AMEGHINIANA ISSN 0002-7014 Revista de la Asociación Paleontológica Argentina Tomo XII Diciembre de 1975 N?4 THE INDO-PACIFIC AMMONITE MAY AITES IN THE OXFORDIAN OF THESOUTHERN ANDES By P. N. STIPANICIC', G. E. G. WESTERMANN 2 and A. C. RJCCARDI3 ABSTRACT: Oxfordian Iitho- and biostratigraphy of the Chilean and Argentine Andes is reviewed (P. N. Stipanicic). Within the Chacay Group, the Lower to basal Upper Oxfordian La Manga Formation, below, mostly detrital and biogenic, and the Upper Oxfordian Au- quilco Formation, above, mainly chemical, are distinguished. The La Manga Formation (with Gryphaea calceola lumachelle) is rich in ammonite faunas, particularly of thc upper Cordatum to lower Canaliculatum Zones. In Neuquén and Mendoza provinces of Argentina, the Pli- catilis Zone or Middle Oxfordian has yielded Perísphinctes spp., Euaspidoceras spp., Aspido- ceras spp., together with Mayaítes (Araucanites ) stípanícfcí, M. (A.) reyesi, and M. (A.) mulai, Westermann et Riccardi subgen. et spp. nov. The first find of Mayaitidae outside the Indo-Pacific province is discussed in light of _plate-tectonic theory. RESUMEN: La revisron Iito- y bioestratigráfica del Oxfordiano de los Andes de Argentina y Chile (P. N. Stipanicic) ha permitido reconocer dentro del Grupo Chacay: 1) abajo, la Formación La Manga, mayormente detrítica y biogénica, del Oxfordiano inferior-superior basa!, y 2) arriba, la Formación Auquilco, mayormente química, del Oxfordiano superior. La For- mación La Manga (con lumachelas de Gryphaea calceola) contiene abundante cantidad de amonitas, particularmente de las Zonas de Cordatum superior a Canaliculatum inferior. En las provincias de Mendoza y Neuquén,Argentina, la Zona de Plicatilis (Oxfordiano medio) contiene Perispbinctes spp., Euaspidoceras spp., Aspidoceras spp., conjuntamente con Mayaites (Araucanites) stipanicici, M. (A.) reyesi, y M. (A.) mulai, Westermann et Riccardi subgen. et spp. nov. El primer hallazgo de Mayaitidae fuera de la provincia lndo-Pacífica es dis- cutido tomando en consideración la teoría de tectónica de placas. · P·¡¿Ó•¡ e¡·•o¡l ¿ÓS•Ón·•¡ Ón Só¿°¡7 a·¡l =BFC5 RÓnos P•Ós5 PñÓ•¡7 • Department of Geology, Md1aster Univorsity, Hamilton , Ontario, Canadi •. !l ~Juseo ¿Ó S•Ón·•¡s Naturales, c¡ gl¡t¡5 PrñÓnt•n¡7 ~ 281- THE OXFORDIAN cipal Gypsum" (Schiller, 1912); in Chile OF THE ANDEAN GEOSYNCLINE as Millonaria Formation (Harrington, OF ARGENTINA AND CHILE 1961), Middle Member of the Laguni- llas Forma tion (Aguirre Le Bert, 1960), By P. N. STIPANICIC Midd1e Member of the Valle Grande Formation (Gonzalez and Vergara, 1964), 1. LITHOSTRATIGRAPHY Rio Colina Formation (Gonzalez, 1963), Santa Elena Member of the Nacientes del Oxfordian is well represented within Teno Forrnation (K10hn Giehm, 1960), the Argentine and Chilean part of the and others. Mesozoic Andean Geosyncline where it The lower unit, although showing mi- forms part of the Chacay Group t sensu nar facies variation and varying in thick- Stipanicic and Mingramm in Groeber, ness from O to 220 m, was named La 1951 ), belonging to the Chacayano se- Manga Formation (Stipanicic and Min- dimentary cycle (Groeber, Stipanicic and gramm in Groeber, 1951 ,as "Manguen- Mingramm, 1953). The base is marked se"; Stipanicic, 1966). Formerly known by a disconformity or unconformity (Río as "blue limestones with Grypbaea" Grande Phase) with Oxfordian directly (Groeber, 1929), the formation appears