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The Geological Society of America Field Guide 25 2012
Sierra de Catorce: Remnants of the ancient western equatorial margin of Pangea in central Mexico José Rafael Barboza-Gudiño* Instituto de Geología, Universidad Autónoma de San Luis Potosí, Manuel Nava 5, Zona Universitaria C.P. 78240 San Luis Potosí, S.L.P, México Roberto S. Molina-Garza Centro de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro Timothy F. Lawton Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA
ABSTRACT The Sierra de Catorce in northern San Luis Potosí, Mexico, represents an uplifted block with exposures of the oldest rocks of the region which include Upper Triassic turbidites interpreted as deposits of a submarine fan system (“Potosí Fan”) and overlying Lower Jurassic volcanic and volcaniclastic strata interpreted as a record of the Early-Middle Jurassic volcanic arc (“Nazas Arc”) of western North America. These lower Mesozoic units, recognized in several exposures in the region, are interpreted as remnants of the ancient western margin of Pangea prior to accretion of Late Jurassic–Early Cretaceous magmatic arc complexes and associated marginal basins that constitute the Guerrero composite terrane in western Mexico and that resulted in construction of a new Pacific margin. A field trip in the Sierra de Catorce and surrounding exposures of the Upper Triassic–Lower Jurassic succession allows observation and discussion of key features that demonstrate the sedimentary and tectonic history of the western equatorial margin of Pangea. INTRODUCTION
faults, which are cut also by west-northwest–striking normal faults. The Sierra de Catorce is reached by an ~200 km freeway from San Luis Potosí to Matehuala and then to Cedral, along the northern side of the Sierra. The village of Real de Catorce, in the internal part of the sierra is reached by a 14 km long road, and the ~2.7 km long “Tunel de Ogarrio,” constructed in 1800 as the access to the old mining district located at an altitude of 2700 m (Fig. 1).
The Sierra de Catorce, located at the eastern edge of the Mesa Central Province, directly west of the Sierra Madre Oriental, in northern San Luis Potosí, Mexico, represents an uplifted block with an internal folded structure and exposures of the oldest rocks of the region. The current horst structure of the sierra is delimited by “basin and range” north-south–striking normal
*
[email protected] Barboza-Gudiño, J.R., Molina-Garza, R.S., and Lawton, T.F., 2012, Sierra de Catorce: Remnants of the ancient western equatorial margin of Pangea in central Mexico, in Aranda-Gómez, J.J., and Tolson, G., eds., [[space for volume title space for volume title space for volume title space for volume title space for volume title]]: Geological Society of America Field Guide 25, p. 1–18, doi:10.1130/2012.0025(01). For permission to copy, contact
[email protected]. ©2012 The Geological Society of America. All rights reserved.
1
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Discovered before 1773, Real de Catorce was an important mining district during the nineteenth and part of the twentieth centuries. The district attracted the attention of Mexican and foreign miners, as well as geoscientists. For geologists, the district offers an interesting stratigraphic section which records the complex tectonic evolution described in several published works (del Castillo and Aguilera-Serrano, 1895; Baker, 1922; Erben, 1956; Mixon, 1963; Bacon, 1978; Cuevas-Pérez, 1985; Zarate del Valle, 1982; López-Infanzón, 1986; Barboza-Gudiño, 1989; Barboza-Gudiño et al., 1999, 2004; Franco-Rubio, 1999; Hoppe, 2000).
Triassic to Lower Jurassic lithostratigraphic units exposed in the Sierra de Catorce, as well as in several places in the Mesa Central, such as Charcas, Presa de Santa Gertrudis, La Ballena, Zacatecas, and Sierra de Teyra, are closely related to the ancient western equatorial margin of Pangea. After collision and suturing of Laurentia and Gondwana during the Late Paleozoic, the region of what today is central Mexico occupied a remnant basin at the westernmost culmination of the Ouachita-Marathon belt, at the west equatorial margin of Pangea. The earliest deposits in this paleo-pacific sub-basin were Middle to Upper Triassic turbidites
28
To Monterrey
33
To Laredo
38
Estación Vanegas Cedral
ZA C ATE CAS N LU IS P OT OS Í
N
SA
263
N
Real de Catorce La Paz
Estación Catorce
Matehuala Santa Rita
Refugio de Coronados
SAN LUIS POTOSÍ
Villa de Guadalupe
eón vo L Nue í otos is P
Lu San
Guadalupe del Carnicero
258
258
San Francisco Charcas Estación Charcas
San Rafael
Entronque El Huizache
Venado
63
253
Moctezuma
57
To Zacatecas
16
Guadalcázar
Arista
49
La Ballena
Villa Hidalgo slp Ahualulco
La Pendencia Villa Hidalgo zac.
248
Pinos
Potosí
SAN LUIS POTOSÍ
San Luis
Zacatecas
Mexquitic
To Ríoverde
248
70
Key areas
80
243
To Cd. del Maíz
253
57
JA LIS CO
243
km
Ojuelos 23
0
10
20
50
GUANAJUATO GUANAJUATO 28
To Queretaro 33
Figure 1. Locality map and access to the selected areas.
38
fld025-01 1st pgs page 3 Sierra de Catorce
3
In our interpretation, the Potosí Fan was formed in a basinal setting at the western margin of Pangea. As a consequence of latest Triassic–Early Jurassic subduction along this continental margin, the Potosí Fan was deformed and uplifted, so that the first volcanic deposits of the Nazas Formation are subaerial and rest unconformably on the Triassic Zacatecas Formation. The Nazas Formation is unaffected by the intense folding and thrusting registered in the Triassic rocks. Deposits of La Joya Formation represent development of an erosional unconformity following the main period of volcanic activity and erosion of the arc in an extensional setting. The main goal of this excursion is to visit some of the Lower Mesozoic stratigraphic units (Upper Triassic–Middle Jurassic)
known as the Zacatecas Formation and interpreted as deposits of a submarine fan named the Potosí Fan (Silva-Romo et al., 2000). Deposition of the fan was followed by deposition of volcanic and volcaniclastic strata of the Lower Jurassic Nazas Formation, interpreted as remnants of the Early Jurassic continental volcanic arc, known also as “Nazas Arc.” Overlying the Nazas succession, the La Joya Formation, consisting of Middle to Upper Jurassic alluvial to lagoonal and shallow marine deposits, represents a basal transgressive succession in the region (Michalzik, 1988). This unit grades upsection to the Upper Jurassic–Cretaceous carbonate and evaporitic successions of the Gulf Series which are widely distributed from north-central to northeastern Mexico (Figs. 2 and 3).
101°
Monterrey
N
COAHUILA
Juarez
Saltillo ra er Si
NUEVO LEÓN
de co ul m Ji
Si de
Ra m
Rodeo Caopas
S.MARCOS
M
n
de
ire z
Galeana
liá Ju
DURANGO
ra
n Sa S.
er ra
S.
r e ad
a
yr
Te
S i e r r a
Si
er
Aramberri Miquihuana
Catorce
Mesa Central
S Cha. de rcas
Sierra de
Matehuala
ZACATECAS
Charcas
SAN LUIS POTOSÍ
O r i e n t a l
al nt de ci O c
Huizachal Valley alley
TAMAULIPAS 50 km
La Ballena
eS alin as
Zacatecas
S. d
23°
e M a d r
24° 24°
La Boca Canyon
CaAbB aA RaOnSlleLrLoEsC yoCn.
G. Palacio Torreón orreón Villa
San Luis Potosí
Cenozoic (Neogene) cover
Jurassic-Cretaceous volcanosedimentary sequence
Cenozoic volcanics
Pre-Mesozoic rocks and Upper Triassic-Lower Jurassic marine-continental red beds and volcanics
Upper Jurassic-Cretaceous sedimentary cover
Thrust fault
Normal fault
Figure 2. Synthesis of regional geology.
fld025-01 1st pgs page 4 Barboza-Gudiño et al.
