Document zd1VBb0bD6MD0gGkX7126EMeR

REPORT OF VISUAL INSPECTION September 10, 2024 By TOEROEK ASSOCIATES, INC. and TETRA TECH INC. For U.S. ENVIRONMENTAL PROTECTION AGENCY Region 10 Land Enforcement Section At the request of U.S. Environmental Protection Agency (EPA) Region 10, Toeroek Associates, Inc. and its subcontractor Tetra Tech Inc. (Toeroek team) conducted a visual inspection of a drum storage area on property owned by the Ukpeavik Iupiat Corporation (UIC) at approximately 71.327935 N, 156.676437 W. Aerial photographs showing the area are Appendix A. The 24 photographs I took during my visual inspection are included in Appendix B. As directed by EPA Region 10 representatives, I conducted a visual inspection of an area on the UIC property adjacent to Iisavik College where 55-gallon (drum) and 300-gallon (tote) containers had been observed. Associated with this site visit, I reviewed documentation on RCRAInfo to determine if the property had been assigned an EPA ID number. I found an EPA ID number that appeared to be associated with the UIC property and the containers. EPA ID AKR000210807 was initially assigned on September 12, 2024, with the status of a large quantity generator and the name NARL 5 (Building 5 of the Naval Arctic Research Laboratory site). This site was described as being the location for "waste storage (advised by EPA) as waste (POL1, natural and refined constituents) deemed hazardous from analytical results." The Notification also states that the waste was generated during the Avak Creek release. The RCRA Site Detail report is in Appendix C. On May 21, 2024, unknown petroleum material was identified on a tundra lake that drains into Avak Creek approximately 20 miles outside of Utqivik. Alaska Department of Environmental Conservation (ADEC) notified the National Response Center on June 5, 2024. UIC has been managing the response as the landowner and, at the time of the initial response, the potentially responsible party. UIC deployed absorbent and hard booms on the lake to try and prevent the petroleum material from reaching Avak Creek. Based on fingerprint analysis of a sample collected and analyzed by the U.S. Geological Survey (USGS), the USGS concluded that the petroleum material was from a naturally occurring seep. More information about the release is in the USGS report in Appendix D. The waste characterization sampling was not described in the USGS report. When I arrived, I observed an approximately 15,000-square-foot area surrounded by a 6-foot-high chain link fence (Photograph 2). The entry to the fenced area did not have a gate, and the area did not have any signage. I took photographs primarily from the right-of-way. Because the area appeared to be unsecured and did not have any posted prohibitions or contact information, I briefly entered the fenced area to photograph labels on containers. 1 that is, petroleum, oils, and lubricants Page 1 of 2 Inside the fenced area, I observed approximately 100 drums, five totes, 20 transformers, 20 1-cubic-yard textile bags (super sacks), and five shipping containers. The horizontal tanks inside the fence were labeled for "LP" (the common abbreviation for "liquid propane"), but their contents or fill level was not determined. Most of the drums and all of the totes were labeled as "hazardous waste." They were identified as characteristically toxic arsenic-containing hazardous waste and dated in June 2024 (Photographs 21 through 24). A label on one of the totes suggested that the waste determination was based on analysis ("this container on hold pending analysis") (Photograph 24). Contact information was also provided on these containers (Ross Wilhelm of UIC, 907-852-7448). The containers described above were also labeled to indicate that they were related to the Avak Creek Release. As described above, the location of the release was approximately 20 miles from the location where the containers were held. Based on these facts, the UIC drum location was not the generator site, even though the determination that the waste was hazardous may have been made after the containers were brought to the NARL 5 location. Because this waste was not generated onsite, this site appears to be storing hazardous waste without a permit, in violation of RCRA Section 3005. In addition to the containers of waste related to the Avak Creek release, I observed approximately 50 other containers with either no labels or incomplete labels. I observed one container that was labeled as "used solvent" and dated August 9, 2017 (Photograph 10). Digitally signed by Heather Wood Date: 2025.01.28 _______________16_:5_0:_43_-_06_'0_0'_____________ Heather K. Wood, Inspector Tetra Tech, Inc. Appendices Appendix A - Aerial Photographs With Facility Location (2 Pages) Appendix B - Photolog (14 Pages, 24 Photos) Appendix C - RCRA Site Detail Report (3 Pages) Appendix D - Avak Creek Oil Occurrence, Alaska, Summary Report (23 Pages) Page 2 of 2 UIC Drum Storage July 23, 2016 imagery Legend Iisavik College UIC Drum Storage Image 2024 Maxar Technologies Appendix A Image 2024 Maxar Technologies N 1000 ft Page 1 of 2 UIC Drum Storage July 23, 2016 imagery Image 2024 Maxar Technologies Appendix A Image 2024 Maxar Technologies 300 ft N Page 2 of 2 UIC Drum Storage Utqiavik, North Slope Borough, Alaska PHOTO LOG Site Name / City: NARL 5 5 NARL Utqivik, Alaska 99723 Site ID #: AKR000210807 Photographer: Heather K. Wood Type of Camera: Samsung A53 5G UW, Serial # R5CT325KKDT Digital Recording Media: SD memory card All digital photos were copied by: Heather Wood All digital photos were copied to: Personal laptop computer Original copy is stored in: Tetra Tech, Inc.'s OneDrive cloud server. No changes were made in the original image files prior to storage on the server. Pic# Photographer 1 Heather Wood 2 Heather Wood 3 Heather Wood 4 Heather Wood 5 Heather Wood 6 Heather Wood 7 Heather Wood 8 Heather Wood 9 Heather Wood 10 Heather Wood 11 Heather Wood 12 Heather Wood 13 Heather Wood 14 Heather Wood 15 Heather Wood 16 Heather Wood 17 Heather Wood 18 Heather Wood 19 Heather Wood 20 Heather Wood 21 Heather Wood 22 Heather Wood 23 Heather Wood 24 Heather Wood Date 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 9/10/24 Time 12:47 12:48 12:48 12:48 12:48 12:48 12:48 12:48 12:48 12:48 12:48 12:49 12:49 12:49 12:49 12:49 12:49 12:49 12:50 12:50 12:50 12:50 12:51 12:51 File Name 20240910_124724.jpg 20240910_124801.jpg 20240910_124808.jpg 20240910_124814.jpg 20240910_124821.jpg 20240910_124828.jpg 20240910_124834.jpg 20240910_124839.jpg 20240910_124843.jpg 20240910_124852.jpg 20240910_124854.jpg 20240910_124904.jpg 20240910_124913.jpg 20240910_124916.jpg 