FIG. 3 SEISMIC LINE MD40-05: PROJECTED SAMPLES
SN
Crystalline basement Basalt above basement
MD84582
Pliocene
MD84583
Early Miocene SU7726
Mio-Pliocene
84DR04
Upper Eocene
SU7705
Cretaceous
SU7727
Eocene
MD84581
Pleistocene
above basalts
84DR03
Miocene above
basaltic breccia
84DR02
Miocene with
basaltic breccia
SU7702
Pleistocene
above basalts
southern portions of Paisley Mount, along with tuffs similar
to those from the top of Mount Paisley (Fig. 1). The matrices
of the tuffs are green, rarely reddish, without calcite or dolomite, and contain fine basalt fragments.
Coring of sands and arkosic fragments took place up-dip northwards at the base of Pleistocene oozes (MD84582,
2,025 mbsl). The same location (MD84583, 1,905 mbsl)
also features Early Miocene (NN2) oozes with reworked Upper Eocene (NP20) while further to the north Eocene and
Miocene-Pliocene sediments cover the sea bottom (SU7726,
2,230 mbsl). At the southernmost part, cores showed calcareous sands of probable Cretaceous age (SU7704, 1,912
mbsl).
Fig. 3 shows a projection of the dredged and cored material on seismic line MD84-05. A tentative interpretation
points to the strong reflector and unconformities east and
west of the volcanic mount.
The eroded crystalline basement emerges south of Mount
Paisley at the base of the western flank of the ridge (84DR05,
2,450-1,950 mbsl) and consists of recrystalized pelites and
arkoses with small clasts of gneisses (Fig. 4). A comparable
sequence was found further south at 16°S (84DR09). San-dy-clayey carbonates of Late Cretaceous age (SU7704, 1,807
mbsl) and Late Miocene (NN11) oozes (U77-0003, 1,815
mbsl) were sampled above the pelites and arkoses. On the
same flank, Coniacian oozes (SU7720, 1,845 mbsl) are as-
Rock samples
The northern part of the ridge, Paisley Mount around 14°S,
offers a WNW-ESE cross section (Fig. 1). At the western
flank, fragments of altered aphyric basalt were cored below Pleistocene oozes (MD84581, 2,063 m below sea level [mbsl]). Upslope, decimetric angular blocks of vesicular greenish and reddish basalts and tuffs were recovered
(84DR03, 1,831-1,760 mbsl). The basalts are alkaline with
plagioclase, K-feldspar, biotite, kaersutite, apatite, and relics
of clinopyroxene.
Dredging of basaltic breccia, conglomerates, and Miocene
bioclastic limestone (84DR02, 810-800 mbsl) occurred further east. The breccia elements are vesicular alkaline basalts
with clinopyroxene phenocrysts set in a groundmass rich in
plagioclase, K-feldspar, clinopyroxene, and phillipsite crystallizing in the vesicles. The basaltic elements are reworked
and cemented with a bioclastic carbonate matrix rich in
planctonic foraminifers of Miocene age. The coring also consists of basaltic glass fragments at the eastern flank of the
mounts (SU7702, 1, 110 mbsl).
The seismic line is parallel to the cross section and situated around 10 km to the north (Fig. 2). Fig. 3 shows a projection of the dredged and cored material on seismic line
MD84-23 and interpretation of the strong reflectors and unconformities east and west of the volcanic mount.
Research expeditions have dredged pelagic sediments
with polymetallic crusts (84DR04, 2,255-1,905 mbsl) at the