QUATER. PALEOGENE NEOGENE
SERIES
Ma STAGE HOLOCENE
PLIOCENE MIOCENE
UPPER
CRETAEOUS
37
EOCENE
55 67
PALEOCENE MAASTRICHTIAN
71.5
CAMPANIAN
83
SANTONIAN
86
CONIACIAN
89
TURONIAN
91 CENOMANIAN
97.5 ALBIAN
108
APTIAN
NEOCOMIAN
LOWER
5.1 23.7
OLIGOCENE
BARREMIAN
114
UPPER
Basalt Quartzmonzonit 53 Ma Mudstone - Sandstone (Caracol Formation) Limestone - Mudstone (Indidura Formation) Limestone (Cuesta del Cura Formation) Limestone - Marl (Formación Tamaulipas Superior Formation) Marl -mudstone (La Peña Formation)
140
Siltstone - Marl (La Caja Formation)
KIMMERIDGIAN
OXFORDIAN
160
CALLOVIAN M IDDLE
Conglomerate
Marl - Mudstone (Taraises Formation)
VALANGINIAN
TITHONIAN
JURASSIC
Alluvium
Limestone (Tamaulipas Inferior Formation)
HAUTERIVIAN
BERRIASIAN
M E S O Z OI C
0.01
PLEISTOCENE 1.68
SENONIAN
TERTIARY
CENOZOIC
ERA System
4
Limestone (Zuloaga Formation) Siltstone-Sandstone Polimictic Conglomeratebreccia Rhyolitic Porphyr (174.7 ± 1.3)
BATHONIAN BAJOCIAN AALENIAN
184 TOARCIAN
Dacit
LOWER
PLIENSBACHIAN
Andesit
SINEMURIAN
HETANGIAN
210
TRIASSIC
UPPER
230 MIDDLE
Volcanic succession (Nazas Formation)
andesíticbasaltic dike Sandstone-mudstone Cerro El Mazo beds siliciclastic succession (”Fm. Zacatecas”)
243 LOWER
CARBON.
PALE O Z O I C
250 PERMIAN
La Joya Formation
290
PENNSYLVANIAN
No deposits MISSISSIPPIAN
360
Figure 3. Stratigraphic column of the Sierra de Catorce.
fld025-01 1st pgs page 5 Sierra de Catorce which crop out in several places of the Mesa Central province, and whose tectonic setting is interpreted as linked to the evolution of the ancient margin of Pangea, prior to opening of the Gulf of Mexico. These units are particularly well preserved in the Sierra de Charcas, and nicely exposed in Cañón General of the Sierra de Catorce. In Cañón General, exposures of the complete stratigraphic column of the region allow unambiguous reconstruction of tectonic setting and, therefore, they are of great interest for understanding the western Pangea and Cordilleran evolution. We will show that the Potosí Fan is a quartz-rich turbidite succession composed of detritus eroded from the East Mexico Arc (Dickinson and Lawton, 2001), as well as from Grenville and Pan African basement sources. This suggests that basement uplifts associated with Triassic rifting existed at that time. Defor23°°10′
5
mation of the Potosí Fan is not well understood, but accretionary prism and subduction complex settings have been proposed (Centeno-García, 2005; Anderson et al., 2005). Although this interpretation is somewhat speculative, it is clear that shortening and thrust faulting registered in the Triassic succession, predated less deformed Jurassic arc volcanic rocks. DAY 1 Stop 1.1. Charcas: 200 m Trip along the Arroyo San Rafael (274188 2553577) The Arroyo San Rafael is placed few kilometers west of Charcas, San Luis Potosí (Fig. 4) and drains a large range located in
101°°10′
23°°10′
B
Cenozoic cover oy o Ar r Las m Pal as
Late JurassicCretaceous limestone
LA TRINIDAD
Ar roy
MORELOS oC
ha
rca sV ieja
SAN ANTONIO DE LAS HUERTAS
s
Lower to Middle Jurassic redbeds Figure 4. Geological map of the La Trinidad Anticlinorium, west of Charcas showing the location of Arroyo San Rafael and Arroyo San Antonio.
23°°05′ EL PERDIDO EL LLANO
Lower Jurassic volcanic rocks
SAN RAFAEL
POTRERO EL LLANO
Triassic marine succession Sierra de Catorce
N
C
Matehuala
B Sierra de Charcas Zacatecas
A
Sierra de Salinas 0 50 100
San LuisPotosí Rioverde Valles 200 km
Normal fault
1 2
3
101°°15′
San Luis Potosí
2 km 23°°00′
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Barboza-Gudiño et al.
an uplifted area known as La Trinidad Anticlinorium. It contains the best preserved exposures of Upper Triassic strata (Zacatecas Formation, after Martínez-Pérez, 1972, or La Ballena Formation, following Centeno-García and Silva-Romo, 1997), consisting of massive thick-bedded sandstone, conglomeratic sandstone, and turbidites with partially developed Bouma sequences and interbedded subordinate shales. Some beds contain common graded bedding. Other sedimentary structures include load and groove casts –which constitute the most common sole marks and slump structures. The clastic components of the sandstone are quartz, feldspar, detrital mica, and shale intraclasts in a matrix of detrital and diagenetic quartz, muscovite+illite, and chlorite (Hoppe et al., 2002). The resulting lithofacies assemblage corresponds to “facies A,” “facies B,” and “facies C” of Mutti and Ricci Lucchi (1972), interpreted as channel and channel margin environments (Fig. 5). Subordinate facies “D,” “E,” “F,” and “G” (suprafan lobe, levee, and inter-channel flats), corresponding to a midfan or suprafan zone, are especially well exposed at Arroyo San Rafael. Also interesting are excellent exposures of a wild flysch, consisting of decimeter-sized to several meter–sized intraformational sandstone blocks, embedded in a sandstone-siltstone and mudstone matrix, which correspond to facies “F” of Mutti and Ricci Lucchi (1972). A Late Triassic age for this succession is well established through uncommon ammonites (Early Carnian Juvavites sp. reported by Cantú-Chapa, 1969, as well as Carnian Anatomites aff. herbichi and Aulacoceras sp., reported by Gallo-Padilla et al., 1993), conodonts (Carnian Neogondolella polygnatiformis and Epigondolella primitia, reported by Cuevas-Pérez, 1985), and results of detrital zircon geochronology (Barboza-Gudiño et al., 2010) that yielded an Early Triassic maximal depositional age of ca. 230 Ma for a sample of medium-grained sandstone collected from the Arroyo San Rafael. The main clusters of individual zircon ages reported for this sample (Fig. 6) and their possible
Figure 5. General features of the Triassic turbiditic sequence exposed along the Arroyo San Rafael, west of Charcas.
source are as follows: 290–220 Ma (Permo-Triassic east Mexico magmatic arc); 440–400 Ma (peri-Gondwanan magmatic assemblages); 700–500 Ma (Pan-African-Brasiliano basement); and 1300–900 Ma (Grenvillian basement). The Triassic turbiditic succession exposed west of Charcas is interpreted as part of the “Potosí Fan” (Silva-Romo et al., 2000; Centeno-García, 2005), a submarine fan deposited in a basinal setting during Middle to Late Triassic at the paleo-margin of Pangea or in a remnant basin at the westernmost culmination of the Ouachita-Marathon belt. Stop 1.2. Charcas: 300 m Trip along the Arroyo San Antonio (276995 2555811) West of Charcas, in the Arroyo San Antonio, at the eastern extreme of La Trinidad Anticlinorium, there are exposures of a volcanic succession of Early to Middle Jurassic age. Although the volcanic rocks in Arroyo San Antonio are in tectonic contact with the Triassic Zacatecas Formation, in other sections measured in the region, the volcanic succession rests unconformably on the Triassic rocks. The volcanic rocks, exposed in several isolated outcrops from west to east along the Arroyo San Antonio, consist of rhyodacitic ash flow tuff (ignimbrites), welded basal vitrophyre, distorted spherulites and vapor zones, massive welded zones, volcaniclastic breccias and epiclastic strata (Fig. 7). The most common structures observed in the field are eutaxitic structures, fiamme, the already described spherulites, lithophysae, and collapsed pumice. Petrographic and reconnaissance geochemical studies in several localities of comparable rocks in the region, included rocks of Charcas (Barboza-Gudiño et al., 2008) indicate a continental volcanic arc setting. To the west along the arroyo, basaltic-andesitic lava flows are well exposed; commonly they occur as brecciated lava flows, which contain angular fragments with common puzzle-structure consisting of tightly packed angular clasts. Petrographic examination reveals porphyritic, trachytic, and pilotaxitic textures. Several lithic fragments that occur in the previously described rhyodacitic flows are trachytic andesites, suggesting that the andesitic lava flows are older than the rhyodacitic pyroclastic flows and were incorporated in the rising magmas that erupted to form the pyroclastic succession. The andesitic lava flows unconformably underlie clastic deposits of the Callovian-Oxfordian La Joya Formation. This clastic sequence grades upwards into limestones of the Oxfordian Zuloaga Formation. La Joya consists of sandstone, conglomerate, and mudstones. Conglomerate clasts are dominated by volcanic rocks, which we infer were derived from the Nazas Formation. The age of the volcanic succession is well established by a U-Pb date for a rhyodacitic ignimbrite, 29 concordant zircon ages from the rock yielded a mean age of 176.8 +4.9/–1.7 Ma, a rather Toarcian/Aalenian boundary age (Zavala-Monsiváis et al., 2012). An Early to Middle Jurassic age for the succession is likewise supported by its stratigraphic relations, in which the
fld025-01 1st pgs page 7 Sierra de Catorce
7
166 Ma Middle Jurassic La Joya Formation Miquihuana
210 Ma Lower Jurassic C. El Mazo beds Los Catorce
225 Ma Upper Triassic Charcas
238 Upper Triassic Los Catorce
219
Upper Triassic San Marcos
Figure 6. Plots of Paleozoic to Jurassic published detrital zircon data from northeastern Mexico. The plots are probability curves, showing maximal deposition age of the sediments.