20240910_124926.jpg 20240910_124941.jpg 20240910_124953.jpg 20240910_124957.jpg 20240910_125004.jpg 20240910_125018.jpg 20240910_125048.jpg 20240910_125058.jpg 20240910_125109.jpg 20240910_125122.jpg Appendix B Page 1 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska Description Photographer This photograph shows the UIC Drum Storage area on the UIC property, adjacent to Iisavik College. Heather K. Wood EPA ID n/a Direction N 1 Date: 9/10/24 Time: 12:47 Description Photographer This photograph shows 10 55-gallon containers (drums) and eight open drums filled with sand and concrete just outside the fenced area. The fence was not gated. Heather K. Wood EPA ID n/a Direction SE 2 Date: 9/10/24 Time: 12:48 Appendix B Page 2 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska Description Photographer This photograph shows the area inside the fence, which held approximately 100 drums, 20 transformers, five 300-gallon containers (totes), 20 1-cubic-yard textile bags (super sacks), and five shipping containers. The horizontal tanks inside the fence were labeled for "LP" (liquid propane), but their contents or fill level was not determined. Drums in the foreground were labeled as hazardous waste (arrows). Heather K. Wood EPA ID n/a Direction NE 3 Date: 9/10/24 Time: 12:48 Description Photographer This photograph shows another view of the containers in the fenced area. Heather K. Wood EPA ID n/a Direction NE 4 Date: 9/10/24 Time: 12:48 Appendix B Page 3 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska Description Photographer This photograph shows another view of the containers outside the fenced area, shown in Photograph 2. Heather K. Wood EPA ID n/a Direction SE 5 Date: 9/10/24 Time: 12:48 Description Photographer This photograph shows another view of the containers outside the fenced area, shown in Photograph 2. Heather K. Wood EPA ID n/a Direction N 6 Date: 9/10/24 Time: 12:48 Appendix B Page 4 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska Description Photographer This photograph shows another view of the containers outside the fenced area, shown in Photograph 2. Heather K. Wood EPA ID n/a Direction NW 7 Date: 9/10/24 Time: 12:48 Description Photographer This photograph shows another view of the containers inside the fenced area, shown in Photograph 3. Heather K. Wood EPA ID n/a Direction NW 8 Date: 9/10/24 Time: 12:48 Appendix B Page 5 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska Description Photographer This photograph shows another view of the containers inside the fenced area, shown in Photograph 3. A "hazardous waste" label is visible on one of the totes (arrow). Heather K. Wood EPA ID n/a Direction NW 9 Date: 9/10/24 Time: 12:48 Description Photographer This photograph shows another view of the containers inside the fenced area, shown in Photograph 3. A "hazardous waste" label is visible on one of the drums (arrow). A drum in the foreground is labeled as "used solvent" and dated August 9, 2017 (inset). Heather K. Wood EPA ID n/a Direction NW 10 Date: 9/10/24 Time: 12:48 Appendix B Page 6 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska Description Photographer This photograph shows another view of the containers inside the fenced area, shown in Photograph 3. Heather K. Wood EPA ID n/a Direction NW 11 Date: 9/10/24 Time: 12:48 Description Photographer This photograph shows another view of the containers inside the fenced area, shown in Photograph 3. Heather K. Wood EPA ID n/a Direction NW 12 Date: 9/10/24 Time: 12:49 Appendix B Page 7 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska Description Photographer This photograph shows approximately 30 drums on pallets, with yellow "hazardous waste" labels. Heather K. Wood EPA ID n/a Direction N 13 Date: 9/10/24 Time: 12:49 Description Photographer This photograph shows another view of the containers shown in Photograph 13. Heather K. Wood EPA ID n/a Direction NW 14 Date: 9/10/24 Time: 12:49 Appendix B Page 8 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska Description Photographer This photograph shows another view of the containers shown in Photograph 13. Heather K. Wood EPA ID n/a Direction NW 15 Date: 9/10/24 Time: 12:49 Description Photographer This photograph shows another view of the containers shown in Photograph 13. Heather K. Wood EPA ID n/a Direction W 16 Date: 9/10/24 Time: 12:49 Appendix B Page 9 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska Description Photographer This photograph shows another view of the containers shown in Photograph 13. Heather K. Wood EPA ID n/a Direction W 17 Date: 9/10/24 Time: 12:49 Description Photographer This photograph shows the approximately 30 transformers inside the fenced area. Heather K. Wood EPA ID n/a Direction N 18 Date: 9/10/24 Time: 12:49 Appendix B Page 10 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska Description Photographer This photograph shows another view of the transformers shown in Photograph 18. The super sacks are visible in the background, next to the shipping container. Heather K. Wood EPA ID n/a Direction N 19 Date: 9/10/24 Time: 12:50 Description Photographer This photograph shows overpack and salvage drums and some of the transformers visible in Photograph 18. Heather K. Wood EPA ID n/a Direction N 20 Date: 9/10/24 Time: 12:50 Appendix B Page 11 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska Description Photographer This photograph shows the label on one of the drums in Photograph 13, identifying the waste as arsenic-containing (D004) mixed petroleum- water hazardous waste. It is dated June 7, 2024, and is identified as coming from Avak Creek. The inset shows the label. Heather K. Wood EPA ID n/a Direction NW 21 Date: 9/10/24 Time: 12:50 Description Photographer This photograph shows the label on one of the drums in Photograph 13, identifying the waste as arsenic-containing (D004) mixed petroleum- water hazardous waste. It is dated June 4, 2024, and is identified as coming from Avak Creek. Heather K. Wood EPA ID n/a Direction NW 22 Date: 9/10/24 Time: 12:50 Appendix B Page 12 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska Description Photographer This photograph shows the label on one of the drums in Photograph 13, identifying the waste as arsenic- containing (D004) mixed petroleum-water hazardous waste. It is dated June 4, 2024, and is identified as coming from Avak Creek. The drum is labeled as container #40 (or 46). Drums in the background are also labeled as related to the Avak release and also dated June 4, 2024. The yellow drum at right is labeled as water and oil, and appears to be dated May 2024. Heather K. Wood EPA ID n/a Direction NW 23 