Rodent Palaeoecology of the Continental Upper Miocene of Crevillente (Alicante, SE Spain)
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Palaeogeography, Palaeoclimatology, Palaeoecology 165 (2001) 349–356 www.elsevier.nl/locate/palaeo Rodent palaeoecology of the Continental Upper Miocene of Crevillente (Alicante, SE Spain) Elvira Martı´n-Sua´rez a,*, Matthijs Freudenthal a,b, Jorge Civis c a Departamento de Estratigrafı´a y Paleontologia, Universidad de Granada, 18071 Granada, Spain b Nationaal Natuurhistorisch Museum, Postbus 9517, 2300 RA Leiden, The Netherlands c Departamento de Geologia, Universidad de Salamanca, Salamanca, Spain Received 15 November 1999; accepted for publication 19 July 2000 Abstract The Upper Miocene succession of Crevillente presents an alternation of continental and marine beds. The marine fossils have been studied in order to obtain a reliable correlation with other marine sections. On the basis of these data, the entire section can be dated as Upper Tortonian/Messinian. The alternation of continental and marine beds fits the known eustatic sea-level and climatic curves. These correlations are used to assign ecological preferences to the components of the micromammal faunas at species level; it becomes clear that working at the genus level does not provide valid results. With the assignments, it is possible to demonstrate consistent climatic diVerences between the coastal plain of Crevillente and the area of Teruel on the Meseta of Central Spain. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Messinian; Miocene; palaeoecology; Rodentia; Spain 1. Introduction of the succession in order to achieve a dating, and we have tied it in with the eustatic sea-level curve. The area studied is located north of the village This gives us a correlation between the intercalated of Crevillente (province of Alicante), as indicated micromammal localities and the eustatic curve, in Fig. 1. The sedimentary succession under study which permits a climatological interpretation of lies unconformably on the Mesozoic substratum the mammalian faunas. and consists of alternating continental and marine beds (Freudenthal et al., 1991;Martı´n-Sua´rez and Freudenthal, 1998). Towards the north, the depos- its are slightly inclined, and towards the south, 2. Age of the continental deposits they are folded with inclinations of up to 60° SSE. The marine and brackish deposits contain fora- The relative dating of the continental deposits minifera and ostracods, and the continental depos- has been carried out by various authors, most its have yielded a number of fossil mammal recently by Martı´n-Sua´rez and Freudenthal, (1998). localities. We have studied the marine fossil content The mammal-bearing localities are mainly located in the sections A–A∞ and B–B∞ of Fig. 1. The * Corresponding author. Fax: +34-58-243203. locality Crevillente 2 (CR2), the oldest mammal E-mail address: [email protected] (E. Martı´n-Sua´rez) locality of the succession, is the reference locality 0031-0182/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved. PII: S0031-0182(00)00170-X 350 E. Martı´n-Sua´rez et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 165 (2001) 349–356 3. Age of the marine deposits The study of the marine deposits presents some problems, since most of the samples contain reworked foraminifera, mainly from the Cretaceous and the Paleogene. Two samples have given useful results. In the lowermost part of the succession, 60 m below CR2, the sample CRF-13, has turned out to be poor in planktonic foraminifera, among which have been distinguished Globigerina bul- loides, Globigerinoides obliquus, Globorotalia pseu- dobesa, Globorotalia gr. menardii (sinistral ), Neogloboquadrina acostaensis (sinistral ), Orbulina Fig. 1. Map of the Crevillente area. universa, Globoquadrina dehiscens. The presence of N. acostaensis (sinistral ) and G. menardii (sinis- of the Neogene mammal unit MN 11 (Mein, tral ), though scarce, permits a dating as Late 1990). The locality CR15 may be correlated Tortonian. G. menardii has not yet been replaced biostratigraphically with Los Mansuetos, strato- by the dextral form, which means that the deposits type of the Turolian, and reference locality of unit do not belong to the latest Tortonian. MN12. The locality CR6, the youngest of the In the highest part of the succession, between the succession may be correlated with El Arquillo 3, two reef episodes (Fig. 2), the sample CR14-F3 has which is the reference locality of unit MN 13 yielded benthonic foraminifera, which indicate a very (Mein, 1990). Thus, the continental deposits in shallow environment (Ammonia becardii, Elphidium the area cover most of the Turolian. For a biostrat- macellum, Asterigerinata planorbis, Lobatula lobatula, igraphical zonation, see Martı´n-Sua´rez and Nonion boueanum, Cribononion sp.; other, poorly Freudenthal (1998). represented, forms are Elphidium aculeatum, Fig. 2. Correlation of the mammal localities of Crevillente with those of Teruel, and with the eustatic sea-level curve of Haq (1991) and Brachert et al. (1996). The vertical scale of the eustatic curve is distorted, because