215 Ma Upper Triassic La Boca
530 Ma
Paleozoic Aramberri
Paleozoic Caballeros
458 Ma
0
1.0
Age (Ga)
2.0
volcanic succession overlies the Late Triassic Zacatecas Formation and unconformably underlies the Callovian–early Oxfordian La Joya Formation. The Nazas volcanic succession has been correlated by lithological similarity and stratigraphic position with volcanic successions exposed in Durango, Zacatecas, and Coahuila (Nazas Formation), and with volcanic-volcaniclastic successions exposed in southern Nuevo León, Tamaulipas, and other localities in western
3.0
San Luis Potosí State (Table 1). These volcanic rocks are thus considered part of the Early Jurassic continental volcanic arc, located along the paleo-margin of Pangea, possibly extending from California, through Sonora (Mauel et al., 2011), and into eastern Mexico. DAY 2 Stop 2.1. Real de Catorce (“Mirador”) (310202 2622353)
Figure 7. Outcrops of the Nazas Formation. Arroyo San Antonio, west of Charcas. (A) Pyroclastic flow; (B) vitrophyre at the base of a younger welded ash flow tuff or ignimbrite; (C) spherulitic horizon of the same ash flow tuff; and (D) ignimbrite.
The point known as “Mirador,” at the entrance to the Ogarrio tunnel, offers a good regional overview of the region’s rocks and style of deformation of the Jurassic-Cretaceous succession of the Sierra de Catorce uplift. Cretaceous limestones are well exposed along the road to Real de Catorce, and at this point Upper Jurassic medium-bedded limestone of the upper Oxfordian Zuloaga Formation (Reyeros de Castillo, 1978) and marls of the Kimmeridgian-Berriasian La Caja Formation (Olóriz, et al., 1999) are well exposed. They are intensely deformed by folding and thrusting as a result of Laramide shortening, which also produced uplift of the sierra and detachment of its mostly calcareous cover. The detachment zone is at the contact between shale of the top of La Joya Formation and limestone of the Zuloaga Formation. This weak zone allowed independent deformation of the cover into north-northwest–trending asymmetrical and overturned fold structures. The general asymmetry of these folds is to the east-northeast. The age of folding is constrained between
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Barboza-Gudiño et al. TABLE 1. REPRESENTATIVE ISOTOPIC AGES OF LOWER TO MIDDLE JURASSIC VOLCANIC ROCKS FROM THE NAZAS FORMATION IN NORTH-CENTRAL TO NORTHEASTERN MEXICO Locality State Rock type Method Material dated Age Source (Ma) Caopas Zacatecas Meta-rhyolitic sub-volcanic Rb-Sr Whole rock 195 ± 20 Fries and Rincón-Orta (1965) Caopas Zacatecas Meta-rhyolitic sub-volcanic Rb-Sr Whole rock 156 ± 40 Fries and Rincón-Orta (1965) Caopas Zacatecas Meta-andesite (rodeo formation) K-Ar Hornblende 183 ± 8 López-Infanzón (1986) Caopas Zacatecas Meta-rhyolitic sub-volcanic U-Pb Zircon 158 ± 4 Jones et al. (1995) 40 Villa Juárez Durango Rhyolite Ar/39Ar Plagioclase 195.3 ± 5.5 Bartolini and Spell, (1997) Catorce San Luis Potosí Rhyolite U-Pb Zircon 174.7 ± 1.3 Barboza-Gudiño et al. (2004) Charcas San Luis Potosí Rhyolitic ignimbrite U-Pb Zircon 176.8 +4.9/–1.7 Zavala-Monsiváis et al. (2012) Coherent grains Huizachal Tamaulipas Rhyolitic ash flow U-Pb Zircon 189.0 ± 0.2 Fastovsky et al. (2005) Aramberri Nuevo León Rhyolitic ignimbrite U-Pb Zircon 193.1 ± 0.3 Barboza-Gudiño et al. (2008) Huizachal Tamaulipas Rhyolite U-Pb Zircon 194.1 +4.1/–4.5 Zavala-Monsiváis et al. (2009) Aramberri Nuevo León Rhyolitic ignimbrite U-Pb Zircon 189.5 ± 3.8 Zavala-Monsiváis et al. (2009) Note: See Figure 2 for location of the areas.
the Campanian-Maastrichtian folded successions and the oldest unfolded rocks or structures in the area. Specifically, for the Sierra de Catorce, unfolded rocks are middle Eocene quartzmonzonitie dikes. These dikes also crop out in the “Mirador” point as a porphyritic rock consisting of idiomorphic centimetersized white feldspar and plagioclase crystals and minor quartz in a microcrystalline, gelb to gray and green matrix. Stop 2.2. Real de Catorce (“Puerta del Sol”) (306924 2621952) View of the Cañón General (General Canyon of Sierra de Catorce): Polymictic conglomerate and conglomeratic red sandstones of La Joya Formation (Callovian-Oxfordian) form a prominent cliff west of Real de Catorce, and offer a panoramic view of the stratigraphic units exposed in the Cañón General (Fig. 8). The units include from base to top, marine beds of the Upper Triassic Zacatecas Formation, Lower Jurassic marine marginal facies, and interlayered greenstone informally named “Cerro El Mazo beds,” rhyolitic, dacitic, and andesitic volcanic rocks of the Lower to Middle Jurassic Nazas Formation, continental to shallow marine conglomerate and red sandstone of La Joya Formation, and limestone of the Zuloaga Formation. The basal part of the Zuloaga Formation constitutes an intensely sheared zone, which resulted from Laramide detachment faulting. The La Joya Formation was defined by Mixon et al. (1959) as a Middle to Late Jurassic conglomeratic redbed sequence exposed in the Huizachal-Peregrina Anticlinorium. They proposed a type locality at Rancho La Joya Verde in the Huizachal Valley, Tamaulipas, ~200 km east of Real de Catorce. La Joya Formation consists of an upward fining megasequence composed of a basal polymictic breccia and conglomerate-fanglomerate facies overlain by red sandstone, siltstone, and mudstone. The clastic components of La Joya basal breccia in Real de Catorce are volcanic, sedimentary, and light-colored metamorphic rocks, as well as white hydrothermal quartz. In the Huizachal area, the main detrital components are gneiss, schist or phyllite, and quartz. La Joya Formation varies locally in its thickness, ranging from a few meters to as much as 200–300 m, and is absent in some localities in northeastern Mexico.
The different facies of La Joya Formation record several depositional environments, interpreted by Michalzik (1988) as follows: fanglomerates, channels and distal alluvial fan conglomerates, shallow-marine carbonates and caliche concretions and crusts, fine-grained alluvial plain deposits, and lagoonal to sabkha evaporites. The age of the La Joya Formation is known only from its stratigraphic position, overlying Lower Jurassic volcanic rocks, and underlying Oxfordian limestone of the Zuloaga Formation. Detrital zircon geochronology results yielded a maximal depositional age of ca. 170 Ma, a rather Bajocian age (Table 2; Fig. 9), in agreement with its stratigraphic position and the Early to Middle Jurassic age of volcanic rocks exposed northwest of Real de Catorce and contained as clastic fragments in a basal breccia of La Joya Formation. Rubio-Cisneros and Lawton (2011) reported a single younger grain age of 163.6 ± 2.6 Ma, a rather Callovian age from La Joya Formation in the Huizachal Valley. Stop 2.3. Cañada Ojo de Agua (El Salto) (306272 2625008) About 5 km north-northwest of Real de Catorce, at Cañada Ojo de Agua or El Salto, a conspicuous rhyolitie dike exhibiting steeply dipping banding underlies La Joya Formation. At the same locality, La Joya Formation is composed of conglomerates with a variety of volcanic rocks as angular to subrounded pebbles and cobbles up to several cm in diameter. These include rhyolitic fragments identical to the rhyolite of the dike. The rhyolite has a porphyritic texture, with hypidiomorphic quartz phenocrysts in a groundmass of totally kaolinitized feldspar. The rhyolitic dike is strongly altered and affected by subsequent silicification of the rock. Locally, foliation with lepidoblastic texture results from the occurrence of oriented sericite associated with a dynamic metamorphism. The analysis of three zircon grains from a sample of a rhyolite collected at this point yielded an age of 174 Ma, a rather early Aalenian age on the basis of a single concordant zircon, and
Figure 8. Geological map of the northwestern Sierra de Catorce.
