Basin development and tectonic history of the Middle Magdalena Valley Nomenclatura estándar del Standard Nomenclature for Middle ISC 2018 Valle Medio del Magdalena - Magdalena Valley - Colombia ICS - IUGS Colombia, Servicio Geológico L.G. Morales et al., 1958 Colombiano, 2019 66 Maastrichtiano Formación Umir 72 Umir Shale Campaniano Formación La Renta 84 Santoniano 86 Galembo Member Formación Galembo Coniaciano La Luna 90 Fm. Pujamana Member Formación Pujamana Turoniano Formación Salada Salada Member 94 Cenomaniano Formación El Salto Salto Limestone 100 Formación Simití Albiano Simití Shale Fm. Tablazo 113 Tablazo Limestone Basal Formación La Paja L i Aptiano m e Paja Formation s t 125 o n Barremiano e Rosa Blanca Fm. 129 Gr. Hauteriviano 133 Valanginiano Formación Rosa Blanca Tambor Formation 140 Berriasiano Formación Cumbre 145 Formación Los Santos “Howewer, as our studies continue, more and more concealed breaks become apparent” Dereck Victor Ager Portadilla: Standard nomenclature for the Middle Magdalena Valley adopted by the Servicio Geológico Colombiano. Citación Etayo-Serna, Fernando. 2019. “Basin development and tectonic history of the Middle Magdalena Valley”. En Estudios geológicos y paleontológicos sobre el Cretácico en la región del embalse del río Sogamoso, Valle Medio del Magdalena, dirección científica y edición de Fernando Etayo-Serna. Compilación de los Estudios Geológicos Oficiales en Colombia vol. XXIII. Bogotá: Servicio Geológico Colombiano. Basin development and tectonic history of the Middle Magdalena Valley Fernando Etayo-Serna 8 Hans Stille's work initiated tectonic studies in the basin” (Barrero et al. 2007) of late Cenozoic age Middle Magdalena Valley and introduced the word (Cáceres, Cediel and Etayo-Serna 2003) (fig. 1). graben (Hubach 1929). Years later, Harrison wro- te: “The Upper Magdalena Valley is a trough like The tectonic framework of the MMV basement in- depression or Graben (1930, 399. Notice the equi- termittently affected its stratigraphic architectu- vocal Upper) … … would recall the northern end of the Red Sea”. According modern speculations not based on any direct ob- to Harrison, this[ ] that“trench if could … brokebe flooded down [ in] early re.servation More field and informationat the same istime, necessary as advised to validate by J. T. Tertiary times” (op. cit., 408). Likewise, pre-Paleo- Wilson (1990), we should not permit “Neglect of zoic and Paleozoic rocks of[ Colombia] were named what is already known”. basement, while cover was used for rocks of Meso- zoic to Pleistocene age (Hubach 1929, after Stille INTERPLAY OF TECTONISM AND SEA 1907). The acceptance of a Tertiary age for the LEVEL CHANGES IN THE MMV DURING MMV led to the adoption of Dana's geosynclinal terminology to name the space of deposition of THE CRETACEOUS Cretaceous sediments in the MMV (Hubach 1929; Cizancourt 1933; Morales and The Colombian Pe- In a plate tectonic setting, the Middle Magdalena Va- troleum Industry 1958; Bürgl 1961; Julivert 1961). lley was generated during the “extensional stage” of a Late Triassic to Jurassic rifting episode that affec- A thorough analysis of the distribution of Creta- ted northwestern South América (Cáceres, Cediel ceous sedimentary rocks in Colombia (Etayo, Ren- and Etayo-Serna 2003) (fig. 1). The original structu- zoni and Barrero 1969, 1976) showed that these re of the MMV is that of an asymmetric rift that pro- gressively slants to the west. Proximity to the faulted (1983) reintroduced the idea of a graben, adding and raised block of the Santander Massif has caused rocksthat it didwas notactive fit sincea geosynclinal the Early Cretaceous, outline. Fabre and up and down movements of basement blocks like pia- renamed it the Magdalena-Tablazo Basin. no keys, which caused the following features. 1) An angular unconformity between Cretaceous Los San- Inasmuch as Harrison's paper was included in Sec- tion VI-Rift Valleys of the 15th International Geo- Schuchert 1935; Julivert and Téllez 1963; Cediel logical Congress in Pretoria, terms such as Edward tos1968; and Laverde Jurassic 1995; Jordán Rolón Formations and Carrero (Notestein 1995) (fig. in Suess's graben and J. W. Gregory's rift (Willis 1928) 2A). 2) A disconformity between the lower upper Va- become almost synonymous and commutative in langinian Carrizal Member and the lower Hauteri- the geological literature on Colombia (Sarmiento fig. Rojas 2001; Toro et al. 2002; Rolón 2004; Barrero 2B). 3) Condensation of middle Barremian beds and et al. 2007). viana paraconformity Zo Member ofbetween the Rosa these Blanca and theFormation upper lower ( - OVERVIEW OF THE CRETACEOUS IN rrasse and Etayo-Serna 2013) (fig. 2D). 