Ostracods and foraminifera from the Early - Middle Eocene of Qeren Sartaba, Jordan Valley

23 species of ostracods and 20 species and species groups of planktonic foraminifera from the 80m thick Qeren Sartabasection, central Jordan Valley, are described and illustrated. The material is determined by planktonic foraminiferal biostratigraphy to belong to the latest Early Eocene (upper part of Zone P9) and the early Middle Eocene (Zone P10). The palaeoecology is representative of a pelagic marine shelf, with periodic events of shallowing and hardground formation.


INTRODUCTION AND GEOLOGICAL SETTING
The Eocene section in. the Qeren Sartaba region, central Jordan Valley, eastern Samaria ( Fig.1) was mapped and described by Benjamini (1973). This marine sequence is characterized by chalk, chert and limestone lithologies. Shallow water limestones with larger foraminifera interfinger with more pelagic, chalky lithofacies in a complex pattern, but generally trending towards pelagic predominance southwards. Part of the palaeotopography of the Eocene substrate was derived from Cretaceous tectonics (Mimran, 1984), but much resulted from intra-Eocene folding and normal faulting. Two important angular unconformities, in the late Early Eocene and the mid-Middle Eocene part of the section, are tangible evidence of this structural activity. Biostratigraphic dating of the sedimentary and structural events was by planktonic foraminifera from the chalky facies, and this material has to date not been published.
The Sartaba Member of the Matred Formation (note: lithostratigraphic nomenclature in this area is tentative and unpublished, following broadly names used in the northern Negev, southern Israel) contains an important chalk horizon with a rich assemblage of planktonic foraminifera and ostracods, characteristic of the Early -Middle Eocene transition. The section described here is located at coordinates 1937/1668 (Israeli grid), a few hundred metres south of the archaeological site of Qeren Sartaba. An additional section, approximately one kilometre west of the Sartaba section at A 278 (coordinates 1925/1666). The location of these sections is shown in Fig.1. Samples from the chalky horizons were taken approximately every three metres.
The Sartaba Member at the Qeren Sartaba section is 80m thick, and consists of chalk and fine-grained limestone (Fig.2). The formation commences with the first chalk above the limestone Masua Member, and rapidly becomes a massive chalk, punctuated by some limestone hardgrounds. There is some limonite staining. At the interval from 50-65m. round nodules containing barite are present in the chalk. At 6Sm above the base, fine-grained limestone with chalky interbeds again predominates, and the section is truncated by an angular unconformity at 80m. At the location at A 278, the section is l l O m thick, with the additional section attributable to less truncation beneath the unconformity, as the lower subunits are identical with those of the Rare macrofossils in the chalk include small. branching (probably ahermatypic) hexacorals. a scaphopod. lucinid and cardiid bivalves, a cerithiid gastropod. and teeth of Lanmr. Thin sections show the chalky facies to be a pelagic biomicrite, with abundant p I an k t o n i c foraminifera and rare radio 1 ar i an s . Phosphatic fragments are not uncommon. The limestone horizons    are mostly similar, but with more evidence of bioturbation and thus probably indurated hardgrounds of the chalky facies. Ammohaculites sp. is common in the hardgrounds. At location A 278, a hardground horizon at 35m is colonized by a nummulitic fauna, echinid and bryozoan debris, and rhodophyceans. This fauna was not recovered from hardgrounds at this level at the Sartaba section. The limestones at the top of the Sartaba Member contain, in addition to bioturbated pelagic material, transported fragments of rotaliid larger foraminifera, foretelling a significant shallowing trend. No clastics were found in thin sections.
The palaeoenvironmental interpretation based also on field and petrographic studies is a deep neritic, subphotic shelf dominated by pelagic facies, interrupted a t intervals by hardground formation. At least one of these bears evidence locally of shallowing into the photic zone. Water depths of 50-1 50m, of normal salinity, and relatively warm temperatures are thus indicated.
In this paper we describe an ostracod and foraminifera1 faunule found at the Qeren Sartaba section.
Common to abundant ostracod faunas were found in the Sartaba Member at Qeren Sartaba in nearly all samples of the lower and middle part of the Sartaba Member (CB200 -219). Richest in ostracods are the samples CB 215 -218 from the middle part of the section. The ostracods are figured on PIS 1-2, and their distribution is given on Fig.2.

TAXONOMY
All the examined and described ostracods are deposited in the collection of the Geological S u r v e y of Israel. T h e abbreviations 1, h, w in this chapter refer to length, height and width of the representative types and M, F to male and female specimens, respectively.  Cronin, 1978). The surface of the carapace is entirely covered with small and dense pits. The eye-spot is oval and weakly developed. The valves are denticulated zntero-and posteroventrally. Our specimens resemble in these features the figured type of Bair-dia ilarnensis Reyment & Reyment, 1959in Bassiouni & Luger (1990. 1, fig. 15; Maastrichtian -Early Eocene of Egypt).