fld025-01 1st pgs page 9 100°5′
Sierra de Catorce
9
Kt Cz-Lu
N
T-Q al
T-Q al
Kace Cz 2200
Kapa Cz-Mg
Kap Mg-Lu T-Q al
Alluvium (silt, sand, gravel) Neogene-Quaternary
Tmi Ba
Basalt, Miocene
Kt Cz-Lu
Limestone-shale Upper Cretaceous (Turonian/Indidura Formation )
Jco Lm-Ar 70
71 23°45′
23 45
73
Khba Cz Pad
C. EL PAISANO
13
C. LA CALABAZA
89
00
Kace Cz 22
Limestone-marl (Upper Aptian-Albian, Tamaulipas Superior Formation)
Kap Mg-Lu
Marl-Shale (Aptian, La Peña Formation )
Khba Cz
Thick bedded limestone, chert nodules (HauterivianBarremian, Tamaulipas Inferior Formation)
KbevMg-Lu
Marl-shale (Berriasian-Valanginian, Taraises Formation)
Jkt Lm-Mg
Siltstone, marl (Kimmeridgian-Tithonian, La Caja Formaction)
C. EL AGUILA
JmRi Kapa Cz-Mg
EL SALTO TR Lu-Ar
Jok Cz 8
KbevMg-Lu
A. El Tunalillo
Kapa Cz-Mg
moncillo
C. LA CAMPANA
Oj od eA gu a
Thin bedded limestone with black chert bands (Albian-Cenomanian, Cuesta del Cura Formation)
00
POBLAZON
Tmi Ba
43
Kace Cz
A. El Ja
28
Ca ña da
C. LA CUEVA DEL SOL
28 00
re
T-Q al
Jbac Cgp
oyote
Jkt Lm-Mg
C A. El
85 Tmi Ba
C. EL INDIO
3000
Kapa Cz-Mg
89
LA BUFA
65
C. PUERTO DEL AIRE
20 TR Lu-Gr
ELMAZO TO DUC E U AC
SANTA CRUZ DE CARRETAS
52 280
88
Ji Ar-Lu
A
A′
Tmi Ba
Ge ner
SOCAVON DE al d e C PURISIMA ato rce
Jok Cz
Jco Lm-Ar
Red siltstone-sandstone (CallovianOxfordian, Upper part of La Joya Formation)
JbacCgp
Polygmictic Conglomerate-breccia (Bathoniano-Calloviano, Lower part of La Joya Formation)
0
65
LOS CATORCE
83
Limestone (Oxfordian-Kimmeridgian, Zuloaga Formation)
C. LA DESCUBRIDORA
Jkt Lm-Mg
Khba Cz
Jok Cz
C. EL ZANJON
Tmi Ba
JmRi
29
Rhyolite (Nazas Formation)
43 REAL
7 A. El Pino
DE CA
T ORCE Jok Cz
85
30 ALAMITOS DEL PALILLO
18
28
00
55
C. LA MISIÓN
Siliciclastic turbiditic succession Upper Triassic (Zacatecas Formation) Dykes, cuarzo-monzonite (Eocene)
00
30
2800
TR Lu-Gr
70 2800
25
Sandstone and shale (Lower Jurassic, Cerro El Mazo beds)
C. EL QUEMADO
50
REGO
23°40′
Ji Ar-Lu
PUERTO DE PALILLO
JbacCgp
A. El Tecolote
Volcanics dacitic-andesitic (Lower Jurassic) (Nazas Formation)
JimA
C. EL RUCIO
CAÑON EL BOR
80
detachment
C, GRANDE
23°40′
Jco Lm-Ar
C. EL ARCO
Normal fault
35
Khba Cz
04
Jco Lm-Ar
2000
62
Inferred normal fault anticline
T-Q al
JimA
JbacCgp
Kt Cz-Lu
100°5′
18
A. M
12
A.
0
zas
atan
LAS ADJUNTAS
0
00
24
syncline
65 SAN JUAN DE MATANZAS Sa
nI
Jok Cz
25
gn ac
io
A′
38
bedding cleavage (S1) frequently subparallel to bedding (S0)
75
2800 A 2600 2400 2200 2000
topography
3
a l Anim A. E
Kapa Cz-Mg
2
23
cleavage (S2)
A
A′ section
1 km
fld025-01 1st pgs page 10 10
Barboza-Gudiño et al.
U ppm
TABLE 2. DETRITAL ZIRCON AGES FOR A SAMPLE FROM LA JOYA FORMATION, REAL DE CATORCE AREA Apparent ages Isotope ratios 206 206 (Ma) Pb/ Pb*/ ± ± Error Best age U/Th 207 204 207 206 207 206 Pb Pb* % (Ma) ± ± ± ± Pb*/ Pb*/ (%) corr. 206Pb*/ Pb*/ Pb*/ 235 238 238 235 207 U* % U U* (Ma) U (Ma) Pb* (Ma) 3.3
1
357
15512
1.5
20.4754
0.0261
1.1
0.32
166.2
1.9
164.5
5.4
140.1
78.6
166.2
2
194
5229
1.8
19.5030 11.7 0.1929 11.9 0.0273
2.4
0.20
173.5
4.1
179.1
19.6
253.2
269.3
173.5
4.1
3
258
10826
2.1
20.5031
1.9
0.48
179.7
3.4
176.7
6.5
136.9
82.2
179.7
3.4
4
132
3724
1.0
17.2239 12.8 0.2267 13.2 0.0283
3.0
0.23
180.0
5.4
207.5
24.7
532.0
281.7
180.0
5.4
5
507
12947
1.8
19.3236
1.0
0.26
195.5
1.9
201.6
7.0
274.4
84.2
195.5
1.9
6
181
10374
2.0
19.9201
3.4
0.2357
3.5
0.0341
1.0
0.29
215.9
2.1
214.9
6.8
204.3
78.3
215.9
2.1
7
254
7721
1.3
18.3306
2.9
0.2877
3.7
0.0383
2.4
0.63
242.0
5.6
256.8
8.4
393.9
64.6
242.0
5.6
8
684
25725
1.1
19.0884
1.8
0.2779
3.7
0.0385
3.3
0.88
243.4
7.8
249.0
8.2
302.4
40.7
243.4
7.8
9
253
4403
0.5
14.9900 18.6 0.3642 18.9 0.0396
2.9
0.16
250.3
7.2
315.3
51.2
828.7
392.0
250.3
7.2
10
207
10826
1.4
19.7918
5.8
0.2761
5.9
0.0396
1.3
0.21
250.5
3.1
247.5
12.9
219.2
133.3
250.5
3.1
11
80
4508
1.5
22.4680
8.3
0.2442
8.4
0.0398
1.4
0.16
251.6
3.4
221.9
16.7
-82.5
202.6
251.6
3.4
12
273
18603
2.0
19.9656
3.6
0.2752
4.1
0.0399
2.1
0.50
251.9
5.1
246.9
9.1
199.0
83.0
251.9
5.1
13
477
26838
1.9
19.3655
3.8
0.2844
4.0
0.0399
1.3
0.32
252.5
3.2
254.1
9.0
269.4
87.3
252.5
3.2
14
166
7756
1.2
19.8495
9.6
0.2783
9.7
0.0401
1.8
0.19
253.2
4.6
249.3
21.5
212.5
222.1
253.2
4.6
15
298
19761
1.1
19.9041
2.5
0.2788
3.5
0.0402
2.4
0.69
254.4
6.0
249.7
7.7
206.1
58.7
254.4
6.0
16
172
9125
0.9
18.9678 13.0 0.2930 14.8 0.0403
7.1
0.48
254.7
17.7
260.9
34.1
316.8
296.6
254.7
17.7 6.1
3.5
3.7
0.1759
0.1901
0.2197
3.5
± Ma
4.0
3.8
0.0283
0.0308
1.9
17
403
26992
1.6
19.6869
1.9
0.2826
3.1
