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intercalations and the rapidity with which lithological changes take place in them laterally. The extraordinary variation in the ages of the underlying substrata, which may vary in a few miles between widely separated Permian and Uralian calcareous horizons, the thickness of which is fairly well known, leads him to insist on the enormous erosion following the epirogenic uplift which resulted in the formation of the conglomerates.
Deprat's survey touched the eastern edge of the Red Basin of Central Yunnan and its rocks are mapped, like the sandstones of the group just described, as “ Série gypso-salifère, grèso-marneux”. Between Yunnan Fu and Tungch'uan Fu (26' 24' : 103° 12'), where the basic lavas attain their greatest development, the Red Beds appear to be absent.
South of the latitude of Luliang, according to Deprat, above the Upper Permian Red Beds and the basic rocks, there follows a series of coarse sandstones and psammites which frequently contain coal seams. They are particularly well exposed in the Milê region and towards the north-east, where they exhibit an interrupted series of coal exposures over a distance of 80 kilometres (50 miles). At least 300 metres (984 feet) thick near Milê, they consist of dark, reddish-brown, well-bedded, somewhat incoherent, micaceous sandstones, passing into a complex of variegated marls, pulverulent marly shales and soft sandstones which in their turn grade insensibly into fossiliferous rocks of the Middle Trias. Both these divisions, here and elsewhere, lying either on the Lower Permian limestones or on the basalts, are placed in the Werfenian by Deprat. This is doubtless correct in the case of the uppermost of the two, as it contains typical forms of the Lower Trias of Europe amongst its lamellibranch remains. The flora of the coal seams of the lower division, however, contains Gigantopteris nicotianæfolia Schenk and although Zeiller believed the flora to be of Lower Triassic age, this particular plant, as I shall show later, is now generally accepted as an indication of the Middle Permian. The position assigned to the psammitic series by Deprat must therefore be revised. 1
In my first account of the Red Beds as they occur in the Yunnan Fu area, published in 1914,2 I described how their basal conglomerates
reston eroded foraminiferal limestones, which Personal Opinions.
I believed to be of Uralian age. In the high cliffs of the western shore of the Yunnan Fu lake, Deprat had at that time mapped limestones which he considered to belong to the Lower and Middle Permian and I came to the conclusion therefore, that the Red Beds of the same neighbourhood could not be older than Upper Permian. Later, more extended studies . led me to believe that the Red Beds must extend into the Trias, a view expressed cautiously in 1916 and definitely adopted in 1923.1 2
1 Mem. Serv. géol. Indochine, Vol. 1, Fasc. 1, pp. 153-174, (1912). • Rec, Geol. Surv, Ind., Vol. XLIV, Pt. II, p. 114, (1914).
The publication of Dr. F. R. Cowper Reed's results of his examination of my fossil collections from Yunnan, in 1927, though it
could supply no direct evidence on the age F; R. Cowper Reed, of an unfossiliferous formation, at the same 1927.
time brought forward no new facts to lead to a revision of the limits I had already allotted to the Red Beds.3 The underlying limestones were classified into Lower Carboniferous, Upper Carboniferous and Permo-Carboniferous, and, amongst the foraminifera, the only species specifically determined was Neoschwagerina craticulifera (Schwager), from Tzumenlu in the vicinity of Yunnan Fu. Once classified as an Upper Uralian form and indeed placed by Cowper Reed in the Upper Carboniferous, this species is now generally regarded as belonging to the Lower Permian.4
At Talishao (25° 14' : 99° 20'), some 20 miles to the west of the western edge of the Red Basin of Yunlung, from which it is separated by a band of pre-palæozoic rocks and brecciated limestone of supposed Devonian age, I made a large collection of fossils, regarding which Dr. Cowper Reed has remarked :-“ The relations of this fauna point clearly to some part of the Permian described by previous authors in Eastern Asia. Many of the species are identical with or closely allied to those occurring in the Middle and Upper Productus Limestones”.5 Loczy had already described a few fossils from the same locality as Permo-Carboniferous, but Frech correlated the beds with the Arta Stage of the Urals which he regarded as the equivalent of the Lower Productus Limestone of the Salt Range.
Grabau has enumerated Cowper Reed's provisional list of these fossils which was published in 1924,” and remarks as follows:
1 Rec. Geol. Surv. Ind., Vol. XLVII, Pt. IV, p. 2:29, (1916).
Reed, following Tschernyschew, refers this fauna to the PermoCarboniferous, considering it essentially equivalent to the Middle Productus Limestone. According to the classification here adopted, this is regarded as Middle Permian and this is in accordance with the faunas of China and Mongolia. The succeeding Permiar horizons are represented by continental Red Beds". 1 Whatever the exact position of the Talishao beds may be in the Chinese Permian, the Red Beds must be much younger on account of the pronounced unconformity at their base.
The bearing of Dr. Cowper Reed's investigations of my Mesozoic collections from Yunnan and of the more recent determinations of Sir A. Seward and Prof. B. Sahni of the plant remains, on the upper limit of the Red Beds, is deferred to a later paragraph.
