الملخص الإنجليزي
The Precambrian-Cambrian Boundary (PCB) was
recently interpreted within the Ara Group of the
Huqf Supergroup of Oman (Figures 1 and 2), and
dated at 542.0 million years before present (Ma)
± 0.3 million years (my) (Amthor et al., 2003;
Geology, May 2003, p. 431–434). The Ara Group is
believed to be coeval with the Hormuz Series salt
of the Arabian Peninsula and southwest Iran
(Figure 1). In just over two decades, the estimated
age of the global PCB has changed by almost 50
million years: 590 Ma (Harland et al., 1982), 570
Ma (Harland et al., 1991), and 545 Ma (Gradstein
and Ogg, 1996). This new PCB age estimate from
Oman is close to other estimates in Siberia (older
than 543.8 + 5.1 to -1.3 Ma) and Namibia (younger
than 543.3 ± 1 Ma).
