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ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES CHURUVITA GROUP (Upper Albian ? pars-Turonia!" pars?) The name "Churuvita Group" was first proposed by Etayo Serna (1968b), with the type locality a section on Quebrada Churuvita (a tributary of Rio Samaci) along the Sachica Puente Samac& highway; According to Etayo Serna, the Churuvita Group is comprised of the Churuvita Fonnation and the overlying San Rafael Fonnation. The Churuvita Fonnation was originally described by Etayo Serna (1968a) who selected as the type locality the exposures on Quebrada Churuvita along the Sachica-Puente Samaca road. In the area of interest, the Churuvita Formation forma the highest ridge on the west flank of the Arcabuco anticlinorium; it is also exposed on the limbs of the Churuvita syncline along the Sachica-Puente Samaca highway. A tripartite division of the formation is observed; (a) a basal unit consisting essentially of gray, thick-bedded, quartzose sandstones with thin interbeds of claystone and siltstone; (b) a mid· dle interval of lenticular limestone beds, sometimes argillaceous, rich in Exogyra, which alternate with claystone and siltstone as well as occasional quartzose sandstones; and (c) an upper unit comprised of massive beds of fine to medium grained sandstones and equally massive limestones interbedded with claystones and siltstones. In general the formation changes facies toward the west where it becomes more arena· ceous. The three subdivisions of the formation, from bottom to top, measure 105 meters (244 feet), 75 meters (246 feet) and 225 meters (738 feet), respectively, giving a total of 405 meters (1328 feet). The fonnation thins toward the north. Contact with the San Gil Group is con· formable at some localities and transitional at others whereas the relationship with the overl· ying San Rafael is everywhere conformable. Fauna collected from the Churuvita Formation consists for the most part of bivalve mollusks; they are not described in the present report; after Etayo Serna (1968, p.41) the mollusks are the following: Exogyra boussingaultii Dietrich (non D'Orbigny) Plicatulopecten concentricus Brtiggen Ostrea syphax Coquand? Pecten tenouklensis Coquand Exogyra squamata d'Orbigny Paleontological data from the underlying and overlying strata suggest that the unit may be assigned to the Albian pars (?)·Cemomanian. The report of Venezoliceras (?), previously (cp.cit)tentatively assigned to the base of the unit iS now considered unreliable information. SAN RAFAEL FORMATION · (Lower Turonian) Etayo Serna (1968a) first proposed the fonnation. As type locality he chose the que· brad a whose source is 200 meters south of Chircal San Rafael. The San Rafael Formation crops out to the east of the Serrania de Arcabuco; it is also exposed along the axis of the Churuvita syncline. At its type locality, the formation may readily be divided into: (a) a lower unit of gray shales which weather to lighter tones with minor beds of thinly interbedded limestones; and (b) an upper unit consisting of thinly bedded, siliceous siltstones with several narrow bands of chert and toward the top, a single sha· le bed. The lower unit of the San Rafael is 60 meters (197 feet) thick at the type section, the upper unit is 14 meters (46 feet), giving a total fonnational thickness of 74 meters (243 feet). Whereas the lower unit is variable, the upper one is of remarkably uniform thickness. From the lower unit of the San Rafael Formation near the axis of the Churuvita syncline along the Sachica·Puen te·Samaca highway, several ce· phalopods have been collected; Paramammites colombianus n. sp., is described in the present report. CONEJO FORMATION (Upper Turonian ? -Lower Senonian pars) The Conejo Formation was first named by Renzoni (1967; published in Etayo Serna 1968a). Its type locality is the Alto del Conejo located on the Oicata.Chivata road, some 9 kilometers (5.6 miles) due northeast of Tunja. In the study area, the Conejo