Upper Magdalena Valley, Colombia

N. Jb. Geol. Paläont. Abh.

188

2

213-240

Stuttgart, Juni 1993

The Yavi Formation (Lower Cretaceous), Upper Magdalena Valley, Colombia: an integrated sedimentological and palynological study

Klaus F. Prössl and Luis Vergara Streinesberger, Gießen With 9 figures in the text PRÖSSL,K. F. & VERGARA STREINESBERGER, L. (1993): The Yavi Formation (Lower Cretaceous), Upper Magdalena Valley. Columbia: an integrated sedimentological and palynological study. - N. Jb. Geol. Paläont. Abh., 188: 213-240; Stuttgart. Abstract: Field work aiming an integrated sedimentological and palynological study of the Lower Cretaceous Yavi Formation, was carried out in the Upper Magdalena Valley. The Spores and pollen found in two of the samples allowed the dating of this unit as Early to Late Aptian. Some marine palynomorphs were found in the younger sample, within tide influenced fluviatile sequences. This indicates that the marine transgression was already present in the younger Early Aptian in the southern Upper Magdalena Valley. Zusammenfassung: Geländearbeiten im Oberen Magdalenatal in Kolumbien ermöglichten sedimentologische und palynologische Untersuchungen der unterkretazischen Yavi Formation. Die Sporen und Pollen, die in zwei Proben gefunden wurden, erlauben eine Einstufung" des bisher unbekannten Alter dieser Formation als Unter- bis OberAptium. Einige marine Palynomorphen wurden in der jüngeren Probe innerhalb einer tidal beeinflußten Abfolge gefunden. Sie belegen die marine Transgression ab dem späten Unter-Aptium im südlichen Oberen Magdalenatal. 15

N. Jb. Geol. Paläont. Abh. Bd. 188

0077-774919310188-0213 $7.00 O 1993 E. Schweizerbart'sche Verlagsbuchhandlung. D-7000 Smttgart 1

214

K. F. Prössl and L. Vergara Streinesberger

Resumen: A partir de trabajos de campo adelantados en el Valle Superior del Magdalena se presenta un estudio integrado sedimentologico y palinol6gico de la Formation Yavi. DOSde las rnuestras analizadas presentan polen y esporas que permiten la datacion de esta unidad en el Aptiano temprano a tardio. Hallazgos de palinomorfos marinos dentro de secuencias fluviales se interpretan como de origen mareal. De esta forma se evidencia la transgresion marina durante el Aptiano temprano superior en la parte sur de la cuenca del Alto Magdalena.

Introduction The Upper Magdalena Valley is an intramontane basin between the Central and Eastern Cordilleras of Colombia. Here, some 50000 bqd of oil are produced at present. It is considered to be a Cretaceous basin because of the petroleum generation during this period. The Yavi Formation is an Early Cretaceous lithostratigraphic unit lying between the Jurassic Saldaiia Formation and the transgressive Caballos Formation (Aptian-Albian), within the Upper Magdalena Valley. Its conglomeratic facies are thought to be of continental origin, although evidence for a marine environment had been found. These clastic series represent sediments derived from previously uplifted tectonic blocks of the Jurassic and from the adjacent A Where present, the Yavi Formation Central Cordillera (MOJICA& M A C ~1981). is the base of the Cretaceous in the Upper Magdalena Valley (MAciA et al. 1985: 62). Its deposition was followed by shallow marine sediments, produced by the great Cretaceous transgression reaching the Upper Magdalena Valley during Aptian times (ETAYOet al. 1969). A precise dating of the Yavi Formation was not possible until now because of the lack of fossils. Nevertheless, various suggestions have been proposed, as will be discussed later. The aim of this paper is to present preliminary palynological data in association with a sedimentological analysis of the Yavi Formation. By means of the former we tackle the question of its age and we discuss aspects of its facies based on sedimentological relationships and on the paleontological findings. These data considerations of the Upper Magdalena Valley. allow pale~geogra~hic At first a detailed stratigraphic section in the Quebrada Palmorosa was drawn (scale 1 :50) during field activities in 1990. Ten samples for palynological study from the Yavi and Caballos formations were selected.

Previous work In spite of previous work concerning the Yavi Formation, the first to (1981). Their introduce the name in a publication were MOJICA& M A C ~ A work is therefore currently accepted as the reference definition.

The Yavi Formation, Upper Magdalena Valley

215

The formation was first described at the type locality of the Rio Yavi, 12.5 km south of Prado (Tolima). MAC~A et al. (1985) present a map of outcrops for the Yavi Formation that reveals two major accumulation areas: a northern basin, located mostly in the province of Tolima, and a southern basin, south of

Fig. 1. a) Geographical location and access to the Quebrada Palmorosa Section; b) Geological situation of the Yavi Formation (dotted) in the study area (after FUQUENet al. 1989). Jin = Los Naranjos Stock; JRs = Saldafia Formation; Ky = Yavi Formation; Kv = Villeta Formation; Kc = Caballos Formation; Kg = Guadalupe Formation; TKg = Guaduas Formation.

216


the rise of Yaguari-Teruel. The thickness of the formation varies from Zero (e. g. Payandi) up to 653 m in the Coyaima-Ataco area; this is interpreted as tectonic controlled sedimentation (MOJICA& MAciA 1981). The age of the Yavi Formation has been presumed to be Jurassic to Lower Cretaceous by MOJICA& M A C ~ (1981), A based on its stratigraphic position between the Saldaiia and Caballos formations. The latter age is accepted because of the continuity between the sediments of the Yavi and the Aptian-Albian Caballos Formation. GUILLANDE (1988) documents a silicified tree log from the Yavi Formation, identified as Metapodocarpoxylon libanoticum (EDWARDS), but its known stratigraphic range is Middle Jurassic to Middle Cretaceous. fig. 15 (1988) shows the Yavi Formation O n the other hand, MACERALLI'S with a Barremian-Lower Aptian age.

Study Area The studied area is located near the village of Aipe, Departamento del Huila, Colombia. For accessibility of the section of the Quebrada Palmorosa see Fig. la. The geological setting of the Yavi Formation in the study area is related to the Media Luna Syncline (see Fig. Ib), which lies on the above mentioned northern depositional basin of M A C ~etA al. (1985). This area belongs to the so called Neiva Sub-basin of the Upper Magdalena Valley (BELTRAN& GALLO 1968).

Sedimentology The Rio Yavi (Prado-Dolores) Type Section According to MOJICA& M A C ~(198l), A the unit at the type section of the Rio Yavi consists of 35 m conglomerates of volcanic, pyroclastic sandstone and siltstone pebbles deposited above the eroded volcanic series of the Saldaiia Formation. These basal strata are overlain by a thick series of red feldspatic sandstones alternating with varicolored claystones that grade into the sandstones of the Caballos Formation. The total thickness of the Yavi Formation at its type locality reaches about 320 m. The Quebrada Palmorosa Section The following lithological succession of the Yavi Formation is shown in Fig. 2. For sedimentological purposes it has been attempted to reproduce as much of the predominant layer geometry and internal stratification structures as possible. Selected intervals where the samples yielded palynomorphs are displayed in enlarged sections (Fig. 3).