overlying Bajocian to Middle Callovian 111 outcrop superficially homogeneous beds; Upper Callovian appears to be with brownish-bluish-gray weathering missing in the entire basin except in the colour. Two main 1ithofacies can be dis- Domeyko mountain range (Hillebrandt, tinguished: (a) a nearsbore facies of thick 1970). The Chacay Group is, in turn, un- hard limestones, sometimes arenaceous, conformably overlain (Araucan Phase) by dark grayish weathering b1uish-gray, with Lower to Upper Kimmeridgian or even cora1s, 1umachelle of Gryphaea calceoia Tithonian (Stipanicic, 1966, 1969; Stipa- ( Qu.) and scarce ammonites; and (b ) nicic and Rodrigo, 1970). a standard facies,above with bluish-gray The Chaca y Group is divided into two Iimestone with minimal amounts of clas- distinct but intergrading sedimentary units, tic, intergrading upwards into the Auquil- i.e., the lower one is mostly detrital and co Formation by increased interbedding biogenic belonging to the Lower to basal of gypsum, with scarce ammonites, and Upper Oxfordian; the upper one, mainly below predominant1y brownish-gray silts- chemical, belongs to the Upper Oxfor- tone, shales, calcilutite and oolites, with dian. The upper unit has unusual facies more abundant ammonites (Groeber et. homogeneity from 18° S in northern Chi- al., 1953; Stipanicic, 1966). le to 39° S in Neuquén province, consis- The standard facies has been identi- ting of up to 400 m of gypsum and/or fied in the subsurface of Neuquén pro- anhydrite and interbedded stinking whitish vince (named Barda Negra Formation, 1imestones in different proportions. In Digregorio, 1965). In Chile, synchronic Argentina, this unit is known as the sediments in similar facies were given a Auquilco Formation (Weaver, 1931; number of formatianal names (Cecioni Groeber, 1946), formerly also as "Prín- and Garcia, 1960 a, b; Galli and Ding- - 282- 70° \ SANTIAGO. / - TUPUNGATO - TUNUYAN I í I \k/o--Col-ino I ---34° RANCAGUA _ ! {¿\ - I A SAN RAFAEL t!¡/! 't0 Blonco R/o O,amant.- CURICÓ !.~ T t Aa di Monqo .,1 _ l· R/o Choicos . O ~\ R/o reno. S.onlo Elehol ' •'¡' •• ,.,_0<',-".," _~~~ '" ,,, c.,,, ' TALCA - R/a \ ~I ~.~rgüe "'0 ~ Mf Ossto v/ti> \ • Ows vw lo g·ryw I I -------36° ! CHILLAN. Aquada de Campos X (Sierra de Reyes) X Aquodo de lo Mulo Veqo de lo Veranodo LOS ANGELES R¡'O • J -f'''ó <9. ~o \ .6. Main localities with Oxfordian faunos X Id.• with Movoitidoe o 50 t\\• I 6464 4 NEUQUEN. Fig. 1. - Importaut Oxfordiao local il.ies, inelnding those wiLh Mayaites (Araucanites) sul-gen . ·eL spp. nov., in ArgenLina and Chile between latitudes 33° and 3908 (eL Sti panicic , 11)66) - 283- man 1962' Harrington, 1961; Klohn or Plicatilis Zones, but only Plicatilis mrnm, lJ~m.Jm lwm ij~~m~~~r~ ~illl~mm l~m)1 nlmlll~ facies in northern Chile to standard fa- Zone and possibly part of the Cordatum cies, often with andesite flows, in the Zone seems more probable. The upper central latitudes: i.e. Tarros Fm., Chacari- beds, with Gregoryceras toucasianum 11a Fm.,Upper Agua Santa Fm., Dorali- (d'Orb.), G. d. transuersarium (Qu.) , sa Fm., and Upper Rinconada Member Ocbetoceras hispidum (Opp.), Perispbinc- of the Nacientes del Teno Formation, etc. tes (Arisphinctes?) andium Stein., P. (A.?) boebmi Stein., P. (A.?) gleimi 2. BIOSTRATIGRAPHY AND BIOCHRONO- Stein., Mirosphinctes sp., and Euaspi- LOGY OF THE LA MANGA FORMATION. doceras d. perarmatum (Sow.), were placed in the Transversarium Zone (Hil- The La Manga equivalents in northern lebrandt, 1970). The lower Bimam- Chile have yielded airich fauna of the matum Zone is indicated by Decipia (?) Plicatilis and Canaliculatum Zones (Mi- gottschei (Stein.