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The Devonian of Western Karakorum (Pakistan)

Gaetani M., Mawson R., Sciunnach D., Talent J.

Acta Geologica Polonica

2008

Vol. 58, no. 3

261-285

Devonian rocks crop out in several thrust sheets in the sedimentary belt of North-Western Karakorum, both to the south and to the north of the Reshun Fault. Gently metamorphosed Devonian dolostones and volcanics are also present in the Tash Kupruk Zone north of the thrust sheet system. The most complete succession is found in the Karambar Thrust sheet where dolostones and recrystallized limestones (Vandanil Formation) lie above the black shales and siltstones of the Baroghil Group. The age of the Vandanil Formation is poorly defined, approximating latest Silurian or earliest Devonian at its base and proven to be Pragian in the 4th of its 5 lithozones. The overlying Chilmarabad Formation is divided into two members. The lower member is a mixed siliciclastic-carbonate package, present in most southern and western thrust sheets. The upper member is ubiquitous; it consists of dolostones, often stromatolitic. The calcareous part of the Tash Kupruk Zone consists of similar facies. The carbonate flats of the Chilmarabad Formation display a trend towards emersion towards the top, and are overlain, with regional unconformity, by the basal unit of the Shogram Formation. The base of the latter consists of arenite and fine conglomerate (deposited in an alluvial setting) overlain by alternating marine bioclastic limestones and litharenites with one or two coral bafflestones in the middle to upper part. The age of the lowermost part of the Shogram Formation is Givetian, extending through the Frasnian and seemingly into the Famennian, but the last is poorly documented (contrasting with the classic Shogram and Kuragh sections of Chitral); it reflects a return to fine terrigenous input. The inferred palaeogeography accords with the Northern Karakorum having been part of the Gondwana margin during the Devonian. Awide, mostly calcareous platform, characterised extensive areas of the Karakorum, Central Pamir, Badakhshan and, in a minor way, Central Afghanistan (Helmand Block). The sandstone petrography suggests that clastics polluting the carbonates originated from erosion of a pre-existing sedimentary cover. During the Givetian a first rifting episode, possibly echoing the opening of an ocean to the east, affected the whole area,with volcanic outpourings in the rifts, while eroding shoulders fed the basins, though never extending as deep as the crystalline basement. A minor volcanic input is also recorded. The tectonic pulse almost ceased during the Frasnian, gradually resuming towards the end of the Devonian.

Wybrane pierwiastki towarzyszące w piaskowcach białego spągowca w złożach rud miedzi Kopalni Rudna

Kaczmarek W., Rożek R., Śliwiński W.

Górnictwo Odkrywkowe

2005

Vol. 47, nr 2

29-33

Artykuł prezentuje dane na temat zawartości i rozmieszczenia poziomego metali towarzyszących (Ag, Co, V, Ni, Mo) w piaskowcowej rudzie miedzi na obszarze kopalni Rudna. Zawartość wymienionych metali jest w rudzie piaskowcowej niższa niż w rudzie łupkowej i dolomitowej (wyjątek stanowi kobalt). Zawartość miedzi spada w rudzie piaskowcowej w kierunku NE, podobnie zachowują się Mo, V, Ni. Wszystkie te metale wykazują ponadto zmniejszone koncentracje w obrębie elewacji i liczne drobne maksima w obrębie depresji. Przy czym maksima te dla poszczególnych pierwiastków nie pokrywają się ze sobą, a maksima molibdenu wykazują ponadto przesuniecie w kierunku brzegów depresji. Srebro i kobalt wykazują tendencje przeciwstawną, ich zawartość rośnie ku SW. W przypadku srebra obserwuje się wyższe koncentracje tego pierwiastka na terenie depresji, podczas gdy kobalt wykazuje jako jedyny z analizowanych pierwiastków związek maksimów z elewacjami.

The article presents some data concerning the content and distribution of subsidiary metals (Ag, Co, V, Ni, Mo) in the sand-stone ore within the Rudna Mine. The content of those metals in the sandstone ore is poorer than in shale and dolomite ores (the exception is cobalt). The copper content in the sandstone ore decreases in NE, and so Mo, V, Ni does as well. Ali those metals concentrations are poorer within the elevation (paleohigh) areas and numerous small maximum concentrations occur within depressions. The richest concentrations of particular metals don't coincide with each other and the maximum Mo content is moved close to the elevation borders. The distribution of silver and cobalt presents the opposite trend, the content increases towards SW. The richest concentrations of silver are noticed within depression areas, whereas the high cobalt content, as the only one of analysed metals, is involved with elevation areas.