217

LV-01

0 "

"

-

? O "

0 "

-

"

0

"

0 . 1 -

V

Fig. 2. Stratigraphic column of the Yavi and lowermost Caballos Formation showing the most predominant internal structures. For enlarged sections and explanation of sedimentary structures see Fig. 3. F o r a key to the lithology see lower scale.

According to the prevalent lithology the unit was divided into the following two Segments: Segment I This 88 m thick section is the lowest, conglomeratic segment of the Yavi Formation. Its base outcrops at the road to the Vereda Chilirco adjacent to the Quebrada Palmorosa. The contact between porphyritic rocks of the Saldaiia Formation and the lower conglomerates of the segment is discordant. At Quebrada Palmorosa, these conglomerates contain chert, volcanic and metamorphic pebbles floating in a lithic-feldspatic, medium to coarse sand-

218


SEDIMENTARY STRUCTURES

-

Interna1 Lanination:

e

Z &V

*

P a

B

even, p a r a l l e l even, n o n p a r a l l e l uavg. n o n p a r a l l e l inclined Cross bedding erosive surface palynonorphs lebensspuren Foraninifera Bivalves intraclasts

m

t r e e logs

LV- 14

*

H-3

&! -

-

8 LV-15

1 -

n 1

0

--

1

-

2

H-7

H-3

6

LU-15-0 H-7

concretions

@

fish scales

B

Aptgchi

-I

bio

-I

I . . . .

Fig. 3. Enlarged sections selected in Fig. 2. See lower scale for a key to the lithology.

stone matrix and are commonly intercalated with fine sandstone banks. The sandstones were classified in this section as feldspatic lithoarenites (FOLK 1968 ex SCHOLLE1981). Most of them typically contain a sericitic matrix and diagenetic calcitic cement. Its textural characteristics show slight reworking. In Segment I, the ocurrence of erosive surfaces is common. Normally they are overlain by conglomerates or sandstones with intercalated thin sheets of conglomeratic layers and carbonized tree stumps. They grade upward into finer material and sometimes even fine layers of mud and muddy sandstone appear at the top of the'sequences. This case is illustrated in the enlarged section A of Fig. 3. These fining-upward sequences bounded by erosion surfaces are interpreted as channel lags (COLLINSON 1989: 52; ALLEN1970; REINECK & SINGH1973:


219

231). Its subsequent repetition suggests cycles (cf. "small-scale cyclic sequences") of channel Systems (MIALL1978: 600, fig. 1; RUST1981: 19). The facies of the Segments resemble that of a braided stream. This is based on the lack of mud intraclasts or light-coloured flood plain deposits (EYON& WALKER1974: 44; WALKER& CANT1981: 27), as well as the predominance of planar gravel sheets over the cross-bedding (SMITH1970: 3004). Besides this, little evolution is revealed by the textural features. However, the conglomerates seldom appear clast-supported, as in typical braided stream deposits (e. g. WILLIAMS& RUST 1969; RUST 1981: 16), questioning the existence of an exclusive braided hydrodynamic regime. The similarity between ancient braided and meandering stream deposits has been demonstrated. WALKER& CANT (1981 : 27), for instance, remarks that the fundamental processes controlling braided and meanderinsg Patterns are not fully understood. The existence of marine palynomorphs in sample LV-05 is attributed to marine processes that will be discussed later (see Discussion).

Segment I1 Of its 40 m of assumed thickness, 29 m crop out at the section. It is characterized by alternating sandstones and mudstones where coarse grained sediments are absent. Fine sandstones appear intercalated with white mudstones having varicoloured specks and lenticular, very fine sand bodies in it. N o internal structures, such as lamination, are evident in these mudstones. Petrographically, the sandstones are classified as lithic arcoses (FOLK1969 ex SCHOLLE1981), with a chloritic and ferruginous cement. The first occurrence of mud intraclasts and "lebensspuren" (Skolithos ?) in the formation is of particular importance in this segment (see Fig. 3 B for details). An increase in fine sediments, interpreted as vertical accretion deposits, Supports the hypothesis of a sinuous river (HARMSet al. 1982: 5-5). The occurrence of "sand lenticules interbedded with shales" is similar to that from the high & CANT(1981: 26). The white colour sinuosity meandering model of WALKER (N9) of the mudstones suggests a large content of kaolinite. This feature is associated with a vegetated flood plain (e. g. in the Nubia Strata of southern et al. 1982: 5-19). Egypt; HARMS Segment I1 as well as the lower sandy segment of the overlying Caballos Formation represents the transition to the full marine environment of the latter unit. The presence of the mentioned ichnofossils indicate once again a marine connection.

Upper Boundary In previous works this limit has been carelessly placed within undifferentiated sandstones of the (?)Yavi or Caballos Formation (see MOJICA& MAciA 1981, 1988; MILEY1945), leading to confusion. fig. 9; GUILLANDE

220


In this paper the top of the highest traceable mudstone bed of segment I1 (as Seen in Fig. 2) is picked as the contact between the Yavi and the Caballos A Formation, as in the type section of Prado-Dolores (MOJICA& M A C ~ 1981 fig. 9). It is a practical limit within a gradational series, as contemplated by the North American Stratigraphic Commission on Stratigraphic Nomenclature (1983: 856). The next younger mudstone layers that outcrop in the column are laminated, black to gray shales, intercalated with carbonate rocks of the Caballos Formation (see Fig. 2). This allows no confusion with those of the Yavi Formation.

Lower Caballos Formation This unit is shortly dealt with in this paper because sample LV-14 (see Fig. 3), from its lowest part, yielded palynomorphs that Support the results from the Yavi Formation. It is mainly a sandstone unit, deposited transgressively in most of the Upper Magdalena Valley. The age is assumed to be early Aptian to Albian (CORRIGAN 1967: 231) based on biostratigraphy presented by BÜRGL(1961). This author, however, points out that no pre-Albian fossils were found in the studied area near Ortega (BÜRGL1961: 25). BELTRAN& GALLO(1968: 256) consider the unit to be Lower Aptian to Middle Albian. However, these assumptions are not supported paleontologically. Since there are no biostratigraphical data published, the palynomorphs reported here permit to date more reliably the lower Part of the Caballos Formation (see Discussion). The lowermost beds are medium-grained sandstones with noticeably inclined laminae. Some thin sideritic lenses are present. Overlying this sandy section the lower shale-carbonatic segment of the Caballos Formation is deposited. It consists of beds of biomicrites, intercalated with black laminated shales. These carbonates are commonly rich in macrofossils such as lamellibranchs, aptychi and fish remains. Abundant fish scales are found in the intercalated shales. Biomicrites grade to biosparites and even to a biosparudite containing shells of gravel size, deposited randomly with respect to the bedding surface (see enlarged section C, Fig. 3). A detailed analysis of the lower Caballos Formation is not intended in this study. Nevertheless it is important to point out that it looks very much like the segment I1 of the Yavi Formation (i. e. transitional facies), but clearly becoming marine upwards in the rock record.

Palynology Three samples of the lowermost 200 m of the studied succession yielded palynomorphs. All of the samples were dark grey to very dark grey silty sandstones with no lime content. They were treated with acid (HCl, HF) and sieved, without any kind of oxidation. Ten slides of each sample were prepared for analyses.


