[BARB 3] BARBERTON 3 - BASE - Barberton Archean Surface Environments, Moodies Group

BASE - Drilling Workshop: Archean Surface Environments, Moodies Group, Barberton Greenstone Belt (MOODIES)

ICDP-Topics:
Climate & Ecosystems
Deep Life
Element Cycles
Faults


Year of Application: 2019

Expedition ID: 99999

Current Status: revised proposal

africa
BARBERTON
coastal processes
early life ecology
greenstone belt
ICDP-2017/14
moodies
ocean and athmosphere
paleosols
south africa
Master Data

Prof. Dr. Christoph Heubeck (First-PI)

Dr. David De Vleeschouwer (Workshop Participant)
Nora Bieker (Workshop Participant)
Dr. Inga Köhler (Workshop Participant)
Prof. Dr. Heinrich Bahlburg (Workshop Participant)
Dr. Dennis Harries (Workshop Participant)
Dr. Jonathan Engelhardt (Scientific Participant)
Deon Johannes Janse van Rensburg (Scientific Participant)

Projektstart:
Projektdauer:
Geologisches Alter: Archean

Latitude: 25°43'59''S
Kontinente:

Africa

Regionen & Städte:

Longitude: 31°5'33''E
Länder:

South Africa

Themen:

(1)

conformable terrestrial-marine transitions for environmental proxies;

(2)

diagnostic lithologies (such as various paleosols, nearshore BIFs, evaporites and basaltic lavas) for their environmental significance;

(3)

the compositional, facies and morphological variability of thick and laterally extensive microbial mats

(4)

sedimentary and mineralogical responses to surface variables, such as tides, climate, potential meteorite impacts, and radiation, in particular in deep-water strata

Drilling Data

Drilling Depth:
Core Yield:
Core Length:
Amount of Drill Holes:
Amount of Drill Locations:

Core Length-Drill Depth-Ratio:
Core Yield-Core Length-Ratio:

Description

The evolutionary development of oxygenic photosynthesis is a key question in early Earth research because it was and is responsible for the profound transformation of surface environments across our planet and allowed the rise of eukaryotic and complex multicellular life. Various geochemical clues suggest that there were at least temporary variations in the overall very low level of atmospheric oxygen by ~3 Ga. This is consistent with results of recent molecular clock analyses that suggest the onset of oxygenic photosynthesis prior to that time, probably via microbial consortia which included highly productive benthic cyanobacteria that colonized early shorelines. The oldest strata suitable to test the hypothesis of – perhaps local and/or temporary – oxygenation are the ca. 3.2 billion-year-old sedimentary (and minor volcanic) units of the Moodies Group in the Barberton Greenstone Belt, South Africa. These record surface processes in very well preserved and correlatable fluvial-to-prodeltaic siliciclastic rocks; in addition, the ~3.7 km thick strata provide an extremely high resolution (mean ~1 km/Ma) over a relatively short interval of 1-14 Ma. Despite tight regional folding, the metamorphic grade is only lower greenschist facies, and there is a nearly complete absence of penetrative strain due to widespread early-diagenetic silicification. This has preserved abundant primary micro- and macrotextures. Mapping has documented paleosols, terrestrial evaporites, potentially eolian strata, shoreline systems, tidal microbial mats, deltaic complexes, and marine ferruginous sediments / BIF. They provide a worldwide unique opportunity to robustly reconstruct early bio-geo-atmo-hydrosphere processes and conditions, particularly those related to diverse and well-documented microbial life, at an unrivalled level of regional and temporal resolution and during a critical period in Earth history. In order to avoid the effects of oxidative weathering, a particular problem in fine-grained strata, and to obtain continuous sections suitable for geochemical and time-series analyses, we propose to drill five key sections. Nine inclined drillholes, each of 350-600 m length (MD), will provide maximum information across a range of terrestrial-marine facies transitions. Our proposal seeks funding for drilling and related field operations in the austral winter seasons of 2020. It documents the global significance and scientific rationale, describes the selected sections, suggests testable hypotheses, and provides the technical details related to drilling, logging, core processing, management, and environmental aspects. The “earth system” and “global environmental change” themes of this proposal provide an excellent match to the themes of the recently announced UNESCO World Heritage Site encompassing these strata.

Related Publications

Agangi, Andrea, Hofmann, Axel, Eickmann, Benjamin, Marin-Carbonne, Johanna (2019). "Mesoarchaean Gold Mineralisation in the Barberton Greenstone Belt: A Review" The Archaean Geology of the Kaapvaal Craton, Southern Africa Book chapter 7 p171-184


Heubeck, Christoph (2015). "Fig Tree Group" Encyclopedia of Astrobiology p1-2


Heubeck, Christoph (2015). "Moodies Group" Encyclopedia of Astrobiology


Heubeck, Christoph, Engelhardt, Jonathan, Byerly, Gary R., Zeh, Armin, Sell, Bryan, Luber, Tim, Lowe, Donald R. (2013). "Timing of deposition and deformation of the Moodies Group (Barberton Greenstone Belt, South Africa): Very-high-resolution of Archaean surface processes" Precambrian Research 231 p236-262


Heubeck, Christoph (2009). "An early ecosystem of Archean tidal microbial mats (Moodies Group, South Africa, ca. 3.2 Ga)" Geology 37 p931-934