0.0403
2.4
0.79
255.0
6.1
252.7
6.9
231.5
43.9
255.0
18
282
17070
1.0
19.4055
5.3
0.2869
5.4
0.0404
1.3
0.24
255.1
3.3
256.1
12.3
264.7
120.9
255.1
3.3
19
679
16618
0.7
18.7672
1.9
0.3007
2.4
0.0409
1.4
0.57
258.5
3.4
266.9
5.5
340.9
43.6
258.5
3.4
20
174
9559
1.5
19.8414
4.7
0.2886
5.4
0.0415
2.6
0.48
262.3
6.7
257.4
12.3
213.4
110.0
262.3
6.7
21
151
6395
1.1
17.8541
7.6
0.3212
7.7
0.0416
1.2
0.15
262.7
3.0
282.8
19.1
452.7
169.7
262.7
3.0
22
320
15386
1.4
19.4941
6.1
0.2974
6.3
0.0420
1.5
0.24
265.5
3.9
264.3
14.7
254.2
141.3
265.5
3.9
23
336
8666
1.5
18.8629
4.6
0.3083
4.9
0.0422
1.6
0.32
266.3
4.1
272.9
11.7
329.4
105.1
266.3
4.1
24
603
30580
1.3
19.1531
2.0
0.3048
2.2
0.0423
1.0
0.45
267.3
2.6
270.2
5.3
294.6
45.9
267.3
2.6
25
82
5121
1.6
19.4898 10.0 0.3061 10.1 0.0433
1.0
0.10
273.1
2.7
271.2
23.9
254.7
230.6
273.1
2.7
26
484
30114
1.2
18.8660
1.5
0.3215
1.8
0.0440
1.0
0.55
277.5
2.7
283.0
4.5
329.0
34.4
277.5
2.7
27
83
3455
1.4
17.9821
9.5
0.3466
9.9
0.0452
2.7
0.28
285.0
7.6
302.2
25.8
436.8
211.8
285.0
7.6
28
337
21476
4.7
19.7858
3.9
0.3165
4.5
0.0454
2.1
0.48
286.4
6.0
279.2
10.9
219.9
91.3
286.4
6.0
29
954
28868
1.3
19.3410
2.4
0.3243
4.1
0.0455
3.3
0.81
286.8
9.3
285.2
10.2
272.3
54.8
286.8
9.3
30
96
7014
2.3
19.3639 10.3 0.3307 10.4 0.0464
1.5
0.14
292.6
4.3
290.1
26.3
269.6
236.6
292.6
4.3
31
237
16048
1.7
18.2202
6.6
0.3556
6.7
0.0470
1.1
0.16
296.0
3.2
308.9
17.8
407.5
147.8
296.0
3.2
32
137
7032
2.6
18.3147
5.8
0.3628
5.9
0.0482
1.2
0.21
303.4
3.6
314.3
16.0
395.9
130.3
303.4
3.6 3.3
33
38
3563
1.7
17.8392 17.2 0.4110 17.2 0.0532
1.0
0.06
334.0
3.3
349.6
51.0
454.6
384.5
334.0
34
349
57897
3.7
17.1415
2.8
0.6897
3.0
0.0857
1.2
0.40
530.3
6.2
532.6
12.5
542.5
60.2
530.3
6.2
35
625
57313
11.2
17.2178
1.8
0.6920
3.3
0.0864
2.7
0.83
534.3
13.8
534.0
13.5
532.7
39.9
534.3
13.8
36
329
51643
3.7
16.2093
1.8
0.8907
2.1
0.1047
1.0
0.48
642.0
6.1
646.8
10.0
663.5
39.3
642.0
6.1
37
80
10052
1.9
15.6931
2.1
0.9799
2.5
0.1115
1.4
0.55
681.6
9.0
693.5
12.6
732.4
44.3
681.6
9.0
38
148
15071
2.4
13.8840
2.3
1.1450
4.6
0.1153
4.0
0.86
703.4
26.5
774.9
25.0
986.6
47.6
703.4
26.5
39
474
24035
2.9
15.5665
2.7
1.0426
4.2
0.1177
3.3
0.77
717.3
22.1
725.2
21.8
749.5
56.2
717.3
22.1
40
529
76013
7.2
14.5866
2.7
1.2233
5.3
0.1294
4.6
0.86
784.5
34.0
811.3
29.8
885.4
55.4
784.5
34.0
41
369
73931
1.4
14.4126
2.5
1.3920
2.8
0.1455
1.1
0.41
875.7
9.3
885.6
16.3
910.2
51.9
875.7
9.3
42
262
52129
6.6
14.1546
2.5
1.4983
3.7
0.1538
2.7
0.73
922.3
23.5
929.7
22.7
947.2
52.0
922.3
23.5
43
109
33943
1.5
14.2724
2.6
1.5118
3.1
0.1565
1.8
0.56
937.3
15.3
935.2
19.1
930.2
53.1
937.3
15.3
44
41
10409
1.4
14.1585
3.7
1.5547
3.9
0.1597
1.2
0.31
954.8
10.5
952.4
23.9
946.7
75.4
954.8
10.5
45
61
17546
1.2
14.0023
2.9
1.6260
5.3
0.1651
4.5
0.83
985.2
40.7
980.3
33.6
969.3
60.1
969.3
60.1
46
616
154448
4.4
13.9353
1.2
1.6231
1.8
0.1640
1.4
0.75
979.2
12.5
979.2
11.5
979.1
24.5
979.1
24.5
47
692
155309
28.6
13.9340
2.8
1.6200
3.2
0.1637
1.6
0.50
977.4
14.4
978.0
20.2
979.3
56.8
979.3
56.8
(continued)
fld025-01 1st pgs page 11 Sierra de Catorce
11
TABLE 2. DETRITAL ZIRCON AGES FOR A SAMPLE FROM LA JOYA FORMATION, REAL DE CATORCE AREA (continued) Apparent ages Isotope ratios 206 206 (Ma) U ± ± Error Best age Pb/ Pb*/ U/Th 207 204 207 206 206 207 206 ppm Pb Pb* % (Ma) ± ± ± ± Pb*/ Pb*/ (%) corr. Pb*/ Pb*/ Pb*/ 235 238 238 235 207 U* % U U* (Ma) U (Ma) Pb* (Ma) 49
186
34213
50
302
79408
51
229
54282
52
166
47282
53
92
25092
54
153
19016
55
101
56
114
57
1.6
13.7837
2.2
1.6766
2.6
2.5
13.7106
1.9
1.6899
2.2
1.9
13.6443
1.0
1.7970
1.4
8.7
13.5813
2.1
1.8322
3.2
2.7
13.5206
3.0
1.8002
3.3
1.3
13.4709
2.3
1.6292
6.0
19600
2.7
13.4700
1.5
1.7517
20850
7.8
13.4465
3.1
1.6288
290
43337
2.9
13.4290
2.5
58
129
41059
4.7
13.3029
59
198
21725
1.1
13.2460
60
256
31147
1.8
13.1684
61
860
182539
3.1
13.1266
62
356
80693
3.3
13.1198
0.1676
1.4
0.54
998.9
12.9
0.1680
1.1
0.50
1001.3
0.1778
1.0
0.71
1055.1
0.1805
2.4
0.76
1069.6
0.1765
1.3
0.40
1048.0
0.1592
5.5
0.92
952.2
1.9
0.1711
1.2
0.62
4.2
0.1588
2.9
0.69
1.7898
2.8
0.1743
1.2
1.3
1.8636
1.8
0.1798
1.6
1.9416
1.9
0.1865
2.6
1.9299
2.8
0.1843
1.0
0.37
2.3
1.8945
2.9
0.1804
1.9
0.64
4.1
1.7857
4.2
0.1699
1.0
0.24
1011.6
43.9
1001.4
± Ma
999.7
16.4
1001.4
43.9
10.2
1004.7
14.2
1012.2
39.1
1012.2
39.1
9.7
1044.4
9.2
1022.0
20.3
1022.0
20.3
24.0
1057.1
21.1
1031.3
42.1
1031.3
42.1
12.8
1045.5
21.7
1040.4
61.5
1040.4
61.5
48.7
981.6
37.5
1047.8
46.2
1047.8
46.2
1018.3
11.0
1027.8
12.1
1048.0
29.5