}, Discosphinctes d. lu- ddle and lower Upper Oxfordian) at - cingae (Favre) and Euaspidoceras d. Caracoles (Steinmann, 1881; Stehn, 1923; '. perarmatum, while the upper part of the Leanza, 1947 a) including Ochetoceras zone is indicated b~ Decipia (?) deser- canaliculatum (v. Buch), Trimarginites torum (Stehn), Ocbetoceras d. bispi- arolicus (Opp.), Euaspidoceras d. perar- dum (Opp.}, Campylites d. mexicanus matum (Sow.), E. cbilense Leanza, Pe- (Burckh. ), Euaspidoceras sp. and 1doce- risphinctes healeyi (Neum.) P. andium ras sp. (Hillebrandt, 1970). However, Stein., P. (Arisphinctes) barringtoni several species of the last two assembla- Leanza. A very similar fauna occurs ges are already known from the Canali- further north at Arica, together with culatum and even Pliea tilis Zones of doubtful Progeronia which would indica- Europe (Arkell, 1956; Enay et al., 1974). te Lower Kimmeridgian ( Cecioni and Further south in Chile and Argentina, Garcia, 1960 a, b; Corvalan, 1965; Salas the La Manga Formation ("Manguenses" et al., 1966). Faunal lists of partially beds ) was long regarded as Callovian mixed Middle Callovian and Oxfordian (Groeber, 1918, 1929, 1933; Gerth, faunas from the Santa Ana Formation of 1925; Larnbert, 1956), in spite of some pa- Negreiros (Cecioni and Garcia, 1960 o; laeontological evidence suggesting Oxfor- Cecioni, 1961) need to be reexamined. dian. The small poorly preserved assernbla- In general, the northern Chilean faunas ge from the Santa Elena Region (Iocality appear to be mainly Middle Oxfordian. 19) originally described by Burckhardt In the Domeyko Mountains, 25-26° S, (1900 a) as Athleta Zone and later the lower La Manga equivalents yielded (Burckhardt, 1903) reclassified and dated Gregoryceras (Pseudogregoryceras ) d. Callovian-Oxfordian boundary of Mariae iteni (Jeannet), Campylites (Neopriono- Zone (Spath, 1931), needs to be enlar- ceras) d. benrici (d'Orb.) and Peris- ged and reexamined; the alleged Quens- phinctidae which Hillebrandt (1970) on tedtoceras C'Cardioceras aff. lamberti") page 192 considered to represent Lamberti could be a crushed macrocephalitid accor- - 284- SIERRA DE REYES EÜROPEAN ZONES VEGA DE LA VERANADA STAGES (Neuquén) ( Mandozo) viroatosoninct es Ironsilorius Fm, MUERTA Fm .. TlHioNIAN VACA MUERTA VA CA } Severa I z on e s ( s 1,) Virqalosphineles Gravesia qravesiana Hybonolieeros oeck er t KIMMERIDGE a atocost, p s eu aomut ab is (s. str.} Strebliles {SIr. teno it. s. sir, lenuilob,atus Sut n, p ta ty not a Idoeeras {Sulneria qalar Ir UJ planula 51· Idoe.plan. s,slr. e, z e, Epipeltoeeras bimammolum « ::> Perisphineles· mor t eüi> Ocñetoc er as eanolieulalum o Pe/toeeras Pejloeeras, Euospidoeeras « el:: Pe/loeeros, Euaspidoc eras, ;; C> O Perisphinel (Kranoospl¡ineles) ~ Perisph, (Arisphineles) z .. u, ci Perisphinetes pliealilis « c Mayailes (Aroueon/les l sp. KKKLlm88 1\..) P (Prososphineles) :::¡; X ex> '" Mayailes ( ar ouconites ) sp. [ M. (A) mu tai, M. (A) r.ey es¡ « Vl O M. (A) sl/panieiei ..J ~ Cardioeeras cordatum o -' Ouens tedt ocer as mariae o.: Ouens te d toc er os tamb er t¡ z ::> Pel/oeeros attitet o « o Erymnoceros coronatum > Kosmoeeros ja s on O ...J '" ...J Ir Maeroeephaliles .