| Popis: |
The Lesotho remnant contains the type succession for Karoo low-Ti basalts of central southern Africa. The 40Ar/39Ar dating indicates that the sequence was emplaced within a very short period at about 180 Ma and consists of a monotonous pile of compound basalt lava flows which lacks significant palaeosols and persistent sedimentary intercalations. We have used geochemistry to establish a stratigraphic subdivision of the lava pile. Thin units of basalt flows, the Moshesh's Ford, Golden Gate, Sani, Roma, Letele, and Wonderkop units, with diverse geochemical character and restricted geographical distribution, are present at the base of the succession. These are overlain by extensive units of compositionally more uniform basalt, the Mafika Lisiu, Maloti, Senqu and Mothae units, which build the bulk of the sequence.Location of this section is described in Marsh et al. (1997) AGU Geophysical Monograph, 100, 247-272. Title of data set: Springbok Flats Location of Borehole RL1 (SF samples) – S24.9367 deg; E 28.3750 deg Location of Borehole RTL1 – S 24.4400 deg; E 29.1767 deg Location of Borehole WD4 – S 24.6483 deg; E 28.7450 deg Location of Borehole LB1 – S 24.8817 deg; E 28.5833 deg Borehole TF2 – base of volcanic sequence – 768m Borehole TF1 – base of volcanic sequence – 357m All Sr-, Nd- and Pb-isotope values are MEASURED values. |
