Loma_Gorda_Formation

Loma Gorda Formation

Loma Gorda Formation

Geological formation in the Colombian Andes

The Loma Gorda Formation (Spanish: Formación Loma Gorda, Kl, Kslg) is a fossiliferous geological formation of the Upper Magdalena Valley (VSM) and surrounding Central and Eastern Ranges of the Colombian Andes, extending from Cundinamarca in the north to Huila and easternmost Tolima in the south. The uppermost unit of the Güagüaquí Group, a sequence of laminated siltstones and shales, dates to the Late Cretaceous period; Turonian to Coniacian epochs, and has a maximum thickness of 167 metres (548 ft).

Quick Facts Type, Unit of ...

Etymology

The formation was named in 1966 by De Porta, named Loma Gorda ("Fat Hill") in Ricaurte, Cundinamarca.[1]

Description

Lithologies

The Loma Gorda Formation is characterised by laminated siltstones and shales with calcareous concretions.[2] The formation has provided fossils of Ankinatsytes venezolanus, Barroisiceras onilahyense, Codazziceras ospinae, Eulophoceras jacobi, Fagesia catinus, Hauericeras madagascarensis, Hoplitoides ingens, H. lagiraldae, Mitonia gracilis, Mytiloides kossmati, M. goppelnensis, M. scupini, Neoptychites cf. andinus, Paralenticeras sieversi, Paramammites sp., Peroniceras subtricarinatum, Prionocycloceras guayabanum, Reesidites subtuberculatum, Subprionotropis colombianus, Allocrioceras sp., Anagaudryceras sp., Anomia sp., Benueites sp., Choffaticeras sp., Dydimotis sp., Forresteria sp., Gauthiericeras sp., Morrowites sp., Nannovascoceras sp., and Quitmaniceras sp..[3]

Stratigraphy and depositional environment

The Loma Gorda Formation is the uppermost unit of the Güagüaquí Group.[1] It overlies the Hondita Formation and is overlain by the Oliní Group. The age has been estimated on the basis of ammonites to be ranging from Turonian to Coniacian.[2] Stratigraphically, the formation is time equivalent with the upper parts of the Chipaque, La Luna and La Frontera Formations.[4] The formation was deposited in a relative highstand sequence with an oceanic oxygen depletion event, sharply marked in Colombia and characterised by the appearance of calcareous concretions with a thick pyrite rim.[5]

Outcrops

Loma Gorda Formation
Type locality of the Loma Gorda Formation to the southwest of the Altiplano Cundiboyacense

The type locality of the Loma Gorda Formation is located close to Loma Gorda in Ricaurte, Cundinamarca.[6] Other outcrops of the Loma Gorda Formation have been noted east of the Magdalena River northeast of Honda,[7] west of Nariño,[8] west across the Magdalena River in San Luis, Tolima,[9] between the Tetuán and Saldaña Rivers west of Coyaima and east and west of Ataco,[10] to the east of the Prado River reservoir,[11] north and west of Aipe,[12] surrounding Alpujarra, Tolima,[13] south of Palermo, Huila, displaced by the Baché Fault,[14] east of Iquira,[15] north of Yaguará,[16] south of La Plata where the formation is cut by the Itaibe Fault,[17] a small patch east of Gigante, Huila,[18] northwest and northeast of San Agustín,[19] and north of Timaná surrounding the Magdalena River.[20]

Regional correlations

More information Ma, Age ...
Legend
  • group
  • important formation
  • fossiliferous formation
  • minor formation
  • (age in Ma)
  • proximal Llanos (Medina)[note 1]
  • distal Llanos (Saltarin 1A well)[note 2]

See also

Geology of the Eastern Hills
Geology of the Ocetá Páramo
Geology of the Altiplano Cundiboyacense
Geology of the Middle Magdalena Valley

Notes

  1. [N 1]
    based on Duarte et al. (2019)[57], García González et al. (2009),[58] and geological report of Villavicencio[59]
  2. [N 2]
    based on Duarte et al. (2019)[57] and the hydrocarbon potential evaluation performed by the UIS and ANH in 2009[60]

References

  1. [1]
    Acosta & Ulloa, 2002, p.23
  2. [2]
    Acosta & Ulloa, 2002, p.24
  3. [3]
    Patarroyo, 2011
  4. [4]
    Acosta & Ulloa, 2002, p.22
  5. [5]
    Villamil, 2012, p.173
  6. [6]
    Acosta & Ulloa, 2001, p.43
  7. [7]
    Plancha 207, 2010
  8. [8]
    Plancha 245, 1999
  9. [9]
    Plancha 264, 2002
  10. [10]
    Plancha 282, 1993
  11. [11]
    Plancha 283, 2009
  12. [12]
    Plancha 302, 1993
  13. [13]
    Plancha 303, 2002
  14. [14]
    Plancha 323, 1998
  15. [15]
    Plancha 344, 1999
  16. [16]
    Plancha 345, 1999
  17. [17]
    Plancha 366, 1998
  18. [18]
    Plancha 367, 2003
  19. [19]
    Plancha 388, 2002
  20. [20]
    Plancha 389, 2003
  21. [21]
    García González et al., 2009, p.27
  22. [22]
    García González et al., 2009, p.50
  23. [23]
    García González et al., 2009, p.85
  24. [24]
    Barrero et al., 2007, p.60
  25. [25]
    Barrero et al., 2007, p.58
  26. [26]
    Plancha 111, 2001, p.29
  27. [27]
    Plancha 177, 2015, p.39
  28. [28]
    Plancha 111, 2001, p.26
  29. [29]
    Plancha 111, 2001, p.24
  30. [30]
    Plancha 111, 2001, p.23
  31. [31]
    Pulido & Gómez, 2001, p.32
  32. [32]
    Pulido & Gómez, 2001, p.30
  33. [33]
    Pulido & Gómez, 2001, pp.21-26
  34. [34]
    Pulido & Gómez, 2001, p.28
  35. [35]
    Correa Martínez et al., 2019, p.49
  36. [36]
    Plancha 303, 2002, p.27
  37. [37]
    Terraza et al., 2008, p.22
  38. [38]
    Plancha 229, 2015, pp.46-55
  39. [39]
    Plancha 303, 2002, p.26
  40. [40]
    Moreno Sánchez et al., 2009, p.53
  41. [41]
    Mantilla Figueroa et al., 2015, p.43
  42. [42]
    Manosalva Sánchez et al., 2017, p.84
  43. [43]
    Plancha 303, 2002, p.24
  44. [44]
    Mantilla Figueroa et al., 2015, p.42
  45. [45]
    Arango Mejía et al., 2012, p.25
  46. [46]
    Plancha 350, 2011, p.49
  47. [47]
    Pulido & Gómez, 2001, pp.17-21
  48. [48]
    Plancha 111, 2001, p.13
  49. [49]
    Plancha 303, 2002, p.23
  50. [50]
    Plancha 348, 2015, p.38
  51. [51]
    Planchas 367-414, 2003, p.35
  52. [52]
    Toro Toro et al., 2014, p.22
  53. [53]
    Plancha 303, 2002, p.21
  54. [54]
    Bonilla et al., 2016, p.19
  55. [55]
    Gómez Tapias et al., 2015, p.209
  56. [56]
    Bonilla et al., 2016, p.22
  57. [57]
    Duarte et al., 2019
  58. [58]
    García González et al., 2009
  59. [59]
    Pulido & Gómez, 2001
  60. [60]
    García González et al., 2009, p.60

Bibliography

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