22 1

O n e sample (LV-14) belongs t o the Caballos Formation, the other ones (LV-4 a n d LV-5) t o t h e Yavi Formation. T h e p a l y n o m o r p h s of t h e latter are reported here. A l t h o u g h nearly all t h e organic contents a r e represented by o p a q u e a n d m o r e o r less degraded land plant debris, t h e following well preserved palyn o m o r p h s w e r e identified. T h e r e p o r t e d stratigraphic distribution w a s compiled by RAVN (1990) a n d is completed by o w n unpublished data. I n sample LV-4:

Callialasporites trilobatus (BALME1957) DEV1961 (Rhaetian-Late Albian), Fig. 5.15. Cicatricosisporites sp. cf. C. imbricatus (MARKOVA 1961) SINGH1971 (Berriasian-Cenomanian), Figs. 6.1,6.4. Cicatricosisporitesimplexus Yu in MIAOet al. 1984 (Portlandian-Berriasian), Figs. 5.12-13. Contignisporites cooksoniae (BALME1957) DETTMAN1963 (Hettangian-Early Albian), Fig. 5.11. Crybelosporites sp. A, Fig. 5.14. Cvybelosporites sp. B. Echinatisporis varispinosus ( P o c o c ~1962) SRIVASTAVA 1977 (Carixian-Maastrichtian). Echinatisporis cf. varispinosus, Figs. 5.3,5.6,5.10. Is~h~osporites variegatus (COUPER1958) SCHULZ1967 (Rhaetian-Albian). Leptolepidites iwegularis (BRENNER1963) WINGATE1980 (Early Aptian-Late Cenomanian), Figs. 6.6-7. Lycopodiumsporites solidus BURGER1980 (Late Jurassic-?Albian), Figs. 5.1,5.4. Monosulcites spinosus BRENNER 1963 (Aptian-Albian), Figs. 5.2,5.5. Neoraistrickia truncata (COOKSON 1953) POTONIE1956 (Late Trassic-Late Albian). Retimonocolpites sp. cf. R. reticulatus (BRENNER1963) DOYLEin DOYLEet a1.1975 (Barremian-Cenomanian), Figs. 6.2-3,6.5. Smooth trilete spores g. et sp. indet. Bisaccate pollen g. et sp. indet. In sample LV-5: Afropollis Sp. A DOYLEet al. 1982 (younger Early Aptian; C V11 C), Figs. 8.2, 8.5. Araucariacites sp. Baculatisporites sp. cf. B. comaumensis (COOKSON1953) POTONIE 1956 (RhaetianMiocene). Callialasporites minus (TRALAU1968) GUY1971 (Bajocian-Late Kimmeridgian), Fig. 8.9. Callialasporites trilobatus (BALME1957) DEV1961 (Rhaetian-Late Albian). Callialasporites turbattts (BALME1957) SCHULZ1967 (Sinemurian-Aptian), Fig. 7.6. Cicatricosisporites l u d b r 0 o k i a e . D ~1963 ~ ~(Valanginian-Late ~~~~ Albian), Figs. 9.6-7. Cicatricosisporitespurbeckensis NORRIS1969 (Valanginian-Early Aptian?). Cicatricosisporites sp. cf. C. purbeckensis, Figs. 7.2, 7.4. Cicatricosisporites implexus Yu in MIAOet al. 1984-(Portlandian-Berriasian). Cicatricosisporites potomacensis BRENNER1963 (Valanginian-Cenomanian), Figs. 7.1, 7.3,9.16. Concavissimisporites variverrucatus (COUPER1958) BRENNER1963 (Callovian-Late Albian), Fig. 8.12. Echinatisporis varispinosus ( P o c o c ~1962) SRIVASTAVA 1977 (Carixian-Maastrichtian), Figs. 9.11-12. Ischyosporites areolatus (SINGH1971) FENSOME1987 (Late Barremian-Middle Albian), Figs. 9.3-4.

222


Ischyosporites foveolatus ( P o c o c ~1964) FENSOME 1987 (Late Jurassic-Campanian), Figs. 8.8, 8.11. Ischyosporites cf. foveolatus. 1958) DÖRING1965 (Oxfordian-Turonian), Ischyosporites pseudoreticulatus (COUPER Figs. 8.1, 8.4. Ischyosporites variegatus (COUPER 1958) SCHULZ 1967 (Rhaetian-Albian), Figs. 9.10,9.14. Ischyosporites cf. variegatus, Figs. 9.13,9.15. Leptolepidites irregularis (BRENNER 1963)WINGATE 1980 (Early Aptian-Late Cenomanian). Lycopodiumsporites dentimuratus BRENNER 1963 (Barremian-Early Cenomanian), Figs. 9.5,9.8-9. Nodosisporites sp. cf. N . Aentimarginatus (BRENNER 1963) DAVIES 1985 (Berriasian-Cenomanian), Figs. 8.3,8.6. Smooth trilete spores g. et sp. indet. Zonasulculate pollen g. et sp. indet., Fig. 8.13. Bisaccate pollen g. et sp. indet. g. et sp. indet., Figs. 8.7,8.10. Tricolporate Acanthomorph acritarch g. et sp. indet., Figs. 9.1-2. Dinocyst g. et sp. indet. Uniserial foraminiferal inner lining g. et sp. indet., Fig. 7.5.

The palynological content of samples LV-4 and LV-5 is very different. Only some species occur in both samples. Sample LV-4 is dominated by the presence of Leptolepidites irregularis with minor quantities of Cicatricosisporites spp., whereas in sample LV-5 the dominance of Ischyosporites variegatus is .. accompanied with Cicatricosisporites spp. and Lycopodiumsporites dentimuratus. Remarkable for a location in the pre-Albian floral province of northern Gondwana, is the absence of Ephedripites, Stellatopollis and attendant spores and pollen. Such an association was-reported by -DOYLE et al. (1982) for a comparable sample from the Restrepo Formation near Villavicencio, Colombia. The Yavi association is also less similar to a sample which was supposed to be late Aptian by PONS (1982). Furthermore bisaccate pollen, Classopollis and related species are rare or absent. Only Araucariacites sp. is present in minor quantities. The dominance of cyatheacean and schizaeacean plants suggests a warm, humid, subtropical or tropical climate during that time. - -

Spore and pollen species

Callialaporites trilobatus Isc/iyosporitesvariegatus Callialasporites turbatus Concavissimirporitesvarivemcatus Contignisporitescookroniae Lycopodiumsporites solidus Cicatricosisporitesimplexus Cicatricosisporitespotomacensis Cicatricosisporitesludbrookiae Cicatricosisporitespurbeckensis Lycopodiumsporites dentimuratus Ischyosporites areolatus Leptolepidites irregularir Monosulcites spinosus Afropollis sp.A

Tr

---m --

---Ju

LCr

Barremian

Aptian

i

m -

--B

i

?

B I

I

I

UCr

i I

I I I I I I I I

----

Albian

--

?

I I

Fig. 4. Stratigraphie distribution of some selected spores and ollen present in LV-4 and LV-5, compiled after RAVN(1990) and own unpublished data. Tr = Triassic, Jr = Jurassic, LCr = Lower Cretaceous, UCr = Upper Cretaceous.

