Petrographic analysis of two cores (#101 Cañas and Mesita #1) from the Golden Lane (Faja del Oro) / Poza Rica oil fields (Cañas and Mesa Cerrada) along the Tuxpan Platform, Mexico, reveals that Lower Cretaceous and middle Cretaceous reefs developed along the margin of the Platform at this time. One facies in this complex (the El Abra LimestonesLimestone) contains abundant rudists, corals, and benthic/planktic foraminfers. This facies has yielded huge volumes of hydrocarbons. For example, the Potrero del Llano #4, blew out in December, 1910, at a rate exceeding 100,000 barrels of oil per day. It produced 93 million barrels of oil, and is possibly the most productive well ever drilled. Thin sections cut from the #101 Cañas cores (cores 1-4, 6-7, 9-11, and 13-17) demonstrate the following petrographic trends: #1, foraminiferal mudstone with sparite-filled fractures; #2, angular quartz in foraminiferal mudstone; #3, chert overlain by foraminiferal ooze; #4, Cuneolina sp. and Miliolidae; #6, Barkerina barkerensis (Albian); #7, Dictyoconus sp. with gastropods and spar cement; # 9, bitumen with dogtooth spar and bryozoa; #10, bryozoans with moldic porosity; #11, pelletoidal boundstone with limestone clasts and rim cement; #13, corals and meniscus cement in interparticle porosity; #14, oolitic grainstone with oil stains along stylolites; #15, rudists in oil shale with metamorphic quartz clasts; #16, lithic arenite with hematite cement; and #17, subarkose with granite fragments and angular quartz. The other core (Mesita #1 cores 2, 4, and 5) exhibits these variations: #2, Cuneolina sp. with spar cement; #4, orbulinid foraminifers and rudists; and #5, Dictyoconus sp. with spar cement. The thin sections from the #101 Las Cañas and Mesita #1 cores allow insight into a portion of the giant Pimienta-Tamabra (!) petroleum system in the Tampico/Misantla Basin, Mexico. The total reserves of this system are ~66.3 billion barrels of oil and 103.7 trillion cubic feet of natural gas. This is ~836 billion barrels of oil equivalent.