Remarks. The generic position of these specimens as species of
Parakrithe must remain open, until single valves will be found and their marginal pore canals can be examined. The broadly rounded posterior end is characteristic for the small carapaces of Parakrithe? sp. Similar types of Parakrithe are also commonly found in Late Paleocene -Middle Eocene strata of Egypt (Cronin & Khalifa, 1979;Bassiouni & Luger, 1990;Ismail A . and Szczechura, pers. comm., 1989 Remarks. This small form of Xestoleberis possesses a rounded anterior end, pointed ventrally, and shows an angular posterodorsal margin. The posterior margin is only slightly rounded to truncated. Xestoleberis kenawayi was described originally from the Middle Eocene sediments of Egypt (Khalifa & Cronin, 1978). It differs from other Middle Eocene species of this genus mainly by its less rounded posterior end (X. subglubosa (Bosquet), 1852 in Boukhary et al., 1982b, p1.2, fig.11;and in Bassiouni et al., 1984, p.186, p1.2, fig.8). Our specimens are also very similar to X. kiseibaensis Bassiouni & Luger, 1990 (p.848, p1.25, figs 8-12; Maastrichtian -Early Eocene of Egypt), but exhibits a less convex dorsal margin.

Explanation of Plate 2
Pterygocythereis sp.. Ieft (Bassiouni, 1969a). This species exhibits in other sections in Israel a relatively broad stratigraphic range, but is most common here in this Early -Middle Eocene transition interval.

Explanation of Plate 3
If not otherwise indicated, the scale on Fig. 3 implies for all Figures. Fig. 13. Fig. 1.
"Glohigcvina" .sp, spiral view, CB 21 8. Fig. 2 1,   Fig. I 1, "Glohigrrinu" sp., umbilical view. CB 21 8. Fig. 12. "Glohi,yerina" sp., axial view, CB 218. Fig. 22. Remarks. The rare occurrence of this species in the Sartaba section and the lack of information of its internal features do not allow its final definition as a probably new species of the genus Acanthocythereis. The specimens are finely reticulated, mostly in their central area, and possess low tubercles. The anterior and posterior areas are smooth. A ventral rib is composed of a chain of small nodes.

Remarks.
Reticulina with fine reticulation. Many small spines occur on the junction of reticulation ribs. A transversal oblique distinct ridge, mainly built by tubercles, starts from the very prominent eye spot and continues towards the ventral margin. Reticulina proteros was hitherto recorded only from Late Paleocene -Early Eocene sediments of Jordan (Bassiouni, 1 969b), Egypt (Bassiouni & Luger, 1990) and Tunisia (Donze et al., 1982). The figured specimens from Tunisia are less spinous than our material. Bassiouni, 1969 (PI. 2, fig. 8

Remarks.
Reticulina praescitula is similar to R. proteros, but differs from it by its less spinous ornamentation, less prominent eye-spot, coarser reticulation and the more developed longitudinal riblets. This species was found in Middle Eocene strata of Jordan (Bassiouni, 1969b) and Egypt (Bassiouni, 1969c;Ismail A. & Szczechura, pers. comm., 1989). Genus Ordoniya Al-Sheikhly, 1985 Genus Reymenticosta Bassiouni & Luger, 1990 Ordoniya hasaensis (Bassiouni), 1971(Pl. 2, fig. 5) 1971 Hazelina hasaensis Bassiouni (1971b) Remarks. The size, shape and rib pattern of our specimens agree well with the type-species and justify its definition as Ordoniya hasaensis. The range of this species, originally described from the Late Paleocene -Early Eocene of Jordan (Bassiouni, 1971b) is here extended to the early Middle Eocene. This species is found in Egypt in Early Eocene sediments (Ismail A. and Szczechura, pers. comm., 1989).
PLANKTONIC FORAMINIFERA (C. Benjamini) Well-preserved microfaunas were recovered from samples CB 207 -218, from the middle chalky part of the unit. Chalk from between the limestone interbeds contained recrystallized material from which only benthic foraminifera were recovered. Nomenclature of the planktonic foraminifera follows that of Benjamini (1980), for similar intervals in the northern Negev, and generally, usage in Toumarkine & Luterbacher (1985). Fig.3 shows the distrubution of the planktonic foraminifera in the chalky lithofacies of the Sartaba Member. Some of the species are illustrated on P1 3.
The following species are common at Qeren Sartaba. Only a brief discussion of special features is here presented. These are included to clarify our biostratigraphic conclusions.
Acarinina aspensis (Colom)/pentacamerata (Subbotina) IP1.3, fig.61. Benjamini (1980) ranged these two forms together. In the Qeren Sartaba material. The A. aspensis morphotype is clearly dominant. This very small form superficially resembles A . spinuloinflata, but the aperture is nearly in a globigerinid position and i t is very spinose. It may be more closely related to A. broedermanni. It was also found in the Negev. The affinity of this species is highly problematic. It has a subspherical test, and unlike "Sphaeroidinellopsis" senni, has a clearly defined, rather high early trochospire. In that respect it5 closest affinities are to some Globigerinatheka, but does not have an embrancing final chamber or bulla. The spire, test shape, and position of the single aperture strongly suggest affinity with Globigerinatheka index (Finlay) (gp.). It cannot be placed there as it lacks the requirements of that genus, but seems to be ancestral to that group.