it is adapted to an even distribution of the mammal localities. For locality codes, see the caption of Fig. 3. : regression; ÷: transgression; yy: reefs; nn: gypsum. E. Martı´n-Sua´rez et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 165 (2001) 349–356 351 Uvigerina sp. and Reussella spinulosa). Planktonic 1989) and with the Granada Basin (Braga et al., foraminifera are scarce: Globoquadrina cf. dehiscens, 1990). They correspond to the eustatic maximum Globigerinoides obliquus, Globigerina bulloides, Globi- of cycle TB 3.2 of Haq (1991). gerina sp., Globorotalia cf. mayeri and Globorotalia The next set of strata, containing the mammal gr. miotumida.TheGloborotalia miotumida group is localities CR2 to CR18, represents the transition understood as defined by Sierro et al. (1993), and to dominantly continental sedimentation, after the the forms present correspond to morphotype G. eustatic maximum of TB 3.2. conomiozea. From these data, its level can be attrib- The next span of the succession contains uted to the Messinian, to the replacement of fundamentally continental deposits, with several Globorotalia menardii by the group Globorotalia mio- mammal localities (CR8, CR7, CR17). The micro- tumida (G. menardii has not been found). fossils of these levels comprise some fragments of stems and gyrogonites of Charophyta. The associa- Thus, the marine beds correlate to the final % Tortonian and the Messinian. Fig. 2 gives the tion of ostracods tends to be monospecific: 90 belongs to Cyprideis torosa with practically smooth relative datings of the succession, both for conti- shells, suggesting a high calcium content in the nental and marine levels, as well as the correlations Mg/Ca ionic equilibrium. This indicates cold con- between these datings. ditions that appear to correspond to the regressive episode of cycle TB 3.3, which, in other basins, is represented by the deposition of bryomol calcirud- 4. Correlations with the eustatic curve ites (Brachert et al., 1996). The eustatic maximum of this cycle is repre- In the Upper Neogene of the SE part of the sented by two reefs that correspond to the Early Iberian Peninsula, six episodes of reef growth have Messinian reef episode in other Neogene basins of been identified, alternating with deposition of calci- SE Spain, like Sorbas, Cabo de Gata and Nı´jar. rudites (Brachert et al., 1996). The reef deposits, Their build-up took place during a transgression, indicating relatively high temperature, can be corre- which was correlated by Brachert et al. (1996) lated to sea-level highstands in the eustatic sea-level with the eustatic maximum of cycle TB 3.3 of the curve of Haq (1991), and the bryomol carbonates, global sea-level chart of Haq et al. (1988, 1991). that indicate lower temperature, correspond to sea- Cycle TB 3.4 begins with a regression that level lowstands. These sea-level variations in the coincides with the deposition of the gypsum in the Late Neogene are linked to glacial phenomena, Sorbas Basin (Martı´n and Braga, 1994) and the low-stands and high-stands correlating with cold calcarenites of Cabo de Gata (van de Poel et al., and warm phases, respectively, depending on the 1984). In Crevillente, it results in an unconformity amount of water stored in glaciers. on top of the reefs. The next transgression leads Three of the reef phases are dated as earliest to the development of more reefs in the Sorbas Late Tortonian, Early Messinian, and latest Basin (Martı´n and Braga, 1994) and Cabo de Messinian, respectively, and correspond to the Gata (Martı´n et al., 1993; Brachert et al., 1996). highstands TB 3.2, TB 3.3, and TB 3.4 of Haq In Crevillente, the sedimentation during this trans- (Brachert et al., 1996). gression is first continental (CR6) and later The deposits of Crevillente were formed in more becomes marine. The succession is unconformably shallow conditions than the sections studied by overlain by a thick succession of supposedly Brachert et al. (1996), and therefore, the cyclicity Pliocene conglomerates. is expressed as an alternation of marine and conti- nental deposits. In the oldest, marine, deposits of Crevillente, 5. Paleoecology we have found Neogloboquadrina acostaensis and 5.1. Ecological preferences per taxon Globorotalia menardii (sinistral ), which permit a correlation with the Sorbas Basin (Martı´n and The basis for the assignment of preferences to Braga, 1994), with Almanzora (Martı´n et al., the mammal species found is the correlation of 352 E. Martı´n-Sua´rez et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 165 (2001) 349–356 our Crevillente succession with the eustatic sea- is probably a vicariant descendant of A. barbarae; level curve and the corresponding temperature their co-existence in CR8 means that the speciation curve (Fig. 2). Species found in localities corre- must have taken place in another area and that A. lated with eustatic maxima are assigned a meini in CR8 is an immigrant. Thus, A. meini and warm/humid preference, and species from localities its ancestor A. barbarae may have had diVerent in eustatic minima are assigned a cold/dry ecological preferences (Vrba, 1980).