92 RESEARCH IN CHINA. 



Ts'in-ling-shan, and appear to be part of the zone under consideration. 

 The western continuation of the mountain system, the Nan-shan ranges, 

 was a scene of igneous intrusions, as described by Obrutchov, but whether 

 of pre-Cambrian, middle Paleozoic, or Mesozoic date we can not distin- 

 guish. In western Ssi'-ch'uan, longitude 99 to 103 east, latitude 30 north, 

 between Ba-tang and Ja-chou (Ya-chou), where Paleozoic and Mesozoic 

 strata are folded around the eastern margin of the Tibetan plateau, Loczy 

 observed great bodies of granite in the metamorphic schists. He com- 

 pares the rocks with the Nan-shan sandstone, and again we are uncertain 

 whether the intrusions are pre-Cambrian or Mesozoic. In this connection 

 it is worth while to point out that the Ts'in-ling-shan and the Alps of west- 

 ern Tibet bound the depressed basin of Ssi'-ch'uan on the north and west 

 and coalesce at its northwestern corner. The geologic conditions which led 

 up to the Permo-Mesozoic diastrophism were identical in the two belts, so 

 far as the stratigraphic history is concerned; the effects of folding appear 

 to have been much the same; and it is probable that the phenomena of 

 intrusion which affected the one occurred in the other. The southern con- 

 tinuation of the mountains of Ssi'-ch'uan and Yiin-nan extends through 

 Indo-China, where Fuchs and Saladin distinguish an ancient granite and a 

 microgranulite of Carboniferous or post-Carboniferous age.* In view of 

 the reconnaissance nature of the observations the age of the ancient granite 

 may be considered undetermined and possibly Mesozoic. 



In this connection it is desirable to mention the fact brought out by 

 Haydenf in course of the Younghusband expedition to Tibet that Jurassic 

 and Cretaceous strata of southeastern Tibet, south of Lhasa, are highly 

 metamorphosed and intruded by granite. At first thought the suggestion 

 occurs that the post-Cretaceous age of these intrusions may indicate a like 

 recency for the intrusions of the Ts'in-ling-shan; but the unaltered char- 

 acter of the supposed Jurassic in that region appears to preclude the idea; 

 and it is more likely that the events in the Ts'in-ling-shan and in south- 

 eastern Tibet are successive than that they were contemporaneous. 



In strong contrast to the pronounced folding, metamorphism, and 

 intrusion that characterize the central Ts'in-ling-shan and the Han valley 

 is the moderate deformation of the region on the south. Folded Paleozoic 

 strata, which are indeed closely folded and even overthrust, but not altered, 

 adjoin the metamorphic district along a remarkably sharp boundary, and 

 pass into the wide flexures of the middle Yang-tzi' or the synclinorium of 

 the Red Basin. On the Yang-tzi' there is complete conformity of dip up to 

 and including the K'ui-ch6u beds (Rhaetic). About the Red Basin there 



*Annales des Mines, 1882, 8me serie, Memoires 2, pp. 224-225. 

 f Report Geol. Sur. of India, 1905. 



