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20°S Auquilco OAEs

Tropical Los Vaca Neuqén (38°S, 290°E)
Arid Molles
This study:
Torsvik et al. (2012)

Paleolatitude (°) 40°S Temperate Humid

60°S continental marine / continental Marine source rock
40°N
[Ma] 200 150 100 Evap5o0rites 0
Smackover
Temperate Bossier Oceanic Anoxic Events (OAEs)
Humid
Paleolatitude (°)
20°N Tropical Arid Louann
Pine Island
Mooringsport
Tuscaloosa

ITCZ pre-rift sequence mari n e ..

0° 100 Gulf of Mexico (26°N, 270°E)
10°S This study:
1a 1b 1c1d 2 3 Torsvik et al. (2012)

[Ma] 200 170 160 150 140 OAEs 50 0

CFGF’13 To W
GO’04
He
Si
P
T
Aa
Bj
BCtal
K
Ti
Be
V
Ha
Ba
Ap
Al
Ce
STCauo
Cam
M
Pa
E
Ol
Mi
PP
O

Late Early Mid. Late Early Cretaceous Late Paleogene Neogene
Triassic Jurassic

Figure 3. In upper panel, the paleolatitudinal evolution of the Neuqén Basin in Argentina (38°S, 290°E) and in lower panel of the Gulf of Mexico offshore Texas
(26°N, 270°E) calculated from the APW path of Table 1 (in South American and North American coordinates, respectively). Errors in age (not shown to enhance
visual clarity of diagram) are ±10 m.y. except for paleolatitudes at 145 and 156 Ma with errors of ±5 and ±1.6 m.y., respectively; errors in paleolatitude (shown as
vertical bars) are equal to ± A95 (cone of 95% confidence of mean paleomagnetic pole). The black arrows highlight the latitudinal drift associated with the Jurassic
polar shift. Included in both diagrams are the paleolatitudes predicted from the Torsvik et al. (2012) APW path for 180–120 Ma (black triangles) with vertical error
bar at 150 Ma. The names of main source and seal rock formations discussed in the text are also reported (e.g., Los Molles, Auquilco, Vaca [ = Vaca Muerta],
Louann, Smackover). Continental, marine—continental or marine sedimentation. Oceanic Anoxic Events (OAEs): To—“Posidonienschiefer” (Toarcian);
W—“Weissert” (Valanginian–Hauterivian); 1a—“Selli” (Early Aptian); 1b—“Paquier” (Late Aptian–Early Albian); 1c—“Toolebuc” (Late Albian);
1d—“Breistroffer” (Late Albian); 2—“Bonarelli” (Cenomanian–Turonian boundary); and 3 (Coniacian–Santonian) (Cronin, 2010). CFGF’13—time scale of
Cohen et al. (2013); GO’04—time scale of Gradstein and Ogg (2004). ITCZ—Intertropical Convergence Zone; He—Hettangian; Si—Sinemurian; P—
Pliensbachian; T—Toarcian; Aa—Aalenian; Bj—Bajocian; Bt—Bathonian; Cal—Callovian; O—Oxfordian; K—Kimmeridgian; Ti—Tithonian; Be—
Berriasian; V—Valanginian; Ha—Hauterivian; Ba—Barremian; Ap—Aptian; Al—Albian; Ce—Cenomanian; Tu—Turonian; Co—Coniacian; Sa—Santonian;
Cam—Campanian; M—Maastrichtian; Pa—Paleocene; E—Eocene; Ol—Oligocene; Mi—Miocene; PP—Pliocene–Pleistocene.

GSA TODAY | DECEMBER 2016 cases, the development of diapirs from the underlying evaporites Moorigsport, Tuscaloosa; Mancini et al., 2008), some of which
and/or other tectonic or salt-related features can, however, provide appear to often coincide with Cretaceous ocean anoxic events
traps for oil. A prominent example is the Gulf of Mexico (Fig. 1) (OAEs) (Fig. 3, lower panel). We note, however, that there is a gap
where the Louann Salt, an important source of oil-trapping salt in OAEs between the Toarcian and early Aptian, a time interval
domes in the Gulf region (Mancini et al., 2008), formed as the that includes the Late Jurassic polar shift and the development of
Gulf dwelled at arid tropical latitudes of 10–15°N in the Middle the source-reservoir-seal system at Ghawar (Fig. 2).
Jurassic (Fig. 3, lower panel; Table 1). As the Gulf drifted to
30–32°N into the presumed temperate belt during the Jurassic DISCUSSION

polar shift, the Late Jurassic Smackover and Bossier source rocks The Jurassic polar shift, whether it represented a generalized
were deposited (Mancini et al., 2008). Subsequently, during the event of continental drift or a whole mantle rotation, constitutes a
Cretacous, the Gulf was stationed at around 30°N and was the novelty of global plate motion. APW paths published before Kent
locus of formation of additional source rocks (Pine Island, and Irving (2010) do not show the Jurassic polar shift in its full

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