The Yavi Formation, Upper Magdalwa Valley

223

Systematic description The provisional assignment of the following spores and pollen to the botanical System depends on the suggested affinity of the species to some plant families by several authors (BRENNER 1963, COUPER1958, DETTMAN1963, GUY1971 etc.). All slides are stored under the referred number in the collection of the Institut für Angewandte Geowissenschaften, Diezstraße 15, D-6300 Gießen. Pteridophyta Lycopsida Lycopodiales Lycopodiaceae

Genus Lycopodiumsporites THIERGART 1938 Lycopodiumsporites dentimuratus BRENNER 1963 Figs. 9.5,9.8-9 H o l o t y p e : BRENNER 1963, p. 44; pl. 5, fig. 4. Stratigraphic d i s t r i b u t i o n : Barremian-Early Cenomanian, LV-5. Remarks : The specimens with a maximum diameter of 32 p m fit into the range

reported by BRENNER. Also the overall shape and the Ornament of the spore resemble the holotype in detail.

Lycopodiumsporites solidus BURGER 1980 Figs. 5.1,5.4 H o l o t y p e : B U R G E R1980, P. 53; pl. 8, fig. 7. Stratigraphie d i s t r i b u t i o n : Late Jurassic-?Albian, LV-4.

Remarks: Although BURGERSholotype is damaged, the spore found in the Yavi Formation is very similar to it. Especially the ornamentation and the trilete laesurae, which seems to be mainly present in the innermost layer, are similar. The Colombian specimen is at 45 p m somewhat smaller than those of BURGER.

Genus Echinatisporis KRUTSCH 1959

Echinatisporis varispinosus (POCOCK1962) SRIVASTAVA 1977 Figs. 9.11-12 Holotype: P o c o c ~ 1962, p. 36; pl. 1, figs. 18-19. Stratigraphie d i s t r i b u t i o n : Carixian-Maastrichtian, LV-4, LV-5.

R e m a r k s : With a diameter of 23-28 p m the specimens fit into the range given . the arrangement and development of the spines is similar, by P o c o c ~ Also but no bifurcation at the tips was observed. POCOCK(1962) pointed out that their a affinity to selaginellous spores.

224


Echinatisporis cf. varispinosus Figs. 5.3,5.6,5.10 Stratigraphic d i s t r i b u t i o n : probable younger Early Aptian, LV-4. R e m a r k s : The most significant difference to the Spores described by P o c o c ~

(1962) are the very short and broad spines. Frequently two slender ones arise from one base. The diameter of the spore is about 28 pm, the spines are 3pm in maximum length and up to 3 p m in breadth.

Genus Neoraistrickia POTONIE1956 Neoraistrickia truncata (COOKSON 1953) POTONIE1956 Figs. 5.7-9 1953, p. 471; pl. 2, fig. 36. H o l o t y p e : COOKSON Stratigraphic d i s t r i b u t i o n : LateTriassic-Late Albian, LV-4.

R e m a r k s : Although the size of the spore is only about 2/3 of the minimum (1953) it shows all characterisitics of N . truncata. range given by COOKSON In addition the small diameter (20 pm), the specimen possesses the Same number of truncate processes.

Filices Leptosporangiatae Filicales Cyatheaceae

Genus ConcavissirnisporitesDELCOURT & SPRUMONT 1955, emend. DELCOURT, DETTMANN & HUGHES 1963 Concavissimisporites variverrucatus (COUPER 1958) BRENNER 1963 Fig. 8.12 H o l o t y p e : C o u p e r 1958, p. 142; p l . 22, fig. 4. Stratigraphic d i s t r i b u t i o n : Callovian-Late Albian, LV-4.

R e m a r k s : The figured specimen shows more affinity to those shown by COUPER(1953) on pl. 22, fig. 5 than to the holotype. However, with its diameter of about 53 p m and its verrucate surface, the spore is within the previous reported range.

Genus Leptolepidites COUPER1953, emend. NORRIS1968 Leptolepidites irregularis (BRENNER 1963) WINGATE 1980 Figs. 6.6-7 1963, P. 64; pl. 17, fig. 4. H o l o t y p e : BRENNER Stratigraphie d i s t r i b u t i o n : Early Aptian-Late Cenomanian, LV-4, LV-5.

R e m a r k s : The specimens from the Yavi Formation are typified by a very significant gemmate sculpture. The range is 33-47 p m in diameter. Previously the first occurrence of this species was reported in the Early Albian.

The Yavi Formation, Upper Magdalena Valley Polypodiaceae

Genus Crybelosporites DETTMANN 1963 Crybelosporites sp. A Fig. 5.14 Stratigraphic d i s t r i b u t i o n : probable younger Early Aptian, LV-4.

R e m a r k s : The specimen is about 47 p m in longitudinal axis and 45 p m in equatoral diameter. The outer and inner layer are compressed, except for the ~roximaland equatorial area. The specimen r e ~ o r t e das Cybelosporites sp. B is about 70 p m in longitudinal axis and shows no compresssion of the layers. 1947 ex COUPER1953 Genus Monosulcites COOKSON

Monosulcites spinosus BRENNER 1963 Figs. 5.2, 5.5 H o l o t y p e : BRENNER 1963, p. 96; pi. 42, fig. 2. S t r a t i g r a p h i c d i s t r i b u t i o n : Aptian-Albian, LV-4.

R e m a r k s : The body of the spore is smaller (22 pm) than the range given by BRENNER (1963), but the length of the spines and their arrangement is similar. In Fig. 5.5 the vertical developed sulcus is visible. Schizaeaceae

Genus Cicatricosisporites POTONIE& GELLETICH 1933

Cicatricosisporites ludbrookiae DETTMANN 1963 Figs. 9.6-7 H o l o t y p e : DETTMANN 1963, p. 54: 9, figs. 17-18. Stratigraphie d i s t r i b u t i o n : Valanginian-Late Albian, LV-5.

Remarks: Although the spores from the Yavi Formation show a diameter of only 47 pm, they possess all features of the holotype.

Cicatricosisporites sp. cf. C . purbeckensis NORRIS1969 Figs. 7.2,7.4 H o l o t y p e : NORRIS 1969, p. 588; pl. 104, fig. 6. Stratigraphie d i s t r i b u t i o n : probable younger Early Aptian, LV-5.

R e m a r k s : The distal ornamentation of the specimen is not developed strongly parallel to the equatorial sides. N o ornamentation on the proximal contact area is visible. It is smooth and bordered by a rim. The maximum diameter is about 50 Km.

Cicatricosisporites sp. cf. C. irnbricatus (MARKOVA 1961) sensu SINGH1971 Figs. 6.1,6.4 T y p e : SINGH1971, p. 74, pl. 9, fig. 6. S t r a t i g r a p h i c d i s t r i b u t i o n : younger Early Aptian-Middle Albian, LV-4.

R e m a r k s : The specimen resembles in all details to the description given by SINGH(1971).

226


Cicatricosisporitesimplexus Yu in MIAOet al. 1984 Figs. 5.12-13 H o l o t y p e : Yu in MIAOet al. 1984, p. 521; pl. 200, figs. 22-23. Stratigraphic d i s t r i b u t i o n : Portlandian-late Aptian, LV-4, LV-5.

