Pyrite framboids interpreted as microbial colonies within the Permian Zoophycos spreiten from southeastern Australia

Two types of pyrite framboids (PF, probably sulphate-reducing bacteria) have been found<br />within the <i>Zoophycos</i> spreiten, hosted in the Guadalupian (Middle Permian) glaciomarine greywacke<br />of the Westley Park Sandstone Member within the Broughton Formation from the southern Sydney<br />Basin of southeastern Australia. They are composed of non-sheathed (PF1) and sheathed (PF2)<br />sub-micron balls, respectively. Chemically, the sub-micron balls consist of iron, sulphur, carbon and<br />oxygen. Both PF1 and PF2 occur in rhythmic alternationwithin the thick, light-grey and thin, dark-grey<br />minor lamellae of <i>Zoophycos</i> spreiten. The framboids from the minor lamellae are highly abundant and<br />occur in an orderly arrangement of equal density and in a good state of preservation.Within <i>Zoophycos</i><br />spreiten no homogeneous filling, fecal pellets, or any sign of re-exploitation of the minor lamellae have<br />been recognized. No similar framboids have been observed outside <i>Zoophycos</i> spreiten. Therefore, the<br />framboids are interpreted as the pyritized remains of microbial colonies within <i>Zoophycos</i> spreiten.<br />The trace <i>Zoophycos</i> would be a multifunctional garden thatmay have been carefully constructed by the<br /><i>Zoophycos</i> maker, where different microbial colonies were orderly and carefully planted and cultured<br />within different minor lamellae. Further, it is proposed that the <i>Zoophycos </i>maker had a symbiotic<br />relationship with microbial colonies on the mutual basis of food supply and redox conditions. The fact<br />that the overlying spreiten cut the underlying ones indicates that the <i>Zoophycos</i> from the study area is<br />of an upward construction. The rhythmic alternation of both the thick, light-grey and thin, dark-grey<br />minor lamellae within <i>Zoophycos </i>spreiten may be suggestive of a gardening manner of the <i>Zoophycos</i><br />maker responding to the warm and cold changes, food supply in pulses and variations of sedimentation<br />rate for planting and culturing microbial colonies under the conditions of a glaciomarine environment<br />at the high latitudes.<br />