the part of Guarantor;

(c) This Guaranty constitutes a valid and binding agreement of Guarantor,
enforceable against Guarantor in accordance with its terms, subject to
(i) applicable bankruptcy, insolvency, reorganization, moratorium and other
similar laws of general application with respect to creditors and (ii) general
principles of equity; and

(d) Neither the execution and delivery of this Guaranty nor the consummation of
the transactions and performance of the terms and conditions contemplated hereby
by Guarantor will (i) conflict with or result in a violation or breach of or
default under any provision of the articles of incorporation or bylaws of
Guarantor or any material agreement, indenture or other instrument under which
is bound, (ii) violate or conflict with any Law applicable to Guarantor or
(iii) require consent or approval of, filing with, or notice to any Person
which, if not obtained, would prevent Guarantor from performing its obligations
hereunder.

Article III

Miscellaneous

Section 3.1 No Waiver. No failure or delay on the part of Seller in exercising
any right, power or remedy under this Guaranty shall operate as a waiver thereof
nor shall any single or partial exercise thereof preclude any other or further
exercise thereof or the exercise of any other right, power or remedy.

Section 3.2 No Reduction. This Guaranty shall not be subject to any reduction,
limitation, modification, impairment or termination for any reason, including
any claim of waiver, release, surrender, alternation or compromise, and shall
not be subject to any defense or set-off, counterclaim, recoupment or
termination whatsoever, except as provided in Section 1.2.

Section 3.3 Enforcement. Notwithstanding anything to the contrary, Seller may
proceed to enforce this Guaranty against Guarantor without first pursuing or
exhausting any right or remedy that Seller or any of its successors and assigns
may have against Buyer or any other Person.

 

4

--------------------------------------------------------------------------------

Section 3.4 Reinstatement. Notwithstanding anything in this Guaranty to the
contrary, this Guaranty shall continue to be effective or be reinstated, as the
case may be, if at any time any payment of any portion of the Obligations is
revoked, terminated, rescinded or reduced or must otherwise be restored or
returned upon the insolvency, bankruptcy or reorganization of Guarantor or any
other Person or otherwise, as if such payment had not been made and whether or
not Seller is in possession of or has released this Guaranty and regardless of
any prior revocation, rescission, termination or reduction.

Section 3.5 Amendment. This Guaranty may not be amended or modified except by an
instrument in writing signed by or on behalf of Guarantor and Seller.

Section 3.6 Notices. All notices required or permitted hereunder shall be in
writing and deemed sufficiently given for all purposes hereof if (a) delivered
in person, by courier or by registered or certified United States Mail to the
Person to be notified, with receipt obtained, or (b) sent by telecopy, telefax
or other facsimile or electronic transmission, with “answer back” or other
“advice of receipt” obtained, in each case to the appropriate address or number
as set forth below. Each notice shall be deemed effective on receipt by the
addressee as aforesaid; provided that, notice received by telex, telecopy,
telefax or other facsimile or electronic transmission after 5:00 p.m. at the
location of the addressee of such notice shall be deemed received on the first
Business Day following the date of such electronic receipt. Notices shall be
addressed as follows:

 

If to Seller:    Magnum Hunter Resources Corporation    777 Post Oak Boulevard,
Suite 650    Houston, Texas 77056    Attention: General Counsel    Facsimile:
(832) 369-6992 With a copy to (which shall not constitute notice to Seller):   
Fulbright & Jaworski L.L.P.    1301 McKinney Street, Suite 5100    Houston,
Texas 77010    Attention: Craig S. Vogelsang    Facsimile: (713) 651-5246   
cvogelsang@fulbright.com If to Guarantor:    Penn Virginia Corporation    Four
Radnor Corporate Center Suite 200    100 Matsonford Road    Radnor, Pennsylvania
19087    Attention: Nancy M. Snyder    Facsimile: (61) 687-3688   
nancy.snyder@pennvirginia.com

 

5

--------------------------------------------------------------------------------

With a copy to (which shall not constitute notice to Guarantor):    Vinson &
Elkins L.L.P.    666 Fifth Avenue    New York, New York 10103    Attention:
Michael J. Swidler    Facsimile: (917) 849-5367    mswidler@velaw.com    and   
Vinson & Elkins L.L.P.    1001 Fannin Street, Suite 2500    Houston, Texas 77002
   Attention: Gillian A. Hobson    Facsimile: (713) 615-5794   
ghobson@velaw.com

Either party may change its address for notice by notice to the other in the
manner set forth above.