R e m a r k s : The specimens from Colombia match perfectly the description given by HUNT(1985) for the synonym species C. sinuosus. Specimens of C. implexus were also found in Late Aptian marls of the Gargasian in South France near la Bidoule.

Cicatricosisporitespotomacensis BRENNER 1963 Figs. 7.1, 7.3,9.16 H o l o t y p e : BRENNER 1963, p. 50; pl. 9, fig. 4. S t r a t i g r a p h i c d i s t r i b u t i o n : Valanginian-Cenomanian, LV-5.

R e m a r k s : The maximum diameter of the specimens found in the Yavi Formation extends from 44 p m to 59 pm.

1963 Genus Contignisporites DETTMANN Contignisporites cooksoniae (BALME1957) DETTMANN 1963 Fig. 5.1 1 H o l o t y p e : BALME1957, p. 19;pl. 1, fig. 23. Stratigraphie d i s t r i b u t i o n : Hettangian-Early Albian, LV-4. R e m a r k s : The figured specimen has a maximum diameter of 28 p m and shows

a comparatively wide cingulum of about 5 pm. Therefore it might show some affinities with C. burgeri FILATOFF& PRICE1988, but it lacks the proximal ornamentation. Genus Ischyosporites BALME1957

Ischyosporites areolatus (SINGH1971) FENSOME 1987 Figs. 9.3-4 H o l o t y p e : SINGH1971, p. 94; pl. 13, figs. 4,5. Stratigraphic d i s t r i b u t i o n : Late Barremian-Middle Albian, LV-5. R e m a r k s : With a diameter of about 40 pm, the specimen is somewhat smaller

than the range given by SINGH(1971), but it shows the distinct angular luminae.

Ischyosporites foveolatus ( P o c o c ~1964) FENSOME 1987 Figs. 8.8, 8.11 Holotype: P o c o c ~ 1964, p. 194; pi. 7, figs. 5,6. Stratigraphic d i s t r i b u t i o n : Late Jurassic-Campanian, LV-5.

R e m a r k s : The ornamentation is more dense than those of the holotype and resembles the specimens figured by SINGH(1971).


Ischyosporitespseudoreticulatus (COUPER1958) DÖRING1965 Figs. 8.1, 8.4 H o l o t y p e : COUPER 1958, p. 138; pl. 19, figs. 8,9. Stratigraphic d i s t r i b u t i o n : Oxfordian-Turonian, LV-5.

R e m a r k s : The specimen is 40 p m in diameter and shows clearly the encroachment of the distal sculpture on to the proximal surface.

Ischyosporites variegatus (COUPER1958) SCHULZ1967 Figs. 9.10,9.14 H o l o t y p e : COUPER 1958, P. 137; pl. 19, fig. 7. S t r a t i g r a p h i c d i s t r i b u t i o n : Rhaetian-Albian, LV-4, LV-5. R e m a r k s : The size range of the specimens from the Yavi Formation is 36 p m

to 46 pm.

Is~h~osporites cf. variegatus Figs. 9.13,9.15

Stratigraphie d i s t r i b u t i o n : probable youngerEarly Aptian. R e m a r k s : The sculptural elements of the specimens belonging to this group are less well developed than those of I. variegatus. This may be is a question of the maturity of the Spores.

Genus Nodosisporites DEAK1964

Nodosisporites sp. cf. N . dentimarginatus (BRENNER 1963) DAVIES1985 Figs. 8.3,8.6 H o l o t y p e : BRENNER 1963, p. 45; pl. 6, figs. 2. Stratigraphie d i s t r i b u t i o n : Berriasian-Cenomanian, LV-5.

R e m a r k s : In contrast to N . dentimarginatus, the figured specimen shows also some spines on the proximal surface. Gymnosperm pollen

Genus Callialasporites DEV1961 Caliialasporites minus (TRALAU 1968) GUY1971 Fig. 8.9 H o l o t y p e : TRALAU 1968, P. 96; pl. 13, fig. 4. Stratigraphic d i s t r i b u t i o n : Bajocian-Late Kimmeridgian, LV-5.

R e m a r k s : The previously reported last occurrence of C. minus was Late Kimmeridgian. Reworking is doubtful because of the good preservation of the figured specimen. The diameter is 40 p m in equatorial view.

Callialasporites trilobatus (BALME1957) DEV1961 Fig. 5.15 H o l o t y p e : BALME1957, p. 33;pl. 8,figs. 91,92. Stratigraphic d i s t r i b u t i o n : Rhaetian-Late Albian, LV-4, LV-5. R e m a r k s : The figured specimen shows only less developed sacci.

228


Callialasporites turbatus (BALME 1957) SCHULZ1967 Fig. 7.6 H o l o t y p e : BALME1957,p. 31;pl. 7,figs. 85,86;pl. 8,fig. 87. S t r a t i g r a p h i c d i s t r i b u t i o n : Sinemurian-Aptian, LV-5.

R e m a r k s : The figured specimen shows some destruction, but also specimens in good conditions were found.

Genus Equisetosporites DAUGHERTY 1941, emend. SINGH1964

Equisetosporites ambiguus (HEDLUND 1966) SINGH1983 Fig. 9.17 1966, p. 27; pl. 8, figs. 3a, 3b. H o l o t y p e : HEDLUND S t r a t i g r a p h i c d i s t r i b u t i o n : Early Albian-LateTuronian, LV-14. R e m a r k s : The specimen found in sample LV-14 was accompanied by some

dinoflagellate cysts. Although the preservation is not very good, all significant features are visible. Incertae sedis

Zonasulculate pollen g. et sp. indet. Fig. 8.13

R e m a r k s : This zonosulculate pollen is partly destroyed and shows a slight ganular surface with a smooth sulcal area. It was found in sample LV-5. Angiosperm pollen

Genus Afropollis DOYLE et al. 1982

Afropollis sp. A DOYLE et al. 1982 Figs. 8.2, 8.5 T y p e : DOYLE et al. 1982, p. 50; pl. 12, figs. 1-4. Stratigraphic d i s t r i b u t i o n : upperearly Aptian (C V11 C),LV-5.

R e m a r k s : In the description given by DOYLE et al. no size range was given. Their figured specimen is about 33 p m in diameter. The specimen from the Yavi Formation is 27 p m in diameter and resembles in ornamentation and structure et al. 1982. the s~ecimenof DOYLE

Genus Retimonocolpites PIERCE 1961 Retimonocolpites sp. cf. R. reticulatus (BRENNER 1963) DOYLE in DOYLE et al. 1975 Figs. 6.2-3,6.5 H o l o t y p e : BRENNER 1963, p. 94; pl. 41, figs. 3,4. Stratigraphic d i s t r i b u t i o n : Barremian-Cenomanian, LV-4.

R e m a r k s : This pollen resembles in most features R. reticulatus, except the diameter and the shape of the central body. The central body is almost circular and is 25 p m in diameter. R. reticulatus has a slightly subcircular central body with a maximum diamter of 22 pm.


