Evidence for rapid environmental changes in low latitudes during the Late Silurian Lau Event: the Burgen-1 drillcore, Gotland, Sweden

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Evidence for rapid environmental changes in low latitudes during the Late Silurian Lau Event: the Burgen-1 drillcore, Gotland, Sweden. / Calner, Mikael; Eriksson, Mårten.

In: Geological Magazine, Vol. 143, No. 1, 2006, p. 15-24.

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T1 - Evidence for rapid environmental changes in low latitudes during the Late Silurian Lau Event: the Burgen-1 drillcore, Gotland, Sweden

AU - Calner, Mikael

AU - Eriksson, Mårten

PY - 2006

Y1 - 2006

N2 - Erosional outliers are an important component of the Ludlow (Late Silurian) stratigraphy of Gotland, Sweden. However, due to the poor degree of exposure, outcrop studies have not revealed a detailed section from any of these outliers. The first complete stratigraphy of such an erosional remnant. the Burgen outlier, is presented here, based on the recently recovered Burgen-1 drillcore. Stratigraphical units encountered are, from oldest to Youngest, the uppermost Hemse Group (> 35 m), Eke Formation (0.4 m), Burgsvik Formation (3.4 m) and the basal Hamra Formation (12 in preserved). Based on carbon stable isotopes and lithological correlation to nearby outcrops that are zoned by conodonts, it can be concluded that the most profound late Ludlow sedimentary changes took place shortly after the onset of the globally recognized Lau Event (delta(13)C values reach 8.7 parts per thousand in the lower Hamra Formation). Sedimentary changes include development of discontinuity surfaces, widespread occurrence of an intraclastic conglomerate, increased microbial activity (Rothpletzella and Wetheredella), and influx of clastics to the basin. These changes are linked to substantial base-level changes during the event. A general comparison with the Prague basin suggests contemporaneous sedimentary changes on Baltica and on cratonic elements from peri-Gondwana during the event.

AB - Erosional outliers are an important component of the Ludlow (Late Silurian) stratigraphy of Gotland, Sweden. However, due to the poor degree of exposure, outcrop studies have not revealed a detailed section from any of these outliers. The first complete stratigraphy of such an erosional remnant. the Burgen outlier, is presented here, based on the recently recovered Burgen-1 drillcore. Stratigraphical units encountered are, from oldest to Youngest, the uppermost Hemse Group (> 35 m), Eke Formation (0.4 m), Burgsvik Formation (3.4 m) and the basal Hamra Formation (12 in preserved). Based on carbon stable isotopes and lithological correlation to nearby outcrops that are zoned by conodonts, it can be concluded that the most profound late Ludlow sedimentary changes took place shortly after the onset of the globally recognized Lau Event (delta(13)C values reach 8.7 parts per thousand in the lower Hamra Formation). Sedimentary changes include development of discontinuity surfaces, widespread occurrence of an intraclastic conglomerate, increased microbial activity (Rothpletzella and Wetheredella), and influx of clastics to the basin. These changes are linked to substantial base-level changes during the event. A general comparison with the Prague basin suggests contemporaneous sedimentary changes on Baltica and on cratonic elements from peri-Gondwana during the event.

KW - Baltica

KW - Gotland

KW - Silurian

KW - microbial

KW - Lau Event

KW - stable isotopes

U2 - 10.1017/S001675680500169X

DO - 10.1017/S001675680500169X

M3 - Article

VL - 143

SP - 15

EP - 24

JO - Geological Magazine

T2 - Geological Magazine

JF - Geological Magazine

SN - 0016-7568

IS - 1

ER -