LaGorce Formation, metasedimentary rocks

Fig. 6.8 Rb-Sr age determinations of metasedimentary rocks of the LaGorce Formation from the valley of the Blackwall Glacier, Nilsen Plateau (Fig. 6.7). The dates and initial Sr/ Sr ratios were calculated by Eastin (1970) by the methods of York (1966, 1969) and have been adjusted to = 1.42 x 10" year" Isochron A is based on four colinear data points (472, 474, 475. and 476). Line B is defined by samples 471 and 473 which have the highest Rb/ Sr ratios and have lost some in situ produced radiogenic Sr. Plotted from data by Eastin (1970)...

The igneous rocks of the Wyatt Formation occur at many locations within the Queen Maud Mountains, as well as in the Horlick and Thiel Mountains. In spite of these extensive exposures, the origin of the Wyatt Formation is still uncertain because in some places it clearly intruded folded metasedimentary rocks of the LaGorce Formation, whereas in other places it over-lies them conformably. In addition, hydrothermal alteration of the rocks and the effects of regional metamorphism described by Minshew (1967) have disturbed the isotopic composition of strontium of the rocks, which has caused data points to scatter on Rb-Sr isochron diagrams and caused large uncertainties in age determinations of the Wyatt Formation listed in Table 6.5. 

Fig. 7.4 The geology of the Wisconsin Range and of the Long Hills is dominated by the Granite Harbor Intrusives of the Wisconsin Range Batholith. These granitic rocks intruded the metasedimentary rocks of the LaGorce Formation and the metavolcanic rocks of the Wyatt Formation, both of which also...

---