1048.0
29.5
950.4
25.6
981.4
26.6
1051.5
62.1
1051.5
62.1
0.42
1035.9
11.3
1041.7
18.2
1054.1
51.2
1054.1
51.2
1.2
0.68
1065.9
11.8
1068.3
11.7
1073.1
26.3
1073.1
26.3
1.0
0.52
1102.6
10.1
1095.6
12.8
1081.7
32.7
1081.7
32.7
1090.5
10.4
1091.5
18.6
1093.4
51.7
1093.4
51.7
1069.0
18.3
1079.2
19.5
1099.8
45.2
1099.8
45.2
9.4
1040.3
27.4
1100.9
81.8
1100.9
81.8
63
30
9716
4.9
13.0294
3.4
1.7347
3.9
0.1639
2.0
0.51
978.6
17.9
1021.5
25.1
1114.7
67.1
1114.7
67.1
64
196
60876
4.8
13.0247
2.1
1.8489
2.6
0.1747
1.5
0.58
1037.7
14.4
1063.0
17.0
1115.4
41.9
1115.4
41.9
65
41
12922
1.4
13.0224
5.2
2.0218
5.9
0.1910
2.8
0.47
1126.6
28.5
1122.9
40.0
1115.7
103.7
1115.7
103.7
66
756
147217
6.1
12.9750
4.4
1.6605
8.6
0.1563
7.5
0.86
936.0
65.0
993.6
54.8
1123.0
87.2
1123.0
87.2
67
312
83167
2.0
12.9050
1.4
1.9861
2.9
0.1859
2.5
0.87
1099.0
25.2
1110.8
19.4
1133.8
28.3
1133.8
28.3
68
415
135513
5.3
12.7241
1.8
2.1584
2.3
0.1992
1.5
0.64
1171.0
15.7
1167.8
16.0
1161.8
35.3
1161.8
35.3
69
180
59269
2.7
12.6976
1.1
2.1804
1.5
0.2008
1.0
0.69
1179.6
10.8
1174.8
10.1
1166.0
20.8
1166.0
20.8
70
145
55307
3.3
12.6870
2.0
2.1627
2.2
0.1990
1.0
0.45
1170.0
10.7
1169.1
15.5
1167.6
39.4
1167.6
39.4
71
95
21378
2.6
12.6815
2.8
2.0719
3.0
0.1906
1.1
0.37
1124.4
11.7
1139.6
20.7
1168.5
55.5
1168.5
55.5
72
433
84991
3.3
12.6709
1.0
2.0006
3.4
0.1839
3.2
0.96
1088.0
32.4
1115.7
23.0
1170.1
19.8
1170.1
19.8
73
65
14067
5.1
12.6044
5.3
2.0460
6.0
0.1870
2.7
0.44
1105.3
26.9
1130.9
40.7
1180.5 105.6
1180.5
105.6
74
116
42693
3.5
12.5895
2.4
2.0647
4.4
0.1885
3.7
0.84
1113.4
37.6
1137.2
30.0
1182.9
47.1
1182.9
47.1
75
221
28805
2.3
12.5892
4.1
1.9521
5.9
0.1782
4.2
0.72
1057.4
41.2
1099.2
39.6
1182.9
81.3
1182.9
81.3
76
534
138404
5.5
12.5053
3.2
1.8247
5.0
0.1655
3.9
0.78
987.3
36.0
1054.4
33.0
1196.1
62.1
1196.1
62.1
77
121
34297
2.7
12.4711
1.3
2.1364
2.3
0.1932
1.9
0.83
1138.9
19.7
1160.7
15.8
1201.5
25.3
1201.5
25.3
78
103
21756
2.8
12.4551
1.8
2.2532
2.3
0.2035
1.4
0.60
1194.3
14.9
1197.8
16.1
1204.1
36.1
1204.1
36.1
79
58
17696
2.3
12.4447
3.9
2.2456
5.1
0.2027
3.3
0.64
1189.7
35.9
1195.4
36.0
1205.7
77.3
1205.7
77.3
80
556
52070
19.3
12.4038
2.6
2.1088
3.2
0.1897
1.9
0.58
1119.8
19.1
1151.7
22.0
1212.2
51.0
1212.2
51.0
81
147
72678
3.6
12.2902
1.1
2.3837
1.5
0.2125
1.0
0.67
1242.0
11.3
1237.7
10.7
1230.3
21.8
1230.3
21.8
82
333
89404
3.3
12.2889
2.3
2.3293
2.8
0.2076
1.6
0.58
1216.0
18.1
1221.3
20.1
1230.5
45.3
1230.5
45.3
83
282
84172
2.7
12.2385
1.7
2.4600
2.7
0.2184
2.1
0.77
1273.2
23.8
1260.4
19.3
1238.6
33.3
1238.6
33.3
84
171
37611
2.1
12.1875
1.1
2.4278
2.6
0.2146
2.3
0.90
1253.3
26.3
1250.9
18.5
1246.7
22.1
1246.7
22.1
85
381
99414
2.6
12.1005
2.2
2.4812
3.6
0.2178
2.9
0.80
1270.0
32.9
1266.6
25.9
1260.7
42.4
1260.7
42.4
86
81
3742
2.5
11.8179
2.4
2.0238
2.9
0.1735
1.6
0.56
1031.2
15.3
1123.5
19.5
1306.8
46.1
1306.8
46.1
87
198
65898
1.3
11.7905
1.9
2.6382
2.3
0.2256
1.2
0.55
1311.4
14.7
1311.4
16.7
1311.3
36.9
1311.3
36.9
88
145
55787
1.8
11.7181
2.1
2.7817
2.4
0.2364
1.2
0.51
1368.0
15.0
1350.6
17.8
1323.2
39.7
1323.2
39.7
89
246
85358
2.6
11.6508
1.3
2.7740
1.8
0.2344
1.3
0.69
1357.5
15.4
1348.6
13.6
1334.4
25.3
1334.4
25.3
90
590
139706
3.0
11.5709
1.6
2.7869
2.1
0.2339
1.3
0.63
1354.8
15.9
1352.0
15.3
1347.7
30.7
1347.7
30.7
91
54
16300
5.4
11.4981
2.8
2.6194
3.2
0.2184
1.5
0.48
1273.6
17.6
1306.1
23.2
1359.8
53.4
1359.8
53.4
92
151
59990
2.6
10.6641
2.3
3.3796
2.6
0.2614
1.2
0.45
1496.9
15.9
1499.7
20.5
1503.5
44.0
1503.5
44.0
93
197
75012
1.9
9.7939
2.1
3.8152
2.6
0.2710
1.6
0.60
1545.9
21.4
1596.0
20.8
1662.7
38.1
1662.7
38.1
94
431
131079
2.3
9.7750
1.0
4.0892
2.5
0.2899
2.3
0.92
1641.0
33.3
1652.2
20.5
1666.3
18.5
1666.3
18.5
95
225
54436
2.4
7.5945
1.5
4.9690
9.6
0.2737
9.4
0.99
1559.5 130.6 1814.1
80.9
2120.4
26.8
2120.4
26.8
Note: Analysis performed in the LaserChron Center, Arizona, following procedures of Gehrels et al. (2006). Coordinates: 306190 2625120.
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Barboza-Gudiño et al.
16 255 Ma
14
12
10
8
6
1056 Ma 166 Ma 1186 Ma
4
2
0 0
400
800
1200
1600
2000
2400
2800
Ma data-point error ellipses are 68.3% conf ζ
0.4
1800 0.3
238U/206 Pb
1400 0.2
1000
600
0.1
0.0 0
2
4 207
6
8
Pb/235 U
Figure 9. Detrital zircon plots as relative probability curve and histogram (A) and U/Pb concordiadiagrams for the analyzed sample (2σ error ellipses) (B), obtained from a sample from La Joya Formation, collected in the Sierra de Catorce (see data and coordinates in Table 2).
