berg2_besser

Summer School 2011

Marine anoxia and submarine exhalative mineralisation

Precambrian-Cambrian transitional strata, not only in southern China,
include abundant anoxic fine-grained sediments, widespread marine
exhalative mineralization, and a number of early diagenetic alteration
products, including phosphatized and silicified units. Similar
lithologies, well-exposed in central Germany, were therefore of
considerable interest to the Forschergruppe members and their Chinese
counterparts. We therefore designed a summer school studying these
occurrences in the field, in our laboratories and in the numerous
exhibitions and museums of north-central Germany which display fossil
and ore samples of these strata, hoping that we may infer events and
processes that might have occurred in an analogous manner in southern
China, and possibly globally, near the Precambrian - Cambrian boundary.

After the arrival of our Chinese guests in Berlin and an introductory
seminar, a total of 28 German and Chinese scientists and
Ph.D.-students set off by bus to the Harz Mountains of central
Germany. This Paleozoic basement terrane  was block-faulted and
uplifted by several km due to transpressional tectonics in the
Cretaceous, thereby tilting and upwarping Permian to Cretaceous
sedimentary strata along its margins and exposing a slightly
metamophosed and significantly deformed convergent-margin
lithologic-tectonic assemblage in its interior.  During the 10-day
field excursion, we visited a Devonian reef complex (Iberg), a large
underground mine exploiting sedimentary-exhalative Pb-Ag-Zn
mineralization (Rammelsberg) and several roadside outcrops of
finger-thin polymetallically mineralized beds in anoxic shales of the
Early Permian (the so-called "Kupferschiefer"). In particular the
latter occurrence may be analogous to the base-Cambrian polymetallic
strata which are mined throughout southern China, having been
precipitated from the sea water through submarine exhalative
activities and then concentrated through early diagenetic processes,
and attracted much interest from German and Chinese participants
alike. Also, the Rammelsberg Mine outside the city of Goslar, which
had provided much wealth to finance the endeavours of German medieval
rulers through its >1000 year-long operation, impressed all of us
through its ancient mining machinery and the colorful mineral
specimens. It is now a UNESCO World Heritage site.

Central Germany is not only an ancient cultural region but has also a
well-develoiped dense infrastructure  which allowed ready access to
the geological sites of interest. Because the region is also of
considerable scenic beauty, touristic attractions abound. The field
trip leaders had wisely incorporated several of them into the tour
program.

After our return to Berlin, the summer school continued in small-group
study. Paleontologists, geologists and geochemists congregated to
discuss their findings in China, compare them to the situations they
had encountered in the central German mountains, and to discuss
research activities and future field work.

The summer school was, as their predecessors in 2009 and 2010, a
success and provided compact continuing education for young and
established scientists from both countries. The organizers are
grateful to DFG and the Center for International Cooperation without
whose financial support this trip would not have been possible.