Date: 9/10/24 Time: 12:51 Appendix B Page 13 of 14 UIC Drum Storage Utqiavik, North Slope Borough, Alaska This photograph shows the label on the tote identified in Photograph 9, Description identifying the waste as arsenic-containing (D004) mixed petroleum-water hazardous waste. It is undated and is identified as coming from "Avak Release." The inset shows the labels. The tote is labeled as container #45. Photographer Heather K. Wood EPA ID n/a Direction NW 24 Date: 9/10/24 Time: 12:51 Appendix B Page 14 of 14 RCRA Site Detail Report run on: January 13, 2025 4:48:12 PM EST User Selection Criteria Handler ID: History: BR Cycles: Notes: AKR000210807 All records Show all Yes Version 6.0 Report Description This report provides "all available details" from the Handler module and summarized information from the Waste Activity Monitoring module for the specified RCRA site. Details reported include basic site identification information; handler universe information; source record information including location and mailing address, contact person and address, NAICs, and regulated waste activities. For Biennial Report source records on or after the 2001 BR cycle, additional information reported includes quantity totals (generated, managed, shipped, received), and the top ten GM forms by quantity generated. Information reported for the RCRA site may be limited by latest historical information and most recent Biennial Report cycle. The data is sorted by the most recent Received Date. Note: Some data is suppressed if it is null or blank. See the Reports Library documentation in RCRAInfo Help for additional details. Appendix C Last Updated On: 05/08/2024 Page 1 of 3 RCRA Site Detail Report run on: January 13, 2025 4:48:12 PM EST *** WARNING *** Sensitive information may be displayed on this report. *** WARNING *** NARL 5 EPA Region: 10 Extract: Y County: NORTH SLOPE State District: Page 2 AKR000210807 Universes: Federal Generator: State Generator: Short Term Generator: Subpart K/College: Large Qty Hndlr of UW: LQG F Y N N Transporter: N Importer: N Mixed Waste Generator: N Subpart K/Hospital: N Subpart P: N Operating TSDF: ------ Commercial TSDF: N HSM: N Subpart K/Non-profit: N Active Flag: EI Indicator (HE / GW): IC In Place: Subpart K/Withdrawal: Y N / N N N Receive Date: 09/12/2024 Source: Notification Seq.: 1 Location Address 5 NARL UTQIAGVIK, AK 99723 UNITED STATES Latitude: 71.328 Longitude: -156.677 Mailing Address PO BOX 890 UTQIAGVIK, AK 99723 UNITED STATES Contact Person For Source Information ROSS WILHELM VP OF ARCTIC OPERATIONS AND DEVELOPMENT Phone: 907-852-7448 ROSS.WILHELM@UICCS.COM Preferred Language: ENGLISH 1250 AGVIK STREET UTQIAGVIK, AK 99723 UNITED STATES Owner (current) UKPEAVIK IUPIAT CORPORATION As of: 06/28/2024 Operator (current) UIC REAL ESTATE, LLC As of: 06/28/2024 PO BOX 890 BARROW, AK 99723 UNITED STATES PO BOX 890 BARROW, AK 99723 UNITED STATES Type: Private Phone: 907-852-4460 Type: Private Land Type: Private Non Notifier: No TSD Date: Accessibility: NAICS Codes: 551112 OFFICES OF OTHER HOLDING COMPANIES Notes Short Term Generator: Waste was generated as part of the initial AVAK Creek spill response conducted by UIC. The site has been designated as a natural seep. Additional waste generated by UIC is not anticipated for this site. Public: Please direct questions on any portion of this application to Jeffrey Schulz (UMIAQ Environmental) Jeffrey.Schulz@uiccs.com 907.360.9291. Site Address: Naval Arctic Research Laboratory (NARL) (Building) 5. Parcel ID R-001-201-08 Listed site location is for current waste storage (advised by EPA) as waste (POL, natural and refined constituents) deemed hazardous from analytical results. The source of the waste has been deemed a natural seep (EPA). Additional cleanup by UIC is not anticipated. Waste generated as part of the Tundra Lake, Avak Creek Discharge Site initial spill response activities conducted by UIC. https://response.epa.gov/site/site_profile.aspx?site_id=16511 Internal **(Grasso 9-12-24) Assigning new RCRA ID for short term clean up.** Regulated Waste Activities Hazardous Waste Federal: Large Quantity Generator State: AK-F Same as Federal Short Term Generator: Yes Recycler (stores prior to recycling): No Mixed Waste Generator: N/A Recycler (no storage prior to recycling): No TSD Activity: No Small Quality On-site Burner Exemption: No Off-Site Receipt: No Smelting, Melting, Refining Furnace Exemption: No Description of Hazardous Wastes (as reported on Site Identification Form) EPA Waste Codes: D004 Additional Regulated Waste Activities Other Waste Activites Transporter: No Transfer Facility: No Underground Injection Control: No Importer Activity: No Recognized Trader - Importer: No Recognized Trader - Exporter: No Spent Lead Acid Battery - Importer: No Spent Lead Acid Battery - Exporter: No Appendix C Quick report Page 2 of 3 RCRA Site Detail Report run on: January 13, 2025 4:48:12 PM EST *** WARNING *** Sensitive information may be displayed on this report. *** WARNING *** Universal Waste Activities Destination Facility for Universal Waste: No Used Oil Activities Transporter: Transfer Facility: Processor: Refiner: Off-Specification Used Oil Burner: No Marketer who directs shipment off-specification used No oil to off-specification used oil burner: No Marketer who first claims the used oil meets the No specifications: No Page 3 No No *** End of Report *** Appendix C Quick report Page 3 of 3 Avak Creek Oil Occurrence, Alaska Summary Report Submitted to U.S. Environmental Protection Agency & Alaska Department of Environmental Conservation Submitted by U.S. Geological Survey Alaska Petroleum Systems Project Palma Botterell, Research Petroleum Geochemist pbotterell@usgs.gov Dave Houseknecht, Supervisory Research Geologist dhouse@usgs.gov Mike Moldowan, CEO of Biomarker Technologies, Inc. jmmoldowan@biomarker-inc.com October 28, 2024 Appendix D Page 1 of 23 Summary Geochemical analyses of the Avak Creek oil samples reveal they are geochemically consistent with seeps on Cape Simpson (25 to 40 miles east of Avak Creek), several exploration-well tests, and many produced crude oils across the North Slope. The inferred source rock from which most of the oil was generated is interpreted to be the Lower Cretaceous Hue-GRZ, mostly Aptian to Albian in age (~126-110 Ma), in the early stages of oil generation. There does not appear to be any significant geochemical difference between shoreline and tundra samples, suggesting a single source for the Avak Creek oil occurrence. Further, the geochemical signatures of the Avak Creek oil samples are generally not consistent with processed oils, refinery waste products, or synthetic