Formation crops out on the folds forming the margins of the Sa· maca-Sora Valley. The Formation is comprised of three units: (a) an unnamed lower part con· sisting predominantly of black shales with occa· sional thin interbeds of fine·grained sandstones or siltstones; (b) the middle, Cucaita Member which is exposed in the core of the Cucaita an· ticline. Its lower part is a series of calcareous shales alternating with several sandy limestones beds, the shales containing abundant calcareous concretions. The member as a whole takes on a whitish-yellow color due to the claystones toward the upper part which become progressively more arenaceous upward; and (c) an upper in· t.;rval, also unnamed, composed of yellow·white, quartzose sandstones intercalated with dark· gray, usually sandy shales. Near the top of the interval are found highly fossiliferous lenses of limestone. The total thickness of the Conejo Formation is 370 meters (1214 feet), divided as follows: lower interval, 80 meters (262 feet); Cucaita Member, 170 meters (558 feet); upper interval, about 120 meters (394 feet). In the area of this study, the contact with both the si· liccous siltstones of the San Rafael Formation and the overlying Plaeners Formation are con· fom1able. The middle, or Cucaita Member, has yielded the following assemblage described in the systematic part of this report. Nice{oroceras boyacaense n. sp. Peroniceras robertogarciae n. sp. Peroniceras diabloi n. sp. Peroniceras guerrai n. sp. Prionocycloceras (?) cucaitaense n. sp. Gloriaceras correai n. sp. 7
8 Gloriaceras paulinae n. sp. Zumpangoceras ospinai n. sp. Zumpangoceras (?) sorae n. sp. Buenoceras loboi n. sp. Protexanites cucaitaense n. sp. The uppermost part of the upper interval contains fossils of early Santonian age, including Lenticeras baltai Lisson. PLAENERS FORMATION (Santonian pars) According to Julivert (1968), the Plaeners Formation was frrst differentiated by Hubach (1931). The type section is located on the Sabana de Bogota, at "Boqueron de Tabio". The Plaeners can be traced from its type locality in· to the study area. It forms the prominent spur observed to the east of the Samaca-Sora Valley. The unit consists of a series of gray, siliceous siltstones in beds of 5-20 centimeters (2-8 inches) exhibiting rhomboidal fracture and rich in foramlnefera. The siltstones are frequently intercalated with beds and lenses of dark-gray chert and occasional layers of phosphatic sandstone. In the Quebrada San Joaquin, 50 meters {164 feet) are measured. The contact with the underlying Conejo Formation is conformable and with the overlying unit, gradational. GUADALUPE FORMATION Julivert (1968) states that Hubach in 1931 named {or perhaps more accurately, redefined) this unit from exposures in Cerros Guadalupe and Monserrate,immediately east of Bogota. The sequence forms the uppermost ·p.rominent cliffs to the east of the Samaca-Sora valley and represents the northern continuation of the sandstone of the same name which is exposed on the mountains surrounding the Saba· na de Bogota. The lower part consists of beds of siliceous argillites or siltstones, some of which tend to fracture rhomboidally. The overlyingTierna Sandstone is a white, yellow-weathering, coarse grained arenite which exhibits pro· mlnent cross-bedding toward its base. In the studied area the argillites reach a thickness of 50 meters (164 feet) and the overlying sands· tone 9 meters (30 feet). Contact of the lower part with the Plaeners is gradational, and contact of the Tierna Sandstone with the Guaduas Formation is conformable. WHE CRETACEOUS SECTION IN THE APULQ, - VlOTA, LAS MESITAS REGION, SEE TEXT·FJG. 2B. · L A NAVETA FORMATION ·-?:·.