312 ^^^6 Philippine Journal of Science imb 



conform to the wrinkling in the beds without any evidence of 

 having been shattered; hence they must have been introduced 

 after the crumpling had been accomplished. Lenses of pyrite are 

 found in the upper part of the green schists much like the 

 lenses of the same mineral in the sandy limestone or calcareous 

 sandstone member of the sedimentary series. 



BASAL IGNEOUS COMPLEX 



Altered black rocks which appear to be of the subsiliceous 

 igneous type, probably peridotites, are exposed on the southern 

 coast of the peninsula at the base of the sedimentaries. They 

 are closely jointed in several directions and are thoroughly in- 

 durated. Hand specimens reveal little except the presence of 

 serpentine. A mantle of closely derived fragmental rock, which 

 is also metamorphosed, obscures the true character and relations 

 of these basal rocks. In the outlying islands north of Caramoan, 

 also, the basal rocks are exposed, and there gneissic diorite is 

 prominent in the igneous complex. 



There is a limited area of fresh diorite on the south coast near 

 the point between Guijalo and Parubcan. Likewise there is 

 diorite in the vicinity of Mapid and around Tambang Bay on 

 the north coast. These rocks are holocrystalline, of medium 

 grain, and consist essentially of hornblende and calcic feldspars. 

 At both places the exposures form part of the basal complex into 

 which the diorite is probably intrusive. In the outcrop at Mapid 

 there are a number of veinlets containing chalcopyrite and pyrite, 

 together with quartz and some calcite. 



Along the eastern coast of the region northwest of Tambang 

 Bay there is a continuous exposure of a black, igneous-appearing 

 rock which, from its general appearance, I believe to be peri- 

 dotic in character. Both my trips along this coast were made 

 in rough weather in a small boat ; consequently I had little chance 

 to examine the outcrops. Specimens which I secured were lost 

 subsequently when my boat capsized. If the rock is peridotite, 

 it is undoubtedly to be correlated with the peridotite farther 

 west in the Paracale mining district, and the Paracale peri- 

 dotite is probably the equivalent of the metamorphosed peridotic 

 rocks in the basal complex upon which the Caramoan sedimen- 

 taries were deposited. Upon this basis the region northwest of 

 Tambang Bay is mappea as part of the basal igneous complex. 

 It may be, however, that the rock in question is a massive flow 

 related to the tuff -agglomerate-flow series. Certainly it has less 

 appearance of metamorphism than the average basal-complex 

 outcrop. 



