UTRECHT MICROPALEONTOLOGICAL BUllETINS

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drites are trace-fossils consisting of a system of regularly branching tunnels of uniform diameter, formed by some animal working from a fixed basepoint at or just below the seafloor. It is a cosmopolitan genus, reported with certainty from the Ordovicium to the Tertiary. Our Trubi specimens show a layered, carbonate filling which is more indurated and of lighter colour than the surrounding sediment. Preferential induration of such tunnel fillings has been noted before by Kennedy (1970). The entire genus Chondrites undoubtedly belongs to the Fodichnia and has to be regarded as feeding structures of sediment-eating animals and not as dwelling burrows of filter-feeding annelids (Seilacher, 1964). Simpson regards these burrows as the result of sipunculoid (= unsegmented) worms working from a fixed centre at the surface of the sediment and producing tunnels by an extensile proboscis; the branching pattern may be caused by phobotaxis (= behaviour to avoid penetrating its own tunnel or the tunnel of others in its passage through the sediment). A bed with Chondrites is of marine origin and the water was not greatly agitated by wave-action (Simpson, 1957, p. 494). Warme et al. (1973) stated that Chondrites has little value as a bathymetric indicator, being cosmopolitan and crossing both bathymetric and lithologic facies boundaries. But the presence of this trace fossil requires that the bottom waters be oxygenated when the traces were formed, and that the sediments contain sufficient food. The middle part of the Trubi in section 4 with its well-bedded appearance resembles the lower part of the Trubi on top of the basal 6 to 7 m of vaguely bedded, compact limestones. A variable rate of deposition caused by a fluctuating supply of terrigenous fines seems to be valid for this part of the section as well. The presence of clay-seams in horizontal partings and the presence of Chondrites point to sedimentation conditions comparable to those described for the lower part of the section. A low rate of sedimentation enabling burrowers to homogenize the sediment returns in the topmost Trubi part at Punta Piccola. Bottom conditions apparently remained favourable for bottom-dwelling life. Pyritisation in boreholes seems to be responsible for the concentric rings around the observed pipes. The upward decrease in diameter of the burrows may point to an unknown change in biotope favouring smaller sized burrowers.
The foraminiferal faunas from the Trubi, of which 73 samples have been studied, are characterized by good preservation and normal sized tests. Broken specimens are scarce, with the exception of those in sample 1400; only a small number of specimens is indeterminable. A few tests may be coated with either limonite, pyrite or carbonate thus obscuring characteristic features. Most Oolina hexagona specimens in sample 77, forming 97% of the fauna, show both carbonate and black coating. In the lower part of the Trubi (samples 1393-1405) an admixture of badly preserved benthonic specimens was observed. These forms are either etched, worn or vitreous and of light brown colour. They belong in particular to planoconvex representatives of Cibicides, especially of refulgens type, Anomalina helicina, Elphidium, Uvigerina, Bolivina and Quinqueloculina species, and sometimes Pullenia. The admixture of such badly preserved forms becomes strongly reduced or absent in the overlying part of the section. The benthonic fauna of sample 1395 is almost entirely composed of such badly preserved forms except for a few representatives of Dentalina filiformis, Globocassidulina subglobosa, Gyroidina umbonata, Oridorsalis umbonatus and o. stellatus. It is this group that is constantly well preserved in all samples from this lower part of the section. B/P ratio The number of benthonic individuals per 200 planktonic specimens varies between 0 and 22 (fig. 14). Minimum values show an irregular pattern throughout the Trubi column at Capo Rossello; they are common in the laminated sediments. Marly-clayey samples below the second, third, fourth and fifth laminated units appear to contain most benthonic forms and show a steady increase from 11 to 22 per 200 planktonic individuals (samples 80, 85, 88 and 93). Between the fifth and sixth interval and on top of this uppermost laminated bed, benthonic forms are relatively scarce again and the actual numbers show minor fluctuations only. No relation is observed with the different types of sediment in the hard-soft sequences (samples 65-70). The four samples from the middle part of the Trubi in section 4 contain benthonic faunas in quantities comparable with those of the lower part of the Trubi (figs. 14 and 15). The number of benthonic specimens has
Page 1 and 2: UTRECHT MICROPALEONTOLOGICAL BUllET
Page 3 and 4: QUANTITATIVE FORAMINIFERAL ANALYSIS
Page 5 and 6: The foraminifera. . . . . . . . . .