-. . '""- ·r· ., ;. . . • - . . The' name was originally introduced by Hubach (1931, p.44) to describe a sandstone horizon; it has been granted formational ranking by Caceres and Etayo-Sema (1965, p.5). Its name comes from the cement factory of that F. ETA YO· SERNA name. The unit crops out as the core of the Diamante anticline [Cerros del Diarnante to the north, and Cerro del Trueno to the south 1. The unit is well exposed on the road from La "Naveta Cement factory to Ingenio Central San Anto· nio (now Escuela Vocacional), just beyond the bridge over the Bogota River, or on the west limb of the El Diamante anticline where the type section was measured. The La Naveta Formation consists of a sequence of white to yellowish quartzitic sandstones, medium to coarse grained with frequent grains of chert; not very compact, with interbeds of shale rich in plant remains. The La Naveta Formation includes three units of member rank.(!) pi_-m.; ... ber; its name comes from the Ctirros D1amante; it consists of coralline limestones interbedded with shales and sandstones, the upper beds are 19 meters (63 feet) thick; it has been mined for use in cement. A specimen of Thurmanniceras sp. was found loose near the outcrop of the unit on the east flank of the El Diamante Anticline, north bank of Rio Bogota. (2) 'Th . J?.j; cal member; its name comes from Cerro de Bejiicanvnere it has been mined.lt is a biostrome of bivalves, worm tubes and a few corals. It yielded in situ: Heinzia (Carstenia) sp. The total thickness measured without having reached the base of the La Naveta Formation is 243 meters (801 feet). VILLETA GROUP This unit was established by Hettner {1892), it has been thoroughly reviewed by Julivert (1968); no type locality has yet been formally proposed. The name was introduced in this region by Hubach (1931, plate 1). Several units with formational rank have been proposed within the group; {1) the basal unit or Trincheras Formation named" after its type locaiitfat Quebrada Trlncheras. It consists of an alternation of limestone beds very rich in bivalves; its age is believed to be partly Barremian to Lower Ap· J!:!l. The lower and upper contacts are confor· mabie at the type locality. The formation crops out forming a band around the core of the El Diamante anticline; towards the northeast the formation changes into shales. The thickness measured at the type locality is 180 meters (594 feet). (2) The. Sos2!Lfl1Tlatiqn. The· .name was first used by Caceres and"Etayo-Sema (1969, p.5); it is derived from Quebrada Socota. This unit is intended to embrace the litho· logic sequence from the frrst graded quartzitic and calcareous sandstone at the base of the Socota Member (to be described next) which is -here taken as the basal member, and extending up to the first occurrence of porcellanite beds here considered the basal element of the overlying unit,_jhe_lliliL.Eormation. The type locality of the So"CcifaF"OrfiiatiO'if'tinilong the new road from Anapoima to Apulo, beginning at km 3 + 320. Except for its basal member the :socota Formation consists of a succession Of shales, they are superficially variegated but dark gray at depth; there are frequent calcareous concretions and · ·:gypsum veinlets usually crossing the bedding of the shales. The maximum thickness of the unit is estimated as 150 meters
Page 1 and 2: Publicaciones Geolo_gicas Especiale
Page 3 and 4: PUBLICACIONES GEOLOGICAS ESPECIALES
Page 5 and 6: CONTENTS ABSTRACT . . . . .. . . .
Page 7 and 8: Pl ate 4. Plate 6. Plate 6. Plate 7
Page 9 and 10: 2 F. ETA YO· SERNA The materials t
Page 11 and 12: 4 F. ETA YO· SERNA PHYSICAL STRATI
Page 13: FIGLH 1\ 2 2AJ Vl:LLA DE LEIVA CD -
Page 17 and 18: 10 F. ETA YO -SERNA coarse grained
Page 19 and 20: 12 F. ETA YO · SERNA trated in sev
Page 21 and 22: 14 F. ETA YO · SERNA ated. In the
Page 23 and 24: 16 F. ETA YO · SERNA TABLE I ASSEM
Page 25 and 26: 18 F. ETA YO ·SERNA tion consisfli
Page 27 and 28: 20 F. ETA YO ·SERNA increasing ove
Page 29 and 30: 22 has a subelliptical to subcircul
Page 31 and 32: 24 F. ETAYO ·SERNA rounds abruptly
Page 33 and 34: 26 F. ETAYO · SERNA ffer, 1963, p.
Page 35 and 36: 28 F. ETA YO - SERNA this is partic
Page 37 and 38: 30 F. ETAYO ·SERNA and bifurcate;
Page 39 and 40: 32 F. ETA YO · SERNA thirds of the
Page 41 and 42: 34 F. ETA YO · SERNA Hypotype. (U.
