Pegmatite, Mt. Madison

The Shackleton Limestone of the Churchill Mountains south of the Byrd Glacier is tightly folded and was intruded by ... small plutons of hornblende granite, pyroxene-hornblende diorite or gabbro, and dikes of quartz porphyry, all probably related to the Hope Granite (Grindley and Laird 1969). Faure and Felder (1984) described and sampled a complex pegmatite that intruded the Shackleton Limestone on one of two 

Dick Conglomerate S Starshot/Goldie (outboard Douglas Conglomerate Holyoake 

McCreath and Sons, Inc., Harrisburg, PA, chemical analysts Sample Bi-1 was analyzed by semi-quantitative optical spectro-graphy. In addition to the metals listed in the table, sample Bi-I contained detectable concentrations of Mn, B, Sn, Ag, and Mg 

The Sr concentration of the Shackleton Limestone adjacent to the pegmatite is 179.3 ppm and its Sr/ Sr ratio is 0.70996 0.00031. The comparatively high value of the Sr/ Sr ratio of the Shackleton Limestone is consistent with the increase in this ratio in the oceans during the Cambrian Period which peaked during the late Middle Cambrain at about 0.7093 (Faure and Mensing 2005). 

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