Page 7 and 8: Benthonic and planktonic foraminife
Page 9 and 10: and considerable lowering of the er
Page 11 and 12: topmost Messinian evaporites, chara
Page 13 and 14: literature together with Pachysphae
Page 16 and 17: Data and conclusions from the earli
Page 18 and 19: 2 3 Ammonia beccarii Bolivina dente
Page 20 and 21: LITHOLOGY The new exposure to be de
Page 22 and 23: may interfinger. Evidently biogenic
Page 24: CONCLUSIONS The mediocre preservati
Page 27 and 28: 107 107G B.C 107A 106 1394 64 1393
Page 29 and 30: Fig. 9 Laterally displaced loadcast
Page 31 and 32: Orbulina, which in turn seem to dep
Page 33 and 34: 0 10 20cm. L--L--J ~II\\ :::0 if.-
Page 35 and 36: whether its assumed intermediate st
Page 37: cate that larger burrowing organism
Page 41 and 42: 42 43 44 45 sa~ 3 4 4 Astrononion i
Page 43 and 44: the accumulation of silica-rich sed
Page 45 and 46: 1 1 i z 1 1 11 3 1 i ~ . 2 •• 7
Page 47 and 48: ently favoured clayey substrates bu
Page 49 and 50: The next higher part of the section
Page 51 and 52: Cibicides pseudoungerianus appears
Page 53 and 54: In the next higher interval the alt
Page 55 and 56: high. It remains equally possible t
Page 57 and 58: I 106 55 52 j 8 Ij I " ~ ~ ! I ll11
Page 59 and 60: 107A 107B 107C 107D 107E 107F 107G
Page 61 and 62: of the faunas remains practically t
Page 63 and 64: 5 -- 4 3 2 7 - - - - - - - - - - -
Page 65 and 66: ;.Monica Say(32) Todos Santos 8ay (
Page 67 and 68: 1000 m, the latter corresponding to
Page 69 and 70: In this respect it is interesting t
Page 71 and 72: for this interval at the three loca
Page 73 and 74: near-absence and bloom. The level o
Page 75 and 76: Fig. 30 Punta Piccola section, show
Page 77 and 78: Chlorite/montmorillonite and albite
Page 79: most of them are of the order of 15
Page 83 and 84: The change in colour from cream to
Page 85 and 86: The foraminiferal faunas from the M
Page 87 and 88: , " ~ " , , . ~ . ~
Page 89 and 90:
posite- reactions with higher a-val
Page 91 and 92:
------ Cibicides lobatu(us -- Hanza
Page 93 and 94:
Bulimina inflata, Hopkinsina bononi
Page 95 and 96:
Parker, 1954). In the Andaman Sea t
Page 97 and 98:
athymetric distribution is shown in
Page 99 and 100:
in the manganese-rich interbeds (B
Page 101 and 102:
50 1~N 47 46 45 43 4 M 42 L 41 4 39
Page 103 and 104:
Emiliani (1974) analyzed core mater
Page 105 and 106:
20323, was deposited at the transit
Page 107 and 108:
it is realized that the latter two
Page 109 and 110:
FREQUENCY D ISTR I BUTION OF SOME S
Page 111 and 112:
BENTHONIC FORAMINIFERAL ASSOCIATION
Page 113 and 114:
IK < .o~
Page 115 and 116:
ed by the increase of epiphytes and
Page 117 and 118:
G. puncticulata, recorded from Aren
Page 119 and 120:
our sample 93 suddenly shows a B/P
Page 121 and 122:
loss may be due to the folding. The
Page 123 and 124:
shallowing tendency. This quiet sed
Page 125 and 126:
One of the major aims of this inves
Page 127 and 128:
anean evidently had a nutrient supp
Page 129 and 130:
A taxonomical treatment of all figu
Page 131 and 132:
Remarks: Globigerina pseudobesa (Sa
Page 133 and 134:
Remarks: Colalongo and Sartoni (196
Page 135 and 136:
30. Earland, A. (1934). Foraminifer
Page 137 and 138:
Anderson, G. ]. (1963). Distributio
Page 139 and 140:
Hsii, K. J., Cita, M. B. and Ryan,
Page 141 and 142:
Wright, R. (1977). Neogene paleobat
Page 144:
Figs. 1a-b Figs. 2a-b Figs.3a-b Fig
Page 148:
Figs. 1a-c Figs. 2a-c Figs. 3a-c Fi
Page 152:
Fig. 1 Fig. 2 Figs.3a-b Fig. 4 Fig.
Page 156:
Morphological gradation from Globor
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UTRECHT MICROPALEONTOLOGICAL BUllETINS

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