28 BASIC AND ULTRABASIC IGNEOUS ROCKS— BENSON. [M ™ 0lR \? u Txix, 



gneiss, quartzite, and dolomite, clay and calc schists, and radiolarite with green-rocks, form- 

 ing narrow more or less concordant sills, but never appearing to be extrusive. In the mass, 

 serpentine, diabase and green schist may occur, associated alternating or singly with sporadic 

 masses of highly metamorphosed gabbros, which in composition are like albitediabase. Corne- 

 lius also concludes that the intrusions took place during the overthrust-movement, fol- 

 lowing planes of marked discontinuity and even traversing the broken ends of folds, though 

 occurring sill-like in the septa of the folds. 



In the window of the Lower Engadine the green-rocks of the Rhaetic sheet are again 

 exposed and have been studied by Grubenmann and Tarnuzzer ('09). They occur among 

 clay shale, chert, calc-phyllite, and radiolarite. 7 Here are green schists with spilite, variolite, 

 diabase, gabbro, hornblendite, and serpentine. Hezner's numerous excellent analyses show 

 that, with the exception of two biotite-gabbros of monzonitic composition, the plutonic types are 

 all characteristically calcic. The diabases and variolites, on the other hand, are notably different, 

 being nearly all strongly sodic, except one example which contains orthoclase. Grubenmann 

 draws special attention to their "essexitic" character. Some features of the analyses, however, 

 strongly recall those of the decalcified diabases described by Termier ('98), so that the analogy 

 suggested with spilitic rocks may not be a valid one. The association of the gabbros and ultra- 

 basic rocks on the one hand with the diabases and variolites on the other is so intimate as to 

 suggest they belonged to a single period of igneous activity. 



In the Antirhatikon, Paulcke ('04) found that the ophiolitic rocks were closely associated 

 with the most disturbed regions, and concluded that their intrusion had taken place (probably) 

 during the Tertiary orogenic movements. From Schiller's ('06) account of the most easterly 

 ophiolitic rocks in Switzerland the reader can draw the same inference. This association of 

 intrusions of basic magma with orogenic movements in Switzerland has been further discussed 

 by Hehn ('21) and Staub ('15 and later memoirs) whose writings have not been accessible to 

 the writer. 



AUSTRIA-HUNGARY. 



Eastward from here we pass to the Austrian Tyrol, where the green-rocks are exposed around 

 the framework of the window of the Tauern. Very diverse accounts are given of this region, 

 Suess (IV, pp. 169-176) following in general Termier's views. The central gneissic mass is 

 believed to be of intrusive origin but to have been brought passively into its present position. 

 Surrounding it is a frame of Lepontine rocks, Triassic conglomerates, etc., and more or less 

 calcareous Mesozoic schists which contain greenstones (altered tuffs and diabase) and serpentine 

 peridotites (as at Windisch Matrei). Becke ('03) believes that the peridotite was injected 

 during the overthrusting movements into the calc-mica-schists and green schists, which are in 

 part of Mesozoic age, and the central granite invades the serpentine. 8 Weinschenk ('03) also 

 considers this granite to be Tertiary. Northward of these rocks is a monotonous series of 

 phyllites stretching to Salzburg, where they contain Silurian fossils. Spitz ('09) has found in 

 these a series of tuffs, flows of sodic diabase and proterobase, with sills of picrite which strongly 

 suggest an affinity between these and the spilitic suite of Flett or the essexitic group recognized 

 by Erdmannsdoerfer. 



No further basic rocks have been recorded as we pass eastward through the Carpathians 

 until we come to Dobschau, where, as pointed out already, they overlie the probable extension 

 of the German Hercynian diabase and gabbroid eruptions. (See p. 20.) 



RUMANIA. 



In the southwestern end of the Carpathians is the region of the Paring, the structure of 

 which has been investigated by Murgoci ('98, '05) and Mrazec ('03). A series of schists overlain 

 by Mesozoic rocks have been overridden by a different group of Mesozoic rocks lying on a 

 different series of schists. A mass of ultrabasic rock was injected beneath the thrust-plane, 



* Discovered since the publication of the work cited (.fide Prof. Grubenmann), whose collection the writer was permitted to see. 



8 Meyer and Weber ('10), on the other hand, consider the serpentine and green schists to represent intrusions and flows in the Mesozoic rocks. 