products. Results of biomarker acids analyses reveal that anaerobic biodegradation occurred in the subsurface, suggesting that the Avak Creek oils, or at least some portion of them, emanated as natural seeps that leaked/migrated from underground reservoirs, as opposed to a crude oil spill. Introduction In July 2024, A rapidly developing petroleum environmental issue emerged involving an "unknown release" of oil in a lake and tundra near Avak Creek on Native lands near Utqiagvik (formerly Barrow), the administrative center for the North Slope Borough. The U.S. Environmental Protection Agency (USEPA) and Alaska Department of Environmental Conservation (ADEC) contacted the U.S. Geological Survey (USGS) to determine whether this newly discovered oil occurrence is a previously undocumented, natural oil seep or some type of contamination (e.g., recent unsuccessful plugging of a 49-year-old exploration well, crude oil spill, refinery waste product, etc.). Existing preliminary data from the U.S. Coast Guard Marine Safety Lab was inconclusive in determining the likely origin of the oil. Avak Creek samples (Fig. 1) were provided by the USEPA and ADEC for further geochemical analyses. Funding for these analyses was provided mainly from the USGS Energy Resources Program. Dave Houseknecht investigated the regional and local geologic framework. Palma Botterell characterized the oil geochemistry, in comparison to local Cape Simpson area seeps and to other previously characterized oils across the North Slope. The geological framework of the Avak Creek site was constructed using seismic and well data, plus basin modeling results, to identify local petroleum source rocks; map the structural geometry and faults; identify areas where source rocks are immature, mature, and overmature; and infer likely oil-migration pathways into the area. Geochemical interpretations of the likely origin of the newly discovered oil occurrence were made by integrating both subsurface data (seismic surveys and exploration well penetrations) and geochemical data from local and regional oil seeps, exploration well tests, and produced oils across the North Slope, Alaska (Fig. 2). Analytical work and interpretations were done primarily in collaboration with Mike Moldowan (CEO, Biomarker Technologies, Inc., BTI), with additional laboratory support from Jody Wycech (Project Chief of the USGS Petroleum Geochemistry Research Lab, PGRL) and Paul Lillis (USGS, emeritus). Appendix D Page 2 of 23 Geologic Framework Northernmost Alaska includes a unique, high standing subsurface feature known as the "Barrow High" (Fig. 3). The Barrow High represents the eastern portion of the broader Arctic Platform (Connors and Houseknecht, 2022, their Figure 3), a high standing area of preMississippian basement rocks that extends more than 150 miles west from Point Barrow beneath the western Beaufort Sea and northeastern Chukchi Sea. Basement rocks of the Arctic Platform stand hundreds to thousands of feet higher than surrounding basement rocks beneath the Alaska North Slope to the south and east, the Chukchi Sea shelf to the west, and the Canada Basin offshore to the north. Younger sedimentary deposits in these surrounding basins range from Mississippian (MISS in Fig. 6) to Miocene in age. Through hundreds of million years, as sediments accumulated over the Barrow High and Arctic Platform, those younger strata thin onto - and many pinch out completely - as they were deposited higher onto the Barrow High and into shallower water of the high standing region. Manifestation of these strata thinning and pinching out onto the southern flank of the Barrow High are shown in Figures 4 and 5. The stratigraphy of the younger rocks is shown in Figure 6A, which shows the stratigraphy typically present across most of the Alaska North Slope. However, in the Barrow High many of these strata are absent either because they were never deposited or because they were later eroded (Fig. 6B). Thus, the Iko Bay #1 exploration well, drilled by the U.S. Navy in 1975 and just one mile east of the Avak Creek oil occurrence, penetrated only a fraction of the strata present across most of the North Slope before entering basement rocks at a depth of 2,705 ft. Rocks penetrated by the Iko Bay #1 are shown as yellow vertical lines in Figure 6B. As a result of this depositional pattern, all Mississippian and younger strata thicken progressively southward beneath the North Slope and northward into the Canada Basin. A consequence of this basinward thickening is that each formation was buried deeper farther into the basins and, thus, heated to higher temperatures farther from the Barrow High - Arctic Platform. The increase in maximum temperature is expressed as higher "thermal maturity," a measure of the maximum temperature to which a formation was exposed. In petroleum source rocks, the thermal maturity, in turn, controls the stage of petroleum generation that has occurred. Figure 7 is a map of Arctic Alaska from the Brooks Range on the south to the central Canada Basin on the north, and from the Chukchi Sea on the west to Canada on the east. The colored contours represent the level of thermal maturity of the base of the Brookian tectonostratigraphic sequence, including strata of petroleum source rock S3b (Fig. 6). In the area of shallowest burial on the Barrow High, as well as areas to the west and east, the thermal maturity at the base of the Brookian sequence is less than 0.7% thermal maturity (scale is percent vitrinite reflectance, % VR), or the area that is mainly blue in Figure 7, which indicates the "Early Mature" oil window. This signifies that oil generation was in early stages of development when source rock S3b was at maximum temperature, which occurred during the Late Cretaceous. To the south, source rock S3b was buried deeper and heated to higher temperature, and the modeled thermal maturity lies between 0.7 and 1.0% VR (green part of map). This indicates a "Mid Mature" stage of oil Appendix D Page 3 of 23 generation during the Late Cretaceous. Still farther south, source rock S3b was buried deeper and heated to higher temperature, and the modeled thermal maturity lies between 1.0 and 1.3% VR, indicating a "Late Mature" stage of oil generation. The areas of "Mid Mature" and "Late Mature" represent stages of maximum oil generation from source rocks. Still farther south, source rock S3b lies at modeled thermal maturity values higher than 1.3% VR, which is considered the Main Gas Generation Window. In this stage, any oil remaining in the pink area of the map will have been cracked to natural gas. Moreover, natural gas may be generated directly from any