返回Google圖書搜尋

Petrology and Structure of Three Basic Igneous Complexes, Southwestern Maine

出版	University of Illinois at Urbana-Champaign, 1961
URL	http://books.google.com.hk/books?id=UNY3UDw-vmYC&hl=&source=gbs_api

註釋Three small, internally complex basic igneous bodies ranging in lithogic composition from olivine gabbro and gabbro to monsodiorite, quartz diorite, and granodiorite are exposed In southern York County, southwestern Maine ... The three complexes were mapped ... in connection with regional studies of southern York County for the Maine Geological Survey ... Approximately 500 rock samples were collected, of which about 200 were sectioned, studied, and described. Modal analyses using a Swift automatic traversing point counter and tabulator were made on 110 representative thin sections to obtain average modal compositions of the various units of the complexes. For each section 1000 points were counted. Plagioclase compositions were determined for about 175 sections by the Rittman Zone Method using a 4-axis universal stage as outlined by Emmons ... This method was usable with the rather calcic plagioclases of the more basic members of the complexes by virtue of the strong compositional coning which is almost universally present. For each section, five to ten grains were selected in order to determine average compositions. For each grain the compositions of the core, margin, and intermediate zones (as many as 10 in some sections) were determined. A total of approximately 2900 such Individual determinations were made. The emphasis during the laboratory study of these sections was placed on plagioclase compositions to the exclusion of the mafic minerals ...