Page 43 and 44: 36 F. ETA YO - SERN A tuberculation
Page 45 and 46: 38 F. ETAYO - SERNA they project sl
Page 47 and 48: 40 last whorl the ribs are inconspi
Page 49 and 50: 42 Hypacanthoplites dognaliciae n.
Page 51 and 52: 44 F. ETA YO · SERNA One large spe
Page 53 and 54: 46 F. ETAYO - SERNA "Acanthoplites
Page 55 and 56: 48 F. ETA YO · ERNA These tubercle
Page 57 and 58: 50 .,CQ.IQmQ.ik.er::fJ§. W forg.ro
Page 59 and 60: 52 Among the subsequent flared ribs
Page 61 and 62: ZONATION OF THE CRETACEOUS OF CENTR
Page 63 and 64: ZONATION OF THE CRETACEOUS OF CENTR
Page 65 and 66:
zoNATION OF THE CRETACEOUS OF CENTR
Page 67 and 68:
Page 69 and 70:
ZONATION OF THE CRETACEOUS OF CENTR
Page 71 and 72:
? ? ZONATION OF THE CRETACEOUS OF C
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
86 F. ETA YO - SERNA rent localitie
Page 93 and 94:
88 The adapical end of this conch h
Page 95 and 96:
90 F. ETAYO · SERNA dies out near
Page 97 and 98:
92 OCCURRENCE. La Frontera Fonnatio
Page 99 and 100:
94 re is an asymmetrical sulcus bor
Page 101 and 102:
96 (1898, p. 198, figs. 23a,b,c), w
Page 103 and 104:
98 the flank and have a periventral
Page 105 and 106:
100 F. ETA YO - SERNA On the adapic
Page 107 and 108:
102 ventral third of the whorl side
Page 109 and 110:
104 but "Fundort: Von Stiibel im Be
Page 111 and 112:
106 F. ETA YO · SERNA En dos regio
Page 113 and 114:
108 In due regioni della Cordiglier
Page 115 and 116:
110 REFERENCES ANDERSON, F. M. 1938
Page 117 and 118:
112 -- 1963.- Atlas des fossiles ca
Page 119 and 120:
114 KARSTEN, H. 1858.- Vber die geo
Page 121 and 122:
116 Colon. Geol. min. Resourc., uol
Page 123 and 124:
118 F. ETA YO • SERNA WIEDMANN, J
Page 125:
120 A) B) C) D) E) F) G) H) I) L) M
Page 129:
124 F. ETA YO • SERNA A) B) C) D)
Page 133 and 134:
FIGURA 7 A Q 8 ) / ! E I c K FIGUR
Page 136 and 137:
132. A) B) C) D) E) F) G) H) I) J)
Page 138 and 139:
134 Scatter diagram of the distribu
Page 140 and 141:
136 Scatter diagram of the relation
Page 142 and 143:
Page 144 and 145:
140 F. ETA YO · SERNA Scatter diag
Page 146 and 147:
Page 148 and 149:
144 F, ETAYO ·SERNA Scatter diagra
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146 F. ETA YO · SERNA FIGURE 16 Sc
Page 152 and 153:
148 F. ETA YO · SERNA Scatter diag
Page 154 and 155:
PLATES 1-15
Page 157:
154 F. ETA YO · SERNA Fig. 1) Chel
Page 161:
158 F. ETA YO · SERN A PLATE 4 Fig
Page 165:
162 Fig. 1) Vectisites (Zambranoite
Page 169:
166 F. ETA YO · SERNA Fig. 1) Eodo
Page 173:
170 Fig. 1) Carloscaceresiceras cac
Page 179:
176 Fig. 1) Fig. 2) Fig. 3) Fig. 4)
Page 183:
180 Fig.1) Codaziceras scheibei (Ri
Page 186 and 187:
184 Engonoceras, 74. duartci, n. sp
Page 188:
186 Tegoceras, 82. benavidescaceres
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