remaining kerogen in the source rock. Inasmuch as any source rocks in strata older than S3b will have been buried deeper and heated to higher temperature than S3b, those older source rocks will have passed through the stages of oil and gas generation described above earlier than S3b. Finally, the inset map in the upper right of Figure 7 is a magnified view of the area near Avak Creek, which is indicated by the red star. The three exploration wells indicated by red diamonds, the South Meade, Kuyanak, and West Dease wells, are the most pertinent to interpreting the petroleum generation history of the Avak Creek area and those will be considered in the next section. Local Geology of the Avak Creek Area The local geology of the Avak Creek area is known from numerous petroleum exploration wells and natural gas development wells drilled since the late 1940s, and from two-dimensional (2-D) seismic data collected since the 1950s (Fig. 8). One seismic line is particularly important - a south-north line collected by the U.S. Navy in 1978; the northern part of this seismic line directly crosses the Avak Creek oil occurrence and nearly crosses the Iko Bay #1 exploration well (Fig. 8). An image of the seismic line highlighted in Figure 8 is shown in Figure 9. Strata correlated into this seismic line from surrounding areas and confirmed by the strata penetrated by the Iko Bay #1 well are shown in the legend and as labels in the figure; those range from the top of basement rocks (at bottom) to the Lower Cretaceous Nanushuk Formation (at top; Fig. 9). The seismic image clearly shows that south of Avak Creek, the top of basement and overlying strata dip (tilt) to the south, forming a homocline (geological term for strata that display a uniform dip in one direction). Directly beneath Avak Creek, a north-dipping normal fault is present, and that fault is accompanied by two south-dipping, subsidiary normal faults. Farther north, near the end of the seismic line, a second north-dipping normal fault is present. All these normal faults display relatively minor offset (tens to a few hundred feet); nevertheless, the faults clearly offset the strata and result in dip reversal on a local scale. Directly beneath Avak Creek, strata are folded into a gentle arch (anticline), the northern flank of which is accommodated by the north-dipping normal fault with the two south-dipping subsidiary normal faults. Two intersecting seismic lines, a short northwest-southeast line and a longer northwest-southeast line (Fig. 8) confirm that the subtle anticline beneath Avak Creek also displays subtle anticlinal closure in that orientation. Thus, the anticline beneath Avak Creek has subtle, four-way closure. Between the two north-dipping normal faults (Fig. 9), the top of basement and overlying strata display a sag (syncline) in which the Iko Bay 1 well was drilled. Appendix D Page 4 of 23 Strata present above basement include several distinctive units labeled as horizons in the legend below the seismic image in Figure 9. Among these are two petroleum source rocks, the Triassic Shublik Formation (labeled S1 here and in Fig. 6) and the Lower Cretaceous pebble shale unit and gamma-ray zone (PSU and GRZ, respectively, and together labeled S3b here and in Fig. 6). Whereas it is common for the older Shublik Formation (S1 in Fig. 6) to expel oil that migrates through deeper strata, it is common for the younger PSU and GRZ (S3b in Fig. 6) to expel oil that migrates through inclined "clinoform" strata, which downlap directly onto the source rocks. Moreover, those strata display origin dip, reflecting their deposition on marine slopes, which merges at shallower depth the overlying Nanushuk Formation, which is the rock exposed at the surface throughout northern NPR-A. The Fig. 9 inset shows this migration pathway from the S3b source rock to the overlying Nanushuk Formation reservoir rock (Houseknecht, 2019). Alternatively, if oil and gas were generated in these S3b (or the S1) source rocks, the geologic setting is ideal to promote lateral migration of buoyant oil and gas northward into the anticline beneath Avak Creek and then vertically upward along the normal fault toward the surface. In fact, if porous reservoir rocks and impermeable sealing rocks are present in the anticline beneath Avak Creek, one or more small pools of oil and gas may be present in the anticline immediately south of the normal fault. In reality, both suggested migration pathways are viable alternatives for the Avak Creek setting. Geochemical Characterization Samples were analyzed by a suite of classical geochemical analyses including API gravity and sulfur content, bulk carbon isotopes of saturated and aromatic hydrocarbon fractions, quantitative whole oil gas chromatography-flame ionization detection (GC-FID), GC-mass spectrometry (GCMS) of isolated saturated and aromatic hydrocarbon fractions (biomarkers) (e.g., Peters et al., 2005). Advanced Geochemical Technologies (AGTs; Dahl et al., 1999; Moldowan et al., 2015) performed by BTI comprise enhanced biomarker assessments by tandem mass spectrometry (GCMS-MS), quantitative diamondoid analysis (QDA), quantitative extended diamondoid analysis (QEDA), and compound specific isotopic analysis (CSIA) of hopane and sterane biomarkers (CSIA-Bh and CSIA-Bs, respectively). Age-diagnostic and source-sensitive biomarker parameters, largely based on GC-MS-MS data, provide an assessment of the thermal maturity, age ranges, organic matter input, and depositional environment of the source(s) of the oil-window components. Diamondoid results provide a platform to assess possible mixed charge contributions and to determine source(s) of both post-mature and oil-window components of extracts and oils. Results of CSIA-Bh and -Bs also provide greater insight into the paleoenvironments of the generative sources. "Biomarker Acids Analysis" also was used in this study to provide evidence for the origin of the surface expressions of the Avak Creek oil occurrences; whether they likely are natural seeps migrating from subsurface sources (reservoirs or directly from the source rock) or were simply spilled petroleum from anthropogenic activities. This analytical technique looks at severity of Appendix D Page 5 of 23 biodegradation and signs of subsurface anaerobic biodegradation versus aerobic biodegradation that may occur at the surface. Overall geochemical results from all the analyses demonstrate that the Avak Creek sample data are consistent with geochemical fingerprints of natural crude oils we have analyzed from production wells and seeps across the North Slope. Figure 10 highlights the progression of analytical chromatograms