4) A para- THE MIDDLE MAGDALENA VALLEY Aptianconformity beds between of the La the Paja cuspidal Formation beds (Gaona, of the MauRosa The Río Magdalena basin consists of three geomor- fig. 2C). 5) Progra- phically distinct sectors, each with a different geo- Blancading and Formation retrograding and basalsequences upper in lower the upperBarremian beds logical history: (1) the south sector or Upper Mag- beds of the La Paja Formationfig. (3). 6) A composite dalena Valley, extending from the riverhead to - Honda, occupies the axial domain of a Mesozoic oftion, the upper Tablazo lower Formation Albian (fig. ( 2E). 7) Beveled contact back-arc; (2) the middle sector or Middle Magdale- hardground surface at the top of the Tablazo Forma na Valley, extends from Honda to El Banco and oc- cupies the Mesozoic rifted central part of Colombia; Itbetween has been the demonstrated Simití and El Salto that Formations.“Compressional tec- and (3) the northeast lower sector, the Lower Mag- tonics … controlled the stratigraphic and structu- dalena Valley, goes from El Banco to Barranquilla ral attributes of the southern Middle Magdalena Va- and developed over a “triangular transtensional lley Basin[ ] since 70 Ma” (Gómez et al. 2003, 146). 415 Servicio Geológico Colombiano | Fernando Etayo-Serna Figure 1. Taken from: Facies distribution and tectonic setting through the Phanerozoic of Colombia (Cáceres, Cediel and Etayo-Serna 2003). 416 Capítulo 8 | MMV - Basin Development Figure 2C. Paraconformity between medial beds of the La Paja Formation (or- ganic-rich marlstone, calcareous clay shales and clay shales) of upper lower Aptian age overlying condensed middle Barremian wackestone, Curití Quarry. Photo by F. Etayo-Serna (Gaona, Maurrasse and Etayo-Serna 2013). Figure 2D. Paraconformity between cuspidal beds of the Rosa Blanca Forma- tion and basal beds of the La Paja Formation. Private road from Los Santos to El Carrancho gypsum mine. Photo by D. Montoya (see D. Montoya 2019a). Figure 2E. Composite hardground surface at top of the Tablazo Formation. Figure 2A. Angular unconformity between moderately dipping Jordán Formation Eastern side of Lebrija-San Vicente de Chucurí road, near the bridge over the beds and horizontal Los Santos Formation. Photo taken from N scarp of the Chicamo- Sogamoso River (N: 1.269.645°, E: 1.081.053°, Z: 352 m). Photo by D. Montoya cha River, Camino del Roto, looking SE. (see fig. 4). Photo by F. Etayo-Serna. (see Montoya 2019b; Immenhauser et al. 2000, fig. 11). Figure 2B. Disconformity between the upper beds of the Carrizal Member, slightly bent, and bed P at the base of the Zo Member, both of the Rosa Blanca Formation. W side of El Platanalito Creek near its confluence with the Sogamoso River. Photo by D. Montoya (Etayo- Serna and Guzmán Ospitia 2019). 417 Servicio Geológico Colombiano | Fernando Etayo-Serna Segmento VII Segmento V Figure 3A. View of segments VII to V of the Tablazo Formation. A cliff section at the junction of the highway to San Vicente de Chucurrí and the road to Betulia (Estadero El Nuevo Ramo, km 22+200). Photography by D. Montoya, taken from the southern end of the bridge over Quebrada El Ramo. Notice the increase in bed thickness downdip in a fan-like arrangement from the top of the hill toward the river level. Figure 3B. Oblique close-up picture to show the internal stratification of segment V of the Tablazo Formation. Observe the primary inclination of the bedding: sedi- ments accumulated on a tilted bottom reflecting some significant tectonic episo- Figure 3C. Outcrop of stratigraphic segment V (conjunto N2 -dark- and conjun- de, as demonstrated by the truncation at the top of both sets of beds (Ravnås and to O -light-) of the Tablazo Formation to show the fan-shaped arrangement of Steel 1998, fig. 2). Roadside outcrop in front of Estadero El Nuevo Ramo. beds. Cerro El Tablazo (D. Montoya, this book 2019b, fig. 90A). 418 Capítulo 8 | MMV - Basin Development - - quence by the occurrence of Mediterranean short-lived ammoni- racterized by the alternation of dark calcareous and argilla- Globaltes of the sea early level late rises Valanginian seem reflected Saynoceras in the MMV verrucosum stratigraphic ( se , Atceous the typemudstones section,. In the segment La Paja I,Formation calcareous (4), mudstones 290 m, is chaare 1841), the late early Barremian Nicklesia pulchella ( , predominant, with organic matter and abundant Dasyclada- 1841) and Parasaynoceras horridum ( , 1850) (Etayo-SerOrbigny- cean algae remains. Segment II has similar lithology but na 1993; 2019), and the early middle Albian OxytropidocerasOrbigny (Mi- rapelia) mirapelianum ( , 1850)Orbigny (Orbigny, 1842; Rawson and veins. Segment III consists of predominantly argilla- 1993; Etayo-Serna 1993). It must be said here that oceanic surface showsceous mudstones lenses of fibrous with organic calcite matter.