fld025-01 1st pgs page 13 Sierra de Catorce 176 Ma a rather late Toarcian age on the basis of a lower concordia intercept (Barboza-Gudiño et al., 2004). Stop 2.4. Transect along the “Upper” Cañón General (“La Purisima-Real de Catorce”) (306838 2621719) At the point known as La Purisima, on the road from Estación Catorce to Real de Catorce, the base of a sequence of pyroclastic rocks of rhyolitic composition rests on red sandstones to mudstones, greenstones and quarzites of the Lower Jurassic marine marginal facies known as “Cerro El Mazo beds” (Barboza-Gudiño et al., 2004; Venegas-Rodríguez et al., 2009). Maher et al. (1991), Bartolini et al. (1999), and McKee et al. (1999) reported plant fossils from this unit that suggests an Early Jurassic age. The pyroclastic rocks consist of airfall deposits or laminated ash, unwelded tuff with volcanic breccia horizons and marked pseudostratification at the base, grading upsection into massive deposits, showing several intensely sheared zones containing sericite as a result of dynamic metamorphism and associated hydrothermal alteration. Basaltic-andesitic lava also occurs in the volcanic succession exposed in the Sierra de Catorce. The lava contains fluidal porphyritic texture with highly altered, probable hornblende phenocrysts, scarce pyroxene, olivine, and plagioclase in a fine groundmass composed of acicular plagioclase, ferromagnesian minerals, and opaque grains. Some lavas are brecciated. Similar basaltic-andesitic lavas crop out at Sierra de Salinas and Sierra de Charcas. The volcanic units are unconformably overlain by Middle to Upper Jurassic redbeds of La Joya Formation. The exposed succession along this trip forms part of the eastern flank of an uplifted structure known as the “Los Catorce Antiform.” DAY 3 Stop 3.1. Trip along the “Lower” Cañón General (Los Catorce) (303145 2621843) The field trip follows the road from Real de Catorce to Cedral for 14 km and then the highway to Vanegas, where it crosses the Mexico-Laredo railroad; from there, a paved road parallel to the tracks leads to Estacion Catorce, and to the east a dirt road leads into the lower part of Cañon General of Sierra de Catorce. Along this part of the canyon the western flank of the Los Catorce Antiform is exposed, in the northwestern Sierra de Catorce uplift. Along the road to Los Catorce from the small town of Carretas, there are excellent exposures of the mid-Cretaceous (AlbianCenomanian) Cuesta del Cura and Tamaulipas Superior formations. These units are characterized by medium- to thin-bedded limestone with black chert bands and nodules. They were deposited in the Mexican Sea, west of the Valles–San Luis platform. To the west along the same road, the Lower Cretaceous units are also exposed; these occur as thin- to medium-bedded limestone
13
with interbedded thin shale horizons of the Taraises Formation (Berriasian-Valanginian), thick-bedded micritic limestone with brown-gray chert nodules of the Tamaulipas Inferior Formation (Barremian), and thin-bedded limestone and marls of La Peña Formation (Aptian). Figure 3 shows the complete stratigraphic column of Sierra Catorce and a brief lithologic description of the units exposed (after Barboza-Gudiño and Torres-Hernández, 1999, and Barboza-Gudiño et al., 2004). For comparison, Figure 10 shows a general correlation table of the Sierra de Catorce stratigraphy with the Mesozoic stratigraphy of other localities in northern Mexico and southeastern United States. Stop 3.2. Cerro El Mazo (304502 2622356) Two km west of the town of Los Catorce, along the road from this town to Carretas, the Upper Jurassic is represented by marls, shaly limestone, and uncommon interlayered sandstone of the La Caja Formation (Kimmeridgian-Berriasian) overlying thick-bedded limestone of the Zuloaga Formation (Oxfordian). The Zuloaga Formation gradationally overlies redbeds of the La Joya Formation, which constitute an upward-fining succession of more than 250 m that includes breccias and conglomerates at the base, grading upward into red sandstone, with a dominantly fine sequence of siltstone and claystone at the top. The transition between mudstones of La Joya into limestone of the Zuloaga Formation is characterized by thin evaporite interbeds and progressively more abundant limestone. However, this interval contains numerous detachment surfaces where the limestone of the basal Zuloaga Formation is commonly mylonitized. This is expressed as a foliated white fault rock with a very fine SC fabric, which is visible only in thin section. In the west flank of the Los Catorce Antiform, the volcanic succession of the Nazas Formation is markedly diminished to a few meters of red-purple, possibly epiclastic deposits, which are similar to interlayered horizons within the volcanic succession that occur in the eastern flank of the same structure. The Lower Jurassic succession here includes the “Cerro El Mazo beds” unit, consisting of quartzite and litharenite and interlayered red and yellow mudstone (Fig. 11), and containing remains of plants (probably Cycadeoids) as well as basaltic-andesitic greenstones both as dikes or sills and lava flows, the products of synsedimentary volcanic activity. The Cerro El Mazo beds are interpreted as shallow marine and marginal facies. This unit of the Sierra de Catorce is comparable in age with Lower Jurassic strata cropping out near El Alamito, west of Rioverde, 200 km SE of Catorce, and with strata of the Huayacocotla Formation in Hidalgo and Veracruz. Cerro El Mazo beds may be also correlative with Lower Jurassic strata of the Santa Rosa Formation of Sonora (González León et al., 2009). An initial report of the probable existence of Lower Jurassic strata in the Sierra de Catorce, based on the presence of the ammonites Vermiceras sp. and Arnioceras cf. Abjectum Fucini n. subsp., has remained in doubt since 1956 because of uncertainty
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Cretaceous
regarding the precise location of the outcrop and a lack of subsequent reports of fossils. However, detrital zircon geochronology on coarse-grained litharenites from the Cerro El Mazo beds (Venegas-Rodríguez et al., 2009) yielded a Late Triassic–Early Jurassic maximum depositional age on the basis of the youngest zircon grains in the sample (age of youngest zircons here), as well as three possible basement sources of zircons that include Grenvillian (ca. 900–1200 Ma), Pan-African (ca. 500–700 Ma) and
Maastrichtian Campanian Santonian Coniacian Turonian Cenomanian Albian Aptian Barremian Hauterivian Valanginian Berriasian Tithonian
Sierra de Catorce
Galeana, N.L.
La Boca canyon
Texas
Caracol/Mendez
Mendez
Mendez
Navarro Taylor
Indidura
San Felipe
San Felipe
Austin
Agua Nueva Agua Nueva Cuesta del Cura Cuesta del Cura Cuesta del Cura Tamaulipas sup. Tamaulipas sup. Tamaulipas sup. La Peña (Otates) La Peña (Otates) La Peña (Otates)
Jurassic
Trinity Pearsall
Tamaulipas inf.
Sligo
Taraises
Taraises
Taraises
Hosston Sycamore
La Caja
La Casita
La Casita
Cotton Valley
Olvido
Buckner Smackover
Zuloaga
Zuloaga Olvido Minas Viejas
Caliza Novillo
La Joya
La Joya
La Joya
Bathonian Bajocian Aalenian Toarcian
Nazas
La Boca
Pliensbachian Sinemurian Hettangian Rhaetian
Triassic
Fredericksburg
Tamaulipas inf.
Callovian
Norian Carnian
Eagle Ford Woodbine-Buda
Tamaulipas inf.
Kimmeridgian Oxfordian
the Permo-Triassic magmatic arc (ca. 245–280 Ma). The interlayered mafic rocks likely record the onset of Jurassic volcanic arc activity, but it is also possible that this earliest Jurassic mafic magmatism is not related to the Nazas arc. This is because there are several differences in the geochemistry of these rocks. The chemistry of Cerro El Mazo volcanic rocks is typical of poorly evolved magmatic rocks, and their petrographic features are more characteristic of spilitic rocks. However, these rocks are indicative
Zacatecas
El Alamar
El Alamar
Ladinian Anisian Scythian Figure 10. Correlation chart for northeastern Mexico and southeastern Texas.
LouannWerner
fld025-01 1st pgs page 15 Sierra de Catorce
15
Figure 11. Aspect of the Lower Jurassic Cerro El Mazo beds, near Los Catorce, Sierra de Catorce. This succession consists of sandstones or litharenites (Sst.) and quarzites (Qz.), red purple to yellow-green siltstone and shale (Sh.), alternating with several basaltic-andesitic lava flows (greenstones, Gst.); sills and dikes also are present in the area.
of subduction volcanism (Rodríguez-Hernández, 2009). On the basis of our observations, we conclude that marginal marine strata of Cerro El Mazo in the Sierra de Catorce (post-Norian to pre-Bajocian?) were probably deposited along the paleo-Pacific margin of Mexico during the Early Jurassic in a forearc setting.
Triassic age of deposition for this succession. The facies associations in Triassic strata in Real de Catorce are comparable with those of the Charcas exposures visited in Day 1, but finer grained rocks dominate the section at Real de Catorce. These are interpreted as inter-channel deposits (lithofaces “D,” “E,” and “G”), and subordinate suprafan, levee, and channel deposits (Fig. 12).
Stop 3.3. Los Catorce: Late Triassic Turbidite Succession (305484 2622469)
DISCUSSION AND CONCLUSIONS
The Zacatecas Formation in Sierra de Catorce consists of finely laminated shale and intercalated thin siltstone and sandstone layers. The exposures at Cañón General, around the village of Los Catorce represent the most extensive exposures of Triassic rocks in the Sierra de Catorce. In addition, there are outcrops of comparable strata in Cañon Ojo de Agua or “El Salto” to the north and the southern Sierra de Catorce in El Astillero canyon. A Late Triassic age for the succession is inferred from lithologic similarities with fossil-bearing strata at other localities and their stratigraphic position; there are no reports of Triassic fossils in this locality. An older age has been suggested by a possible late Paleozoic flora (Franco-Rubio, 1999) and late Paleozoic spores (Bacon, 1978), but recently published detrital zircon geochronology (Fig. 6; Barboza-Gudiño et al., 2010) and geochronological data obtained from Jurassic volcanic rocks in the Sierra de Catorce (Barboza-Gudiño et al., 2004) are consistent with a Late
One of the most relevant aspects of the Mesozoic evolution of the Mexican subcontinent is a continuous stratigraphic record of plate convergence along its Pacific margin (e.g., Dickinson and Lawton, 2001; Sedlock et al., 1993). Convergence has been related to subduction of the Farallon plate. Stratigraphic units in several uplifted structural complexes in north-central and northeastern Mexico indicate repeated tectonic-magmatism cycles from Permian to Cretaceous, corresponding to sedimentation, magmatism and deformation in subduction settings (Fig. 13). The geologic record of subduction in Mexico during that time is complex, but in general there is a westward younging trend in the locus of magmatism. Each cycle of sedimentation, magmatism, and deformation is displaced progressively more than 500 km westward from the Permian paleo-Pacific margin of Pangea, whose remnants are located today in eastern Mexico up to the present Pacific margin.