Incertae sedis Tricolporate pollen g. et sp. indet. Figs. 8.7,8.10

R e m a r k s : The sculptural elements consisting of very low verrucae and the overall habitus show some affinities to Nothofagus. The specimen was found in sample LV-5. Acritarcha Acanthomorphitae Acritarch g. et sp. indet. Figs. 9.1-2

R e m a r k s : In sample LV-5 a bad preserved acritarch or dinoflagellate cyst was found. The specimen shows a smooth to slightly granular central body of 20 p m in diamter. The processes are smooth and solid with acicular tips and have a length up to 25 pm. Foraminiferida Incertae sedis Uniserial foraminiferal inner lining g. et sp. indet. Fig. 7.5

R e m a r k s : The specimen may belong to the families Nodosariidae o r Pleurostomellidae. Its deformed chambers can be due to diagenesis. It is present in sample LV-5.

Discussion Concerning the depositional environment of the Yavi Formation, the finding of marine palynomorphs, such as acritarchs, dinoflagellate cysts (Figs. 9.1-2) and foraminifera (Fig. 7.5) in the lower Segment, represents an irrefutable argument proving at least a partial marine environment, interpreted previously A al. (1985: 62) also identified as continental (MOJICA& MAciA 1981). M A C ~et trace fossils in the Yavi Formation and associated them to marine ingressions. Other deposits formed by alluvial processes, with marine fossils in their fine grained intercalations are documented in RUST(1981: 19) and in a so called "alluvial-tidal complex" in DAILEY et al. (1981). The marine connection must have been sporadic as the marine palynomorphs are very rare, and the bed containing them is only a few centimeters thick. The deposition was controlled by marine floods penetrating landwards or by an alluvial system prograding into the sea with a stable sea level, but most likely by tidal action. Therefore, a siliciclastic shoreline (sensu ELLIOT1989), i. e. a depositional system involving tidal phenomena, is supported. A sequence stratigraphical interpretation in relation with sea-level oscillations was recently STREINESBERGER (1992). carried out in this section (Q. Palmorosa) by VERGARA 16

N. Jb. Geol. Palaont. Abh. Bd. 188

230


From Fig. 4 the suggested age of the samples is evident. The stratigraphic distribution of some selected Spores and pollen makes a late early Aptian age most probable. The age of the samples LV-4 and LV-5 is supported by the last occurrences of Callialasporites turbatus and Cicatricosisporites purbeckensis in the Aptian, together with the first occurrences of Monosulcites spinosus, Afropollis sp. A and Leptolepidites irregularis. Whereas the former are reported in the Early 1963),the first appearance Aptian by several authors (DOYLEet al. 1982, BRENNER of the latter was previously documented in the Early Albian (BRENNER 1963). Bearing in mind the first occurrences of the last mentioned palynomorphs and an interval of about 140 m in the section to a younger sample (LV-14), with an age not older than Early Albian, the occurrence of this Spore must be earlier. For dating sample LV-14, besides Equisetosporites ambiguus (Fig. 9.17) the dinoflagellate cysts Cribroperidinium intricatum and Pseudoceratium retusum are good evidence. The latter has its stratigraphic range from the Barremian to the middle Albian. Cribroperidinium intricatum occurs during the Albian to Cenomanian. So the oldest possible age for this association in sample LV-14 is Early Albian. Considering the above mentioned interval between this sample and the ones of the Yavi Formation, a young Early Aptian age for samples LV-4 and LV-5 is most probable. Therefore the Yavi Formation seems to be deposited during early to late Aptian times. A very late Aptian age for the lower Part of the Caballos Formation is still possible. After proving a marine connection and an early Aptian age for the Yavi Formation it is worthwhile to take a look at the transgressive contours of the paleogeographic map of ETAYOet al. (1969). According to figs. 2 and 13 of these authors, the sea advanced southwards from the area corresponding to the present Eastern Cordillera. During the Early Aptian it reached the Upper Magdalena Valley up to the northern Part of the corresponding "northern basin" (Payandk area) of the Yavi Formation. This is still some considerable distance from the Aipe region, far more than the range of a conventional tide, bearing in mind the steep paleotopography of pre-Cretaceous tectonic blocks. Therefore this contour can be displaced at least some 60 km southward, closer to the Aipe region into the Neiva Subbasin (i. e. southern Upper Magdalena Valley). That means the margin of the advancing sea was already in this region by that time. Fig. 5. Palynomorphs frorn sample LV-4, numbers in brackets indicate slide number (roman)and coordinates;reference points are: I = 54,9/117,8; I1 = 53,5/118,2;V = 55,6/119,6; V1 = 57,5/117,9. All magnifications are X 1000. 1,4: Lycopodiumsporites solidus BURGER 1980 (I 36,8/108,7). 2, 5: Monosulcites spinosus BRENNER 1.963 (I130,5/124,2). 3, 6, 10: Echinatisporis cf. varispinosus (POCOCK 1962) SRIVASTAVA 1977 (V1 39,9/119,2). 7-9: Neoraistrickia truncata (COOKSON 1953) POTONIE 1956 (I 27,6/124,1). 11 : Contignisporites cooksoniae (BALME 1957) DETTMANN 1963 (I 35,7/12 1,8). 12-13: Cicatricosisporites implexus Yu in MIAOet ai. 1984 (V 44,4/128,4). 14: Crybelosporitessp. A (I128,5/121,2). 15: Callialasporites trilobatus (BALME 1957) DEV1961 (I143,2/119).


Fig. 5 (Legend See p. 230)

23 1

232


Conclusions The Yavi Formation is a rock unit formed mostly by fluviatile regime, but with a detected marine episode. It reflects a positive morphology being peneplainized and conquered gradually by a transgressive sea. While sample LV-4 represents a terrestrial environment, some typically marine eiements are present in LV-5. Because of their rare occurrence the marine influence must have been sporadic. A fully marine environment is represented by the dinoflagellate association in sample LV-14, where terrestrial palynomorphs are scarce. For the studied area, the age of the Yavi Formation is proved to be Aptian, while the deposition of the lowermost Part of the Caballos Formation might have started during the latest Aptian. First hints of the Cretaceous transgression in the Neiva Subbasin of the Upper Magdalena Valley are evident in the younger Early Aptian. Biostratigraphic control to the Cretaceous paleogeography of Colombia is thereby provided.

Acknowledgements We thank the Ingeominas, Bogoti, for supporting the field work and the Deutsche Forschungsgemeinschaft (DFG, grant B1 66/10-1) for financing palynological investigations. The Deutsche Akademische Austauschdienst (DAAD, grant 322/509/002/1) is acknowledged for supporting further research in Germany. For laboratory preparation we thank Mrs. C. SCHMIDTand for photographical work Mrs. M. SCHORGE.Common field work with G. RENZONIis acknowledged, as well as critical reading by Prof. Dr. B. V. ADENIRAN and D. TANNER. F. STIBANE, Dr. J. R. GRÖSSER, Sedimentology is part of the second author's dissertation at the University of Gießen.