Section 3.7 Applicable Law. THIS GUARANTY AND THE LEGAL RELATIONS BETWEEN
GUARANTOR AND SELLER SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE
LAWS OF THE STATE OF TEXAS WITHOUT REGARD TO PRINCIPLES OF CONFLICTS OF LAWS
OTHERWISE APPLICABLE TO SUCH DETERMINATIONS.

Section 3.8 Severability. If any term or other provisions of this Guaranty is
held invalid, illegal or incapable of being enforced under any rule of law, all
other conditions and provisions of this Guaranty shall nevertheless remain in
full force and effect so long as the economic or legal substance of the
transactions contemplated hereby is not affected in a materially adverse manner
with respect to Guarantor or Seller; provided, however, that if any such term or
provision may be made enforceable by limitation thereof, then such term or
provision shall be deemed to be so limited and shall be enforceable to the
maximum extent permitted by applicable Law.

Section 3.9 Entire Agreement. This Guaranty, the Confidentiality Agreement, the
Transaction Documents and the Appendix, Exhibits and Schedules attached to the
Agreement, constitute the entire agreement between the parties pertaining to the
subject matter hereof, and supersede all prior agreements, understandings,
negotiations and discussions, whether oral or written, of the parties pertaining
to the subject matter hereof.

 

6

--------------------------------------------------------------------------------

Section 3.10 Headings. Article and Section headings used herein are for
convenience only and shall not constitute part of this Guaranty and shall be
disregarded in construing the language contained in this Guaranty.

Section 3.11 Assignment. This Guaranty shall not be assigned by any party hereto
(including by operation of law or otherwise), except in connection with an
assignment permitted under the Agreement. Any purported assignment of this
Guaranty in violation of this Section 3.11 shall be null and void.

Section 3.12 Defined Terms. Capitalized terms used herein without definition
shall have the meanings given to such terms in the Agreement.

Section 3.13 Dispute Resolution. If a dispute or difference between Guarantor
and Seller arises under or out of, in relation to or is in any way connected
with this Guaranty, Guarantor and Seller shall resolve such dispute or
difference by following the procedures set forth in Section 14.3 of the
Agreement (except that (a) Guarantor shall be substituted for Buyer and
(b) Guaranty shall be substituted for Agreement for all purposes thereunder).

Section 3.14 Affiliate Liability. Each of the following is herein referred to,
for purposes of this Section 13.14, as a “Guarantor Affiliate”: (a) any direct
or indirect holder of equity interests or any other form of ownership in
Guarantor (whether limited or general partners, members, shareholders or
otherwise); and (b) any director, officer, manager, employee, representative or
agent of (i) Guarantor or (ii) any Affiliate of Guarantor. No Guarantor
Affiliate shall have any liability or obligation of any nature whatsoever in
connection with or under this Guaranty, or the transactions contemplated hereby,
and Seller hereby waives and releases all claims of any such liability and
obligation.

Section 3.15 Interpretation. This Guaranty is the result of arm’s-length
negotiations from equal bargaining positions. In the event an ambiguity or
question of intent or interpretation arises, this Guaranty shall be construed as
if drafted jointly by the parties and no presumption or burden of proof shall
arise favoring or disfavoring any party by virtue of the authorship of any of
the provisions of this Guaranty. The captions in this Guaranty have been
inserted for convenience only and shall be given no substantive meaning or
significance whatever in construing the terms and provisions of this Guaranty.

[Remainder of Page Intentionally Left Blank—Signature Page Follows]

 

7

--------------------------------------------------------------------------------

IN WITNESS WHEREOF, this Guaranty is executed by Guarantor as of the date first
written above.

 

GUARANTOR: PENN VIRGINIA CORPORATION By:   /s/ Nancy M. Snyder Name:   Nancy M.
Snyder Title:   Executive Vice President  

and General Counsel

[SIGNATURE PAGE TO GUARANTY]