An abyssal carbonate compensation depth overshoot in the aftermath of the Palaeocene–Eocene Thermal Maximum
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چکیده
1 The PETM represents one of the largest and most abrupt greenhouse warming events in Earth’s history. Marine and terrestrial records document a global >2.5‰ negative carbon isotope excursion (CIE; refs 1–3) coincident with global mean surface ocean warming of >4 °C (ref. 4) and geochemical and sedimentological evidence for ocean acidification5,6. Collectively, these lines of evidence suggest a rapid (103–104 years) and massive (~3,000–10,000 PgC) release of 13C-depleted carbon into the ocean–atmosphere system7–9. The PETM thus offers the opportunity to examine the response and recovery of the global carbon cycle and seawater carbonate chemistry to an ancient CO2 release similar in magnitude to ongoing anthro pogenic fossil fuel combustion10. Current understanding of long-term carbon cycle processes predicts that a rapid carbon injection should cause a short-term (0 to tens of thousands of years (kyr)) period of ocean acidification featuring reduced seawater carbonate saturation (Ω), followed by a longer-term (10–100 kyr) period of carbonate oversaturation due to elevated rates of terrestrial silicate weathering (see Box 1). This carbonate saturation overshoot manifests itself in several carbon cycle model simulations of the PETM9,11 as an over-deepening of the CCD relative to its pre-event depth. Yet no records exist from abyssal sites below the pre-PETM CCD with which to detect possible CCD over-deepening. Sedimentary records from above the CCD (Southern Ocean Site 690 An abyssal carbonate compensation depth overshoot in the aftermath of the Palaeocene–Eocene Thermal Maximum
منابع مشابه
Carbon dioxide forcing alone insufficient to explain Palaeocene--Eocene Thermal Maximum warming
The Palaeocene–Eocene Thermal Maximum (about 55 Myr ago) represents a possible analogue for the future and thus may provide insight into climate system sensitivity and feedbacks1,2. The key feature of this event is the release of a large mass of 13C-depleted carbon into the carbon reservoirs at the Earth’s surface, although the source remains an open issue3,4. Concurrently, global surface tempe...
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تاریخ انتشار 2016