Literature ALLEN,J. R. L. (1970): Studies in fluviatile sedimentation: A comparison of finingupwards cyclothems, with special reference to coarse-menber composition and interpretation. - J. Sed. Pet., 40, (1): 298-323; Tulsa (Oklahoma). grains from the Mesozoic of Western Australia. BALME,B. E. (1957): Spores and Australia CSIRO, Coal Res. Sect., Tech. Comm., 25: 1-48; Chastwood/N.S.W.. BELTRAN,N . & GALLO,J. (1968): The Geology of the Neiva Sub-basin, Upper Magdalena Basin. - In: Geological Field Trips, Colombia. C.S.P.G.G.: 253-276; Bogoti. BRENNER, G. J. (1963): The spores and pollen of the Potomac Group of Maryland. Maryland Dept. Geol., Mines and Water Res., Bull., 27: I-IX, 1-215; Baltimore. BURGER,D. (1980): Palynology of the Lower Cretaceous in the Surat Basin. - Australia BMR Bull., 189: I-V, 1-106; Canberra.

Fig. 6. Palynomorphs from sample LV-4, numbers in brackets indicate slide number (roman) and coordinates; reference points are: I1 = 53,5/118,2; V1 = 57,5/117,9. All magnifications are X 1000. 1,4: Cicatricosisporitessp. cf. C. imbricatus (MARKOVA 1961) SINGH1971 (I1 39,9/122,8). 2-3, 5: Retimonocolpites sp. cf. R. reticulatus (BRENNER 1963) DOYLEin DOYLEet al. 1976 (V1 45,5/120,3). 6-7: Leptolepidites iwegularis (BRENNER 1963) WINGATE 1980 (I1 41,4/117,3).


Fig. 6 (Legend See p. 232)

233

234


Fig. 7 (Legend see p. 235)


235

BÜRGL,H. (1961): Geologia de los alrededores de Ortega, Tolima. - Boletin de Geologia U.I.S., 8: 21-38; Bucaramanga. COLLINSON, J. D. (1989): Alluvial Sediments. - In: READING,H. (ed.): Sedimentary environments and facies. Second Edition, Blackwell Scientific Publications: 20-62; Oxford. COOKSON, I. C. (1947): Plant microfossils from the lignites of Kerguelen Archipelago. BANZ Antarctic Res. Exp. 1929-1931, Rep., A-2 (8): 127-142; Adelaide. -,- (1953): Difference in microspore composition of some samples from a bore at Comaum, South Australia. - Australian J. Bot., 1 (3): 462-473; Adelaide. H. (1967): The Geology of the Upper Magdalena Basin (northern portion). CORRIGAN, In: Geological Field Trips, Colombia. C.S.P.G.G.: 221-252; Bogoti. COUPER,R. A. (1953): Upper Mesozoic and Cainozoic spores and pollen grains from New Zealand. - New Zealand Geol. Surv. Palaeontol. Bull., 22: 1-77; Lower Hutt. -,- (1958): British Mesozoic micospores and pollen grains. - Palaeontographica B, 103: 75-179; Stuttgart. DAILY,B., MOORE,P. S. & RUST,R. (1981): Terrestrial Marine Transition in the Cambrian rocks of Kangaroo Island, South Australia. - Sedimentology, 27 (4): 379-399; Abingdon (Oxfordshire). DAUGHERTY, L. H. (1941): The Upper Triassic flora of Arizona. - Carnegie Inst. Washington Publ., 526: 1-108; Washington. DAVIES,E. H . (1985): The Anemiacean, Schizaeacean and related spores: An index to genera and species. - Can. Tech. Rep. Hydrog. Ocean Sci., 67: 1-F45; Dartmouth (Nova Scotia). DEAK, M. H . (1964): Contribution i l'itude palynologique du Groupe d'Argiles ii Munieria de I'itage Aptien. - Acta Bot., Acad. Sci. Hung., 10: 95-126; Budapest. DELCOURT, A. F., DETTMANN, M. E. & HUGHES,N. F. (1963): Revision of some Lower Cretaceous microspores from Belgium. - Palaeontology, 6 : 292-292; London. G. (1955): Les spores et grains de pollen du Wealdien du DELCOURT, A. & SPRUMONT, Hinaut. - Mem. Soc. Beige Geol., Pal. et Hydrolog., N. S., 5: 1-73; Bruxelles. DETTMANN, M. E. (1963): Upper Mesozoic microfloras from South-Eastern Australia. R. Soc. Victoria. Proc., 77 (1): 1-148; Melbourne. DEV,S. (1961): The fossil flora of the Jalapur Series. - Palaeobotanist, 8: 43-56; Lucknow. DÖRING,H. (1965): Die sporenpaläontologische Gliederung des Wealden in Westmecklenburg - Geologie, Beih., 47: 1-118; Berlin. S. & DOERENKAMP, A. (1982): Afropollis, a new genus of early DOYLE,J. A., JARDINE, with notes on the Cretaceous palyno-stratigraphy and paleoangiosperm environments of Northern Gondwana. - Centres Rech. Explor. Prod. Elf-Aquitaine, 6 (1): 39-1 17; Pau. B. (1975): Observations on exine structure DOYLE,J. A., VANCAMPO,M. & LUGARDON, of Eucomiidites and Lower Cretaceous angiosperm pollen. - Pollen et Spores, 17 (3): 429-486; Paris.

Fig. 7. Palynomorphs from sample LV-5, numbers in brackets indicate slide number (roman) and coordinates; reference -points are: I = 55,5/117,8; I1 = 54,5/118,5; 111 = 57,2/118,6. All magnifications arex 1000. 1,3 : Cicatricosisporites potomacensis BRENNER 1963 (1 28/121,2). 2,4: Cicatricosisporites sp. cf. C. purbeckensis NORRIS1969 (I 29,3/121,8). 5: Uniserial foraminiferal inner lining g. et sp. indet. (11142,9/127). 6: Callialasporites turbatus (BALME 1957) SCHULZ1967) (I1 42,1/112,6).

