Oil & Gas Journal - September 7, 2015

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.