B. Opinions of Later Observers. My views on the age of the Red Beds were confirmed by Prof. J. W. Gregory, at any rate as far as the Yunlung Basin is concerned,
in his account of the Percy Sladen Expedition J. W. and C. J. Gre
to Chinese Tibet in 1922.2 Under the heading
“ Permo-Triassic Systems”, he states the Carboniferous was succeeded in North-Western Yunnan by a widespread series of red rocks which are economically important for their salt beds and which occupy three basins. The first and largest, extending over about 1,500 square miles, reaches from near Lanping (26° 27' : 99° 30' approx.) on the north-west, past Shihmenching and Yunlung, across the Yungchang-Tali Fu road in the south, and from near the Yungping river on the west (25° 27' : 99° 31') to Yangpi (25° 40' : 99° 59') on the east. A second basin lies farther east near Yunnan Fu, whilst the third occurs at Yakolo on the Mekong, (29° 4' : 98° 33') south-west of Batang in Szechuanese Tibet. Prof. Gregory did not travel further east than Tali Fu and he was thus unaware of the far greater extent of the Red Beds in Central Yunnan than in the Yunlung Basin, which I have already suggested may only be a projecting portion of the former.
Gregory described the rocks as chiefly red shales and sandstones, some of aqueous and some of subaerial origin. He found no traces of marine beds in the series, but considered that the proximity of the sea during the deposition of part of them was indicated by the thick beds of rock salt and gypsum. The rocks, as a whole, recalled to his mind those of the British Trias, one of the most widely used freestones in particular, which is cut into slabs and arches for graves, being indistinguishable from the St. Bees Sandstone of the English Bunter. Some of thy red marls are also similar to those of the Keuper.
Stratigraphy of China ", Vol. 1, p. 490, (1923). 2 Phil. Trans., Ser. B, Vol. 213, p. 224, (1925).
“The age of this series is fixed”, he states, “in the absence of fossils, by its stratigraphical relations. It rests against the Carboniferous along its northern margin between Lanping and Yangtsen, and clearly overlies the fossiliferous Carboniferous limestone near Shuichai, and, according to Desgodins and von Loczy, also near Yakalo.1 Mr. Coggin Brown refers these beds to the Upper Permian and Lower Trias, and that age seems most probable. Their deposition earlier than the marine Trias of north-western Yunnan agrees with their physical history ; for the marine limestones of Likiang (26° 58' : 100° 13') and the Janu La* (about 28° 20' : 99° 2') and the salt-bearing red beds of Yakalo and the Yunlung basin indicate such different geographical conditions that these two series of rocks were probably formed at different times”.
The marine Trias referred to above was determined by Prof. Gregory himself and by Dr. Cowper Reed to belong to the upper part of the system, but in the absence of contacts of the two groups, the upper limits of the Red Beds in the Yunlung Basin remain conjectural.
The coarse conglomerate followed by red and green sandstones and grits and by chocolate coloured shales which cover the crystalline rocks of the T'sang Shan to the east of the basin, near Yangpi, which Gregory regarded as forming part of his Minchia Series of Devonian age, probably belong, in my opinion, to the Red Beds, but, in any case, as he was well aware, a little further to the south, the Permo-Trias must rest directly on the pre-Palæozoic floor. . Similar conditions apply in the Mekong valley at its western limits, but here the basal conglomerates have not been found and the contact may be abnormal.
1" Die Wissenschaftlichen Ergebnisse der Reise des Grafen Bela Szechenyi in Ostasien ”, Vol. 1, p. 723, (1893).
2 Mem. Geol. Surv. Ind., Vol. XLVII, p. 58, (1923).
* The Janu La (15,800) is the pass, south-east of Atuntzu, over the Mekong Yangtzo dividing range.
On Sheet No. 14 of the Geological Atlas of Eastern Asia, on the scale of 1: 2,000,000, published by the Geographical Society of
Tokyo in 1929, the Red Beds of the centre, Japanese Geological Map of Yunnan.
west and south of the Province are grouped
together as Permo-Triassic shales and sandstones, stretching from the Yangtze valley, north-north-east of Tali Fu, far to the south. The Red Beds of Eastern Yunnan are classified as Permo-Carboniferous shales and sandstones. Those of the Red Basin of Szechuan, the southern portion of which enters this sheet, are shown as shales and sandstones of Upper and Lower Cretaceous ages, respectively. No connection is indicated as existing between the two basins which are separated by older rocks to the north and north-east of Yunnan Fu.
The Permo-Triassic age of the Yunnanese Red Beds was challenged by Arnold Heim and K. Krejci-Graf in 1930. They travelled Views of Arnold Heim from Yunnan Fu through Fumin Hsien and
K. Krejci-Graf. thence across the Yangtze into Szechuan by (1930).
the Huili Chou route, remarking that with the exception of the valley of this river, they traversed Red Beds continuously for ten days. The Red Beds are stated to be unfossiliferous and as thick and typical as those of the Red Basin of Szechuan between Chungking and Chengtu. An older, folded, basal series containing some green sandstones, is followed by blood red shales, marls and sandstones, from 2,000 to 3,000 metres (6,560—9,840 feet) thick, and over these again lay brick red sandstones at least 500 metres (1,640 feet) in thickness, forming the cores of the troughs. These three groups are compared with the three subdivisions of the younger Red Beds of Szechuan as described by Heim, the oldest of which, the Tseliutsin (Tzuliutsing), or Ts’ienfuyen formation, as it is now officially termed by the Geological Survey of China, carries a fresh water, molluscan fauna of Wealden type, and on grounds of lithological analogy the Red Beds of Yunnan were also regarded by Heim and Krejci-Graf as Cretaceous. It is added that in the same way as von Richthofen spoke of the Red Basin of Szechuan ", so it is possible to speak of a “Red Basin of Yunnan ".1
Prof. Arnold Heim however has abandoned his opinion on the
1 Zeit. Ges. für Erdkunde zu Berlin, pp. 266-69, (1930).