236




237

ELLIOT,T. (1989): Siliciclastic Shorelines. - In: Reading, H. (ed.): Sedimentary environments and facies. Second Edition. Blackwell Scientific Publications: 155-188; Oxford. D. (1969): Contornos sucesivos del mar Creticeo ETAYO,F., RENZONI,G. & BARRERO, en Colombia. - I. Cong. Col. Geol. Mem.: 217-252; Bogoti. EYNON,R. & WALKER, R. (1974): Facies relationships in Pleistocene outwash gravels, southern Ontario: A model for bar growth in braided rivers. - Sedimentology, 21 (1): 43-70; Abingdon (Berkshire). FENSOME,R. A. (1987): Taxonomy and biostratigraphy of schizaealean spores from the Jurassic-Cretaceous boundary beds of the Aklavik Range, District of Mackenzie. - Palae~ntogra~hica Canadiana, 4: 1-49; Calgary. (Alberta). FILATOFF, J. & PRICE,P. L. (1988): A pteridacean Spore lineage in the Australian Mesozoic. - In: Jell, P. A. & Playford, G. (eds.): Palynological and palaeobotanical studies in honour of Basil E. Balme. - AAPG Mem., 5: 89-124; Sydney. FUQUEN, J., RODR~GUEZ, G. & COSSIO,U. (1989): Mapa Geologico Preliminar, Sheet 302 (Aipe). Sc: 1 :I00 000, Ingeominas; Bogoti. GUILLANDE,R. (1988): Evolution Meso-Cknozoique d'une vallke intercordilleraine Andine: la Haute Valley du rio Magdalena (Colombie). - These de Doctorat de l'universiti de Paris. GUY,D. J. E. (1971): Palynological investigations in the Middle Jurassic of the Vilhelmsfalt boring, Southern Sweden. - Inst. Min., Palaeontol. and Quat. Geol., Publ., 168: 1-104; Lund. HARMS, J. C., SOUTHARD, J. B. &WALKER, R. G. (1982): Structures and sequences in clastic rocks. - S.E.P.M., Short Course 9 (Calgary); Tulsa (Oklahoma). HEDLUND,R. W. (1966): Palynology of the Red Branch Member of the Woodbine Formation (Cenomanian), Bryan County, Oklahoma. - Okla. Geol. Surv., Bull., 112: 1-69; Norman (Oklahoma). HUNT,C. 0 . (1985): Miospores from the Portland Stone Formation and the lower Part of the Purbeck Formation (Upper Jurassic/Lower Cretaceous) from Dorset, England. - Pollen et Spores, 27 (3-4): 419-451, pl. 1-6, fig. 1-5; Paris. KRUTZSCH, W. (1959): Mikropaläontologische (sporenpaläontologische) Untersuchungen in der Braunkohle des Geiseltales. - Geologie, Beih., 21-22: 1-425; Berlin. MACERALLI, C. (1988): Cretaceous paleogeography and depositional cycles of Western South America. -J. South Am. Earth Sci., 1 (4): 373-418; Oxford. MAC~A, C., MOJICA,J. & COLMENARES, F. (1985): Consideraciones sobre la importancia de la paleogeografia y las ireas de aporte precreticicas en la prospeccion de hidrocarburos en el Valle Superior del Magdalena. - Geologia Colombiana, 14: 49-70; Bogoti.

Fig. 8. Palynomorphs from sample LV-5, numbers in brackets indicate slide number (roman) and coordinates; reference points are: I = 55,5/117,8; I1 = 54,5/118,5; I11 = 57,2/118,6. All magnifications are X 1000. 1,4: Zschyosporitespseudoreticulatus (COUPER1958) DÖRING1965 (I 34,2/108,1). 2,5: Afropollis sp.A DOYLEet al. 1982 (111 42,1/123). 3, 6: Nodosisporites sp. cf. N . dentimarginatus (BRENNER 63) DAVIES1985 (I1 36,4/116). g. et sp. indet. (111 44,5/129,1). 7,lO: Tricolporate 8 , l l : Zschyosporites foveolatus ( P o c o c ~1964) FENSOME 1987 (111 43,9/107). 9: Callialasporites minus (TRALAU1968) GUY1971 (111 49,9/116). 12: Concavissimisporites variverrucatus (COUPER1958) BRENNER1963 (111 47,5/107,6). 13: Zonasulculate pollen g. et sp. indet. (111 49,4/122,2).

238



The Yavi 'Formation, Upper Magdalena Valley

239

MARKOVA, L. G. (1961): Distribution of Schizaeaceae spores from the Cretaceous of the West Siberian lowland and their importance for stratigraphy. - In: K metodike paleopalinologicheskich isseledovanii: 214-226; Leningrad. [In Russian] models in braided river deposits: MIALL,A. D. (1978): Lithofacies types and vertical a Summary. In: MIALL,A. D. (ed.): Fluvial Sedimentology. - Can. Soc. Pet. Geol., Mem. 5: 597-604; Calgary (Alberta). MIAO,S., Yu, J., Qu, L., ZHANG,W., ZHANG,Q. & ZHANG,D. (1984): Mesozoic spores and pollen. - In: Paleontological Atlas of North China, 111. Mi~ro~aleontological Volume. - Tianjin Inst. Geol. Min. Res. 440-638: 710-725 (English Abstract); Tianjin. [In Chinese] MILEY,R. (1945): Gr.ological report on the Chaparral-Ortega Area. Unpubl. int. rept. Texas Petroleum Company. MOJICA,J. & MAC~A, C. (1981): Caracteristicas estratigrificas y edad de laFormaci6nYavi, Mesozoico, de la regi6n entre Prado y Dolores, Tolima, Colombia. - Geologia Colombiana 12: 7-32; Bogoti. NORRIS,G. (1968): Plant microfossils from the Hawks Breccia, south-west Nelson, New Zealand. - N.Z. J. Geol. Geophys., 11 (2): 312-344; Wellington. -,- (1969): Miospores from the Purbeck Beds and marine Upper Jurassic of southern England. - Palaeontology, 12 (4): 574-620; London. North American Commission on Stratigraphic Nomenclature (1983): North Arnerican Stratigraphie Code. - A.A.P.G. Bull., 67 (5): 841-875; Tulsa (Oklahoma). PIERCE,L. (1961): Lower Upper Cretaceous plant microfossils from Minnesota. Minnesota Geol. Surv., Bull., 42: 1-86; St. Paul (Minnesota). P o c o c ~S. , A. J. (1962): Micofloral analyses and age determination of strata at the JurassicCretaceous boundary in the Western Canada ~ l a i n s . Palaeontographica, B. 111: 1-95; Stuttgart. -,- (1964): Pollen and spores of the Chlamydospermidae and Schizaeaceae from Upper Mannville strata of the Saskatoon area of Saskatchewan. - Grana Palynologica, 5 (2): 129-209; Stockholm. PONS,D. (1982): Decouverte du Cretace moyen sur le flanc est du Massif de Quetame, Colombie. - C. R. Acad. Sc. Paris, 294: 533-536; Paris. POTONIE,R. (1956): Synopsis der Gattungen der Sporae dis~ersae.I. Teil - Sporites. Geol. Jb., Beih., 23: 1-103; Hannover. POTONIE,R. & GELLETICH, J. (1933): Uber Pteridophyten-Sporen einer eozänen Braunkohle aus Dorog in Ungarn. - Berl. Ges. Naturforsch. Freunde, Sitzungsber. (1932), 33: 517-528; Berlin.

Fig. 9. Palynomorphs from sample LV-5, numbers in brackets indicate slide number (roman) and coordinates; reference points are: 111 = 55,5/117,8; IV = 52/119; V = 56,21118,6. All magnifications are X 750. Fig. 9.17 is from sampie LV-14, X 1000 (See bar above Fig. 9.16). 1-2: Acritarch g. et sp. indet. (V 33,7/124,5). 3-4: Is~h~osporites aveolatus (SINGH1971) FENSOME 1987 (V 48,2/111,7). 5,8,9: Lycopodiumsporites dentimuratus BRENNER 1963 (IV 28,6/126,5). 6-7: Cicatricosisporites ludbrookiae DETTMANN 1963 (V 46,411 13,3). 10,14: Iscbyosporites variegatus (COUPER1958) SCHULZ1967 (I11 35/129,6). 11-12: Ecbinatispovis vanspinosus ( P o c o c ~1962) SRIVASTAVA 1977 (IV 25,3/125). 13,15: Iscbyosporites cf. variegatus (V 32,1/107,4). 16: Cicatncosisporitespotomacensis BRENNER 1963 (V 34,1/116,9). 17: Equisetosporites ambiguus (HEDLUND 1966) SINGH1983 (LV-14; I 41,1/114).

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K. F. Prössl and L. Vergara Streinesberger, The Yavi Formation

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