from GC-FID (whole oil) analysis to GC-MS analysis (biomarkers in isolated saturated and aromatic hydrocarbon fractions) to GC-MS-MS analysis of biomarkers. This demonstrates that with more advanced instrumentation we were able to significantly remove overlapping hydrocarbons and peak interferences and accomplish more accurate hydrocarbon peak identification and quantification. Whole oil GC-FID chromatograms of the Avak Creek samples show similar results to initial data generated by the USCG MSL. The unresolved complex mixture (UCM) of bio resistant compounds indicate biodegradation, with the n-alkanes having been completely biodegraded. Isoprenoids also have been affected; however, peaks are still detectable at the top of the UCM. Loss of volatile, low molecular weight peaks (<C10) likely is due to evaporation. GC-MS-MS biomarker profiles show that the Avak Creek samples look very similar to what we would expect from natural crude oil samples. Biomarkers (steranes and hopanes) do not appear to be biodegraded. It also is important to note that we do not see any significant differences among Avak Creek samples collected from both shoreline and the tundra field site locations. Additionally, no unusual peaks were observed; data looks like standard profiles of petroleum hydrocarbons. All Avak samples show consistent values across key bulk compositional and molecular geochemical parameters (biomarkers, CSIA, and diamondoids) commonly used to infer source rock characteristics such as depositional environment, organic matter input, geologic age, and thermal maturity (Figs. 11-16). Thermal maturity of the Avak Creek samples is in the early oil window (~0.7-0.8 %Ro), consistent with the thermal maturity of the Hue-GRZ in this area. The geochemical results from the Avak Creek samples are exactly where we would expect them to be in terms of thermal maturity (Fig. 11). Regarding lithology of the generating source rock, all the Avak Creek samples are plotting in the middle of this distribution of oils from across the North Slope, emphasizing that their geochemical signatures are strongly indicative of natural crude oil (Fig. 12). The Avak Creek samples cluster together and to nearby (Cape Simpson) Cretaceous oils and seeps, suggesting a common source. This generating source rock is suggested to be the Early Cretaceous Hue-GRZ, mostly Aptian to Albian in age (~126-110 Ma), in the early stages of oil generation. Taxon-specific and age-related biomarker parameters, including the absence of Oleanane (older than the Late Cretaceous, Moldowan at al., 1994) but presence of Bicadinane (Moldowan, unpublished data showing Jurassic and younger occurrence of bicadinane), brackets the age of the Avak Creek source rock as Early Cretaceous (Fig. 13). The Avak Creek samples also show a significantly higher contribution of terrestrial organic matter relative older Jurassic and Triassic typed oils. This likely supports the age of the generating source rock and unique depositional environment discussed above. Appendix D Page 6 of 23 The Hue-GRZ in this area include clastic-rich, siliclastic strata deposited in a more proximal depositional environment allowing for a higher contribution of terrigenous organic matter. In the Avak sample area, the Hue-GRZ was deposited on a submarine ridge (the Barrow Arch) in a surrounding deepwater marine basin. This created a unique, isolated depositional setting with local evidence of exposure surfaces and burrows indicating shallow water. CSIA Isotopic fingerprints of both hopanes (-Bh) and steranes (-Bs) are consistent fingerprints among the Avak Creek samples (and share a similar profile to the Cape Simpson Seismic Line seep (Figs. 14-15). CSIA-Bh results of the Avak Creek samples suggest a more stratified water column with anoxic benthic waters during deposition. CSIA-Bs results provide additional supporting evidence in support of a significant terrigenous organic matter contribution, as indicated by the isotopically heavy C29 values. The Avak Creek sample group is also distinct with elevated (heavier) C28 sterane isotopes. QEDA fingerprints are consistent among the Avak samples (Fig. 16). They also cluster with Cretaceous-typed oils, including nearby Simpson well oils, Cape Simpson seeps, and Fish Creek seep). While there is also overlap with the diamondoid profile of another clastic-rich Jurassic Kingak-sourced oil, the Kingak source rock can be ruled out as an option for generating the Avak Creek oils as it is not locally present in the sample area. Biomarker Acids Analysis identified the presence of tricyclic terpanoic acids and -hopanoic acids in the Avak Creek samples. These compounds are products of biodegradation (not generated by kerogen of the source rock) that only occur in anaerobic conditions, such as biodegradation that occurs in a subsurface reservoir; they have not been identified in aerobic conditions. Results thus suggest that the Avak Creek fluids, or at least some portion of them, emanated as seep that leaked/migrated from underground reservoirs. Additionally, 25-norhopanoic acids, indicators of intense anaerobic degradation, were absent in the Avak Creek samples. This suggests that the biodegradation of these fluids in subsurface reservoirs did not exceed the moderately high level of biodegradation (Rank 7, Figure 3.62, page 254 in Peters and Moldowan, 1993) needed to produce these compounds. Permafrost Quantitative modeling of burial history and petroleum generation indicates that crude oil and natural gas have been generated in source rocks of the Barrow High and the Colville foreland basin to the south during the Cretaceous. Generation began in the Colville foreland basin of southern National Petroleum Reserve in Alaska (NPR-A) during the Early Cretaceous and migrated northward through time such that generation in the Barrow High occurred during the Late Cretaceous (Houseknecht et al., 2012). In contrast, permafrost developed very recently, during the past 2 to 3 million years; Carter and Hillhouse, 1992). These results suggest that deterioration of permafrost only would have an impact on mobilizing crude oil and natural gas if that petroleum migrated out of source rocks, accumulated in shallow traps, and then was remobilized. Crude oil seeps have known on Cape Simpson for hundreds of year or more and clearly have a surface expression. However, shallow core tests completed by the U.S. Navy demonstrate that Appendix D Page 7 of 23 oil also is trapped in reservoirs at shallow depths (10s to 100s ft). We suggest, therefore, that the Avak Creek oil occurrence resulted from a similar process. That is, we propose that crude oil and gas