GM5.3/BG7.4/CL4.38/PS4.7

Earth - Evolution at the dry limit (co-organized)

Convener: Tibor J. Dunai
Co-conveners: Eduardo Campos , Cristina Dorador , Claudia Knief , Laura Evensta

Water is the defining feature of the habitable Earth; it is essential for all life as we know it. Evolution and maintenance of life in extremely water limited environments, which cover significant portions of the Earth, is not well understood. Akin to life, water-driven processes leave unique marks on the Earth’s surface. Mars is the only other planet currently known to bear the marks of water-driven surface processes, albeit fossil and of great age. The slow biotic and abiotic surface processes that may operate even in the virtual absence of liquid water are still essentially unknown. What is evident is that transient episodes of increased water availability can leave long lasting traces in extremely water limited environments. Intriguingly, those traces of bursts in Earth surface evolution have rarely been related to bursts in biological colonization/evolution, and vice versa, although both relate to the same trigger: water.

The objective of this session is to showcase research on the mutual evolutionary relationships between Earth surface processes and biota in arid to hyper-arid systems, where both biota and Earth surface process are severely and predominantly limited by the availability of water (rather than by extreme temperatures).

Solicited topics include (not exhaustive):

• fingerprints of biological activity at the (water) limit of the habitable Earth
• surface processes operating in the (virtual) absence of liquid water on Earth or extraterrestrial analogues (e.g. Mars)
• thresholds for biological colonization and concurrent fluvial transformation of landscapes
• tipping point(s) of biotically and abiotically controlled Earth surface systems
• chronometric and spatial information on the colonization and radiation of biota terrestrial climatic records of (hyper-) arid regions on Earth

10 Jan 2019, 13:00 CET is the deadline for receipt of abstracts

https://meetingorganizer.copernicus.org/EGU2019/session/30744

During this year’s late summer, B01 undertook the fourth field trip to the Atacama Desert, which at the same time completed the overall field campaign of phase 1. During these field trips Tim Böhnert, Agathe Kozok, Federico Luebert, Felix Merklinger, Dietmar Quandt and Alexandra Stoll finalized the sampling of eight transects along the coastal and Andean ranges of the northern Atacama Desert. These transects were located in the central and northern CRC core areas to assess floristic composition and vegetation turnovers at the dry limit. In order to understand the origin, the colonization and the diversification of the Atacama Desert flora, the genera Atriplex (Amaranthaceae), Cristaria (Malvaceae) and Cryptantha (Boraginaceae) were extensively sampled for downstream phylogenetic studies. Furthermore, to reconstruct the biogeography and to quantify gene flow and its directionality within broadly distributed species/species complexes, 2,195 individuals of four plant groups (Tillandsia landbeckii (Bromeliaceae), Huidobria fruticosa (Loasaceae), Ophryosporus spp. (Asteraceae), Eulychnia spp. (Cactaceae)), originating from 136 populations, were collected. In total, nearly 1,000 plant specimens were vouchered for identification and further floristic, phylogenetic and population genetic analyses.

A Master-Student excursion for the students from the University of Cologne was conducted during end of September till mid of October to the Atacama Desert and the high Andes. In total up to 16 students and some scientist of the CRC travelled to Chile. The excursion was subdivided into several different geological and geomorphological aspects to introduce the students the broad variety and characteristics of the Atacama Desert and Andes of northern Chile. Topics varied from Coastal Neotectonics at Mejillones Peninsula, to copper formation and mining at Baja Blancas and Chuquiqamata, followed by the tectonic evolution of the Andes and Cordillera Domeyko, Salar evolution, Andean magmatism, hydrothermal alteration and ignimbrite flare-ups, to high altitude lake and paleo-lake systems, large-scale tectonic features at the Huayalas anticline and Oxaya block rotation, to the main research area of the CRC, the hyperarid Atacama Desert. During the last days the students experienced the indescribable feeling of being in a hyperarid desert with its barren landscape. Several smaller field projects were conducted to show and teach the student our recent scientific work in the respective study areas of the CRC, how to interpret certain kind of landscapes, how to get samples and how to discuss in the field different processes and interactions of climate variability and landscape processes. Many thanks go to Gabriele Gonzalez for his lovely excursion day at Mejillones Peninsula and Eduardo Campos for his effort organizing visits in the local copper mines and many explanations and teaching about ore forming processes.

Excursion supervision: B.Ritter, Prof. T.Dunai