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Figure 12. Triassic turbiditic sequence exposed by Los Catorce, Cañon general, Sierra de Catorce.
Nascent Guerrero Terrane
subduction Late Jurassic-Cretaceous Nazas Arc
Early to Middle Jurassic Low stress subduction
Deformation of the Potosi Fan
Late Triassic El Alamar Formation
Latest Triassic-Early Jurassic
Figure 13. Model of the tectonic evolution of the ancient western margin of Pangea, during the Late Paleozoic– Early Mesozoic.
high stress subduction Potosi Fan Late Triassic
Permian-Triassic Low stress subduction
Permo-Triassic Arc
WSW
ENE metamorphism of Granjeno shist
Carboniferous-Permian
high stress subduction
Oaxaquia
fld025-01 1st pgs page 17 Sierra de Catorce At several localities of the Mesa Central province, Upper Triassic strata of the Zacatecas Formation and its correlatives, which form the record of the “Potosí submarine Fan,” are strongly deformed and locally exhibit low-grade metamorphism. Lithofacies assemblages have locally been interpreted as the record of a subduction complex (Anderson et al., 2005; Dávila-Alcocer et al., 2008), suggesting that a subduction zone was active in a high-stress stage during the latest Triassic time, producing deformation and uplift of Zacatecas Formation strata. Whereas Centeno-García (2005) suggested that the fan was formerly located to the northwest and was displaced to its present position by the hypothetical Mojave-Sonora megashear, the detrital zircon geochronology of this unit is consistent with an autochthonous or para-autochthonous setting. Widespread arc-volcanism occurred during a subsequent low-stress stage of subduction. Predominantly subaerial volcanic deposits of the Nazas Formation rest on deformed marine Triassic rocks in the states of Zacatecas and San Luis Potosí, and on continental Triassic strata or older rocks in Nuevo León and Tamaulipas (Barboza-Gudiño et al., 2008, 2010; Rubio-Cisneros and Lawton, 2011). Whereas previous authors (e.g., Jones et al., 1995) have suggested that volcanic rocks of the Nazas Arc are a displaced fragment of the Sonora Cordilleran Arc, transported to the southeast by the Mojave-Sonora megashear, the fact that the continuity of outcrops of Jurassic volcanic rocks on both sides of the inferred megashear trace from Sonora (Rancho Basomari Formation of Mauel et al., 2011), through Chihuahua, into San Luis Potosí, Nuevo León, and Tamaulipas suggests that a NW-trending paired arc-trench system was continuous across northern Mexico. The remnants of the Paleozoic Pangean continent located to the east and represented by the Proterozoic Novillo Gneiss and Granjeno Schist that yields late Paleozoic metamorphic ages are exposed in Tamaulipas and Nuevo León. El Alamar Formation (BarbozaGudiño et al., 2010), initially considered as part of La Boca Formation (Mixon et al., 1959), is an Upper Triassic fluvial succession which crops out in El Alamar Canyon and in the San Marcos area, south of Galeana, Nuevo León, as well as in the northern part of the Huizachal Peregrina Anticlinorium in Tamaulipas. These continental strata are interpreted as the headwaters of the Potosí Fan. La Boca Formation, unconformably overlain by the Middle to Upper Jurassic La Joya Formation in the Sierra Madre Oriental, includes interlayered volcanic rocks and epiclastic strata, comparable in age with the Nazas Formation of the Mesa Central, and is now considered part of the Early Jurassic volcanic arc of eastern Mexico (Rubio-Cisneros and Lawton, 2011). GodínezUrban et al. (2011) have suggested that arc volcanism continued east into the Chiapas massif which lay reconstructed east of the Tamaulipas outcrops of La Boca Formation prior to the opening of the Gulf of Mexico (Molina-Garza et al., 1992). Available observations and data from northeastern Mexico, as well the areas to be visited during this field trip, indicate that the Triassic to Lower Jurassic stratigraphic units present in the Sierra de Catorce, and in several localities in western San Luis Potosí and Zacatecas, can be considered remnants of the paleo-
17
Pacific margin of western Pangea during early Mesozoic times. West of this ancient margin, parts of the sedimentary pile of the voluminous Potosí Fan were likely deposited on the continental slope and the adjacent oceanic crust and carried eastward into the active trench. During the Late Jurassic and Early Cretaceous, the intraoceanic volcanic activity of the Guerrero terrane was initiated, followed in the Late Cretaceous by the consolidation of most of the actual Mexican subcontinent. ACKNOWLEDGMENTS We acknowledge constructive reviews and suggestions by Ana Bertha Villaseñor and Federico Olóriz. REFERENCES CITED Anderson, T.H., Jones, N.W., and McKee, J.W., 2005, The Taray Formation: Jurassic(?) mélange in northern Mexico—Tectonic implications, in Anderson T.H., Nourse, J.A., McKee, J.W., and Steiner, M.B., eds., The Mojave-Sonora Megashear hypothesis: Development, assessment and alternatives: Geological Society of America Special Paper 393, p. 427– 455, doi:10.1130/0-8137-2393-0.427. Bacon, R.W., 1978, Geology of the northern Sierra de Catorce, San Luis Potosí, México [master’s thesis]: Arlington, University of Texas, 124 p. Baker, C.L., 1922, General geology of the Catorce mining district: Transactions of the American Institute of Mining and Metallurgical Engineers, v. 66, p. 42–48. Barboza-Gudiño, J.R., 1989, Geologische Kartierung (1:10 000) des Gebietes “Cañón General,” Sierra de Catorce, San Luis Potosí, México—mit besonderer Berücksichtigung des prä-oberjurassichen Gründgebirges (Diplomarbeit): Technische Universität Clausthal, Germany, 107 p. Barboza-Gudiño, J.R., and Torres-Hernández, J.R., 1999, Carta geológicominera Real de Catorce (F14–A24), escala 1:50 000: México, Consejo de Recursos Minerales, SECOFI, 1 mapa y texto explicativo. Barboza-Gudiño, J.R., Tristan-Gónzalez, M., and Torres-Hernández, J.R., 1999, Tectonic setting of pre-Oxfordian units from central and northeastern Mexico: A Review, in Bartolini, C., Wilson, J.L., and Lawton, T.F., eds., Mesozoic Sedimentary and Tectonic History of North-Central Mexico: Geological Society of America Special Paper 340, p. 197–210, doi:10.1130/0-8137-2340-X.197. Barboza-Gudiño, J.R., Hoppe, M., Gómez-Anguiano, M., and Martínez-Macías, P.R., 2004, Aportaciones para la interpretación estratigráfica y estructural de la porción noroccidental de la Sierra de Catorce, San Luis Potosí, México: Revista Mexicana de Ciencias Geológicas, v. 21, p. 299–319. Barboza-Gudiño, J.R., Orozco-Esquivel, M.T., Gómez-Anguiano, M., and Zavala-Monsiváis, A., 2008, The Early Mesozoic volcanic arc of western North America in northeastern Mexico: Journal of South American Earth Sciences, v. 25, p. 49–63, doi:10.1016/j.jsames.2007.08.003. Barboza-Gudiño, J.R., Zavala-Monsiváis, A., Venegas-Rodriguez, G., and Barajas-Nigoche, L.D., 2010, Late Triassic stratigraphy and facies from northeastern Mexico: Tectonic setting and provenance: Geosphere, v. 6, no. 5, p. 621–640, doi:10.1130/GES00545.1. Bartolini, C., and Spell, T., 1997, An Early Jurassic age (40Ar/39Ar) for the Nazas Formation at the Canñada Villa Juárez, northeastern Durango, México: Geological Society of America Abstracts with Programs, v. 29, no. 2, p. 3. Bartolini, C., Lang, H., and Stinnesbeck, W., 1999, Volcanic rock outcrops in Nuevo León, Tamaulipas and San Luis Potosí, México: Remnants of the Permian–Early Triassic magmatic arc? in Bartolini, C., Wilson, J.L., and Lawton, T.F., eds., Mesozoic sedimentary and tectonic history of NorthCentral Mexico: Geological Society of America, Special Paper 340, p. 347–356, doi:10.1130/0-8137-2340-X.347. Cantú-Chapa, A., 1969, Una nueva localidad del Triásico Superior marino en México: Instituto Mexicano del Petróleo, Revista, v. 1, p. 71–72. Castillo, A., del, and Aguilera-Serrano J.G., 1895, Fauna fósil de la Sierra de Catorce, San Luis Potosí: Comisión Geológica de México, Boletín n. 1, 55 p., 24 láminas. Centeno-García, E., 2005, Review of Upper Paleozoic and Mesozoic stratigraphy and depositional environments of central and west Mexico:
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