were generated in Lower Cretaceous source rocks (S3b in Fig. 6), migrated northward into the Cape Simpson and Avak Creek areas, and were trapped there at shallow depth. As erosion occurred through the millennia, some of the shallowly trapped oil was liberated to become seeps on Cape Simpson whereas others remained trapped at shallow depth, as indicated by the U.S. Navy drilling on Cape Simpson, and even at the Iko Bay #1 well. The development of permafrost likely froze the shallow oil in place until warming over the past 20 years induced deterioration of the upper permafrost, which resulted in remobilization of the shallow oil and gas. We therefore recommend continued monitoring of the Avak Creek oil occurrence to determine if a significant volume of oil continues to be mobilized. References Botterell, P.J., Houseknecht, D.W., Lillis, P.G, Barbanti, S.M., Dahl, J.E, and Moldowan, J.M., 2021. Geochemical Advances in Arctic Alaska Oil Typing - North Slope Oil Correlation and Charge History. Marine and Petroleum Geology 127, 104878. Carter, L.D., and Hillhouse, J.S., 1992, Age of the Late Cenozoic Bigbendian marine transgression of the Alaskan Arctic coastal plain: Significance for permafrost history and paleoclimate: in Bradley D.C., and Ford A.B., eds.. US Geological Survey Bulletin 1999, Washington, D.C., p. 44-51, https://pubs.usgs.gov/bul/1999/report.pdg Clow, G.D., 2014, Temperature data acquired from the DOI/GTN-P deep borehole array on the Arctic slope of Alaska, 1973-2013: Studies of Earth Systems Science Data, v. 6, p. 201-218, https://essd.copernicus.org/articles/6/201/2014.pdf Clow, G. 2015. Permafrost Temperature Data from a Deep Borehole Array on the Arctic Slope of Alaska, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. https://doi.org/10.5065/D6N014HK Dahl, J.E., Moldowan, J.M., Peters, K.E., Claypool, G.E., Rooney, M.A., Michael, G.E., Mello, M.R., and Kohnen, M.L., 1999. Diamondoid hydrocarbons as indicators of natural oil cracking. Nature 399, 54-57. Houseknecht, D.W., 2019, Petroleum systems framework of significant new oil discoveries in a giant Cretaceous (Aptian-Cenomanian) clinothem in Arctic Alaska: American Association of Petroleum Geologists Bulletin, v. 103, p. 619-652, DOI: 10.1306/08151817281 Houseknecht, D.W., Burns, W.M., and Bird, K.J., 2012, Thermal maturation history of Arctic Alaska and southern Canada basin: in N.B. Harris and K.E. Peters (eds.) Thermal History Analysis of Sedimentary Basins--Methods and Case Histories, SEPM Special Publication 103, p. 199-219, ISBN 978-1-56576-315-9, , https://doi.org/10.2110/sepmsp.103.199 Appendix D Page 8 of 23 Moldowan, J.M., Sundararaman, P., and Schoell, M., 1986. Sensitivity of biomarker properties to depositional environment and/or source input in the Lower Toarcian of SW-Germany. Organic Geochemistry 10, 915-926. Moldowan, J.M., Fago, F.J., Carlson, R.M.K., Young, D.C., Duvne, G., Clardy, J., Schoell, M., Pillinger, C.T., and Watt, D.S., 1991. Rearranged hopanes in sediments and petroleum. Geochimica et Cosmochimica Acta 55 (11), 3333-3353. Moldowan, J. M., Dahl, J., Huizinga, B. J., Fago, F. J., Hickey, L. J., Peakman, T. M. and Taylor, D. W., 1994. The molecular fossil record of oleanane and its relation to angiosperms. Science 265, 768-771. Moldowan, J.M., Dahl, J., Zinniker, D., and Barbanti, S., 2015, Underutilized advanced geochemical technologies for oil and gas exploration and production-1. The diamondoids. Journal of Petroleum Science and Engineering 126, 87-96. Peters, K.E. and Moldowan, J.M. 1993, "The Biomarker Guide. Application of Molecular Fossils in Petroleum Exploration," Prentice-Hall, Englewood Cliffs, New Jersey, 363 p. Peters, K.E., Walters, C.C., and Moldowan, J.M., 2005. The Biomarker Guide, Volume 2: Biomarker and Isotopes in Petroleum Exploration and Earth History, Second Edition. Cambridge University Press, 1155 p. Seifert, W.K., and Moldowan, J.M., 1978. Applications of steranes, terpanes and monoaromatics to the maturation, migration and source of crude oils. Geochimica et Cosmochimica Acta 42, 77-95. Sieskind, O., Joly, G., and Albrecht, P., 1979. Simulation of the geochemical transformation of sterols: superacid effect of clay minerals. Geochimica et Cosmochimica Acta 43 (10), 1675-1679. Sofer, Z., 1984. Stable Carbon Isotope Compositions of Crude Oils: Application to Source Depositional Environments and Petroleum Alteration. AAPG Bulletin 68 (1), 31-49. Zumberge, J.E., 1984. Source rocks of the La Luna Formation (Upper Cretaceous) in the Middle Magdalena Valley, Colombia. In: Petroleum Geochemistry and Source Rock Potential of Carbonate Rocks (J. G. Palacas, ed.). AAPG, Tulsa, OK, 127-133. Appendix D Page 9 of 23 Figure 1. Avak Creek. Photographs of oil occurrence by sample site, provided courtesy of USEPA. Figure 2. Map centered on central North Slope, Alaska, showing main tectonic features, boundaries of National Petroleum Reserve in Alaska (NPRA) and Arctic National Wildlife Refuge (ANWR), and locations of Avak Creek oil occurrence, nearby Cape Simpson oils and seeps, Fish Creek seep, and oil samples in Botterell et al. (2021), listed in Table 1. Photograph of Avak Creek sample locations shown on the left, collected from the shoreline (samples #1-3) and surrounding tundra (samples #4-6), courtesy of the USEPA. Abbreviations: D, Dinkum graben; E, Endicott-Niakuk graben; I, Ikpikpuk basin; P, Dinkum plateau; U, Umiat basin). BH, Barrow high; PB, Prudhoe Bay; SB, Smith Bay. Appendix D Page 10 of 23 Figure 3. False-color composite Landsat image of northernmost Alaska showing in white the boundary of the National Petroleum Reserve in Alaska (NPRA). Petroleum exploration wells drilled prior to 2000 are shown as white dots and those drilled during 2000 to 2010 are shown as yellow dots. Red oval outlines the "Barrow High," an area of high-standing basement rocks in the subsurface. Red star shows location of Avak Creek oil occurrence. Appendix D Page 11 of 23 S N Cross section by Ken Bird Figure 4. South to north geologic cross section showing northward onlap and pinch out Mississippian to Jurassic aged strata. See Figure 5 for ages of formations shown here. Note that datum at top of figure is Lower Cretaceous unconformity at the base of Brookian strata, which are not shown in the figure. Unpublished figure by Ken Bird (USGS retired). Map by Ken Bird Figure 5. Map of Barrow High showing areas where Mississippian to Jurassic aged strata rest directly on Pre-Mississippian basement rocks. Unpublished figure by Ken Bird (USGS retired). Appendix D Page 12 of 23 A B Figure 6. A. Generalized chronostratigraphy of Arctic Alaska showing tectonostratigraphic showing tectonostratigraphic sequence names at right. Series names are shown only for Cretaceous, Paleogene, and Neogene systems. Only stage names pertinent to text are shown. Petroleum source rocks common on the Alaska North Slope include (S1) Shublik Formation, (S2) lower Kingak Shale, and four Brookian units that include (S3a) composite of proximal pebble shale unit (PSU) and gamma ray zone (GRZ) of Hue Shale, (S3b) composite of distal PSU and GRZ, (S4) Cenomanian to Turonian part of Hue Shale, and (S5) distal Paleocene to lower middle Eocene part of Canning Formation. Regional geology and seismic interpretation indicate that only S1 and S3b (highlighted by red) are likely present in the vicinity of the Avak Creek oil occurrence. Note: Time scale is nonlinear! FRANK, Franklinian; LCU, Lower Cretaceous unconformity; Be, Berriasian; Va, Valanginian; Ha, Hauterivian; Ba, Barremian; Ap, Aptian; Al, Albian; Ce, Cenomanian; Tu, Turonian. Abbreviated formation names include: N, Nanushuk; PC, Prince Creek; S, Seabee; SB, Schrader Bluff; T, Tuluvak. Figure from Botterell et al. (2021). B. Same figure as A, but red boxes denote strata absent in Avak Creek area due to nondeposition on Barrow High or erosion following deposition. Vertical yellow lines show strata that were penetrated by the Iko Bay #1 exploration well. Appendix D Page 13 of 23 Figure 7. Regional map of thermal maturity at base of Brookian strata, corresponding to stratigraphic level of source rock S3b (Figure 6). The colors on this map relate to thermal maturity as indicated by vitrinite reflectance levels shown in legend near upper left of figure, with explanation in legend at middle left. Enlarged segment of map (upper right) shows details in study area shown in red rectangle. Figure adapted from Houseknecht, et al. (2012). Appendix D Page 14 of 23 South Barrow Gas Field East Barrow Gas Field Cabot 1 Walakpa Gas Field Intrepid 2 Brontosaurus 1 Avak Creek Oil Occurrence Iko Bay 1 Native Lands Tulageak 1 West Dease 1 Dease Inlet Kuyanak 1 North Simpson 1 East Simpson 2 East Simpson 1 Seep Figure 8. Map of Avak Creek area showing selected exploration wells with names, two-dimensional (2-D) seismic lines (dark gray), known seeps on Cape Simpson (magenta stars), and Simpson Core Tests drilled by U.S. Navy (green circles). Location of Avak Creek oil occurrence shown by pink circled dot just west of Iko Bay 1 exploration well. Red line with blue border is location of seismic line shown in Figure 9. Appendix D Page 15 of 23 Nanushuk etc. West Source S3b Torok etc. East Figure 9. South-north seismic image crossing Avak Creek oil occurrence and Iko Bay 1 well, both near north end of line. Oil and gas generated south of Avak Creek likely migrated northward into the Avak Creek area Migration was driven by buoyancy and likely occurred westward along clinoform surfaces (arrows in inset image) within Torok Formation and into Nanushuk Formation near surface. The arch and associated normal faults beneath Avak Creek are favorable for migration of crude oil into the area of the oil occurrence. Legend below seismic line shows horizons correlated on seismic line; stratigraphic postitions of those horizons and the petroleum source rocks also are shown in Figure 6. Appendix D Page 16 of 23 GC-MS-MS: Saturate Fraction Figure 10. Analytical Chromatograms: GC-FID (whole oil) GC-MS (saturate fraction) GC-MS-MS (saturate fraction). Advanced instrumentation allowed for removal of overlapping hydrocarbons and peak interferences to provide a more accurate view of hydrocarbon profiles and identification of hydrocarbon peaks. Appendix D Page 17 of 23 Figure 11. Thermal Maturity. Increasing values of TA-(C20:21)/(C20:21+C26:28) relative to Ts/(Ts+Tm) reflect a general increase in thermal maturation as indicated by dashed lines and estimated vitrinite reflectance values at top according to the TA - Ro relationship defined in Peters et al. (2005). Appendix D Page 18 of 23 Figure 12. Lithology-sensitive bulk geochemical (A, B) and biomarker parameters (C, D). Among samples of similar thermal maturity, variation in source-related parameters represent differences in lithofacies of the inferred generating source rock among oil families (Seifert and Moldowan, 1978; Sieskind et al., 1979; Zumberge, 1984; Moldowan et al., 1986, 1991; Peters et al., 2005). Stable carbon isotopes of C15+ saturate and aromatic hydrocarbon fractions used to discriminate oil samples generated from a predominance of marine or terrestrial source organic matter as defined by Sofer (1984). Appendix D Page 19 of 23 Figure 13. Source age and organic matter. Age-diagnostic (and taxon-specific) biomarker parameters used to bracket age ranges and discriminate oil families. A) Bicadinane and oleanane indices are highly specific for both Cretaceous and younger sources and terrestrial plant organic matter input. B) Sterane distributions discriminate source organic matter contributions (e.g., marine algal flora, diatoms, terrigenous plane input). Abbreviations: oleanane index ((-oleanane + -oleanane)/(-oleanane + -oleanane + C30H)); bicadinane index (bicadinaneT/(bicadinane-T + C30H)). Appendix D Page 20 of 23 Figure 14. CSIA-Bs (sterane) Isotopic Signatures. Top Left: North Slope oils characterized in Botterell et al. (2021). Bottom: Avak Creek oil samples with nearby Cape Simpson Seismic Line seep inferred to have been generated from a Cretaceous source rock. Figure 15. CSIA-Bh (hopane) Isotopic Signatures. Top Left: North Slope oils characterized in Botterell et al. (2021). Bottom: Avak Creek oil samples with nearby Cape Simpson Seismic Line seep inferred to have been generated from a Cretaceous source rock. Appendix D Page 21 of 23 Figure 16. QEDA Fingerprints. Extended diamondoid concentrations plotted relative to triamantane. Top: North Slope oils characterized in Botterell et al. (2021). Bottom: Avak Creek oil samples with nearby oils and seeps inferred to have been generated from a Cretaceous source rock. Appendix D Page 22 of 23 Figure 17. Subsurface temperature profiles from South Meade and Kuyanak exploration wells south of Avak Creek (see Fig. 7). The South Meade and Kuyanak wells display profiles that reflect initial cooling of shallow (less than ~35 meters) permafrost as higher temperatures induced by circulation of drilling mud during drilling subsided, followed by warming of shallow permafrost inferred as the influence of warming climate. Permafrost inferred to have formed across Arctic Alaska ~2 million years ago (Carter and Hillhouse, 1992). Data and interpretations based on Clow (2014, 2015). Plots adapted from: https://nsidc.org/data/g10015/versions/1 Appendix D Page 23 of 23