Sedimentary environmental change induced from late Quaternary sea-level change in the Bonaparte Gulf, northwestern Australia

Takeshige Ishiwa,Yusuke Yokoyama,Minoru Ikehara,Yosuke Miyairi,Stephen Obrochta

doi:10.1186/s40562-016-0065-0

Takeshige Ishiwa, Yusuke Yokoyama + Show 3 more

Open Access

https://doi.org/10.1186/s40562-016-0065-0

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Abstract

Low-latitude continental shelves, mixed siliciclastic–carbonate sedimentary systems, provide an understanding of sedimentary environments driven by paleoclimatological processes. The Bonaparte Gulf, northwestern Australian continental shelf, is among the widest in the world, ranging to 500 km, with shallow carbonate terraces and platforms that were exposed during periods of lower sea level. The dominant sediments type switches between carbonate and siliciclastic over a sea-level cycle. However, the mechanism of sedimentary environmental change in the Bonaparte Gulf is not clearly understood. Here, we present a record of sedimentary environmental change from ca. 24 to 35 ka that is related to sea-level variability and exposure of carbonate terraces and platforms. Multi-proxy data from a marine sediment core show a sea-level change induced switch in sedimentary environment from siliciclastic to carbonate-dominated sedimentation during the last glaciation. Radiocarbon ages constrain the timing of this switch to ca. 26 ka, associated with a local sea-level fall of −90 m.

Highlights

Continental shelves are the main transport pathway of sediments from land to sea, playing an important role in the earth’s surface system
We describe the sedimentary consequences of past environmental change from a marine piston core (KH11-1-PC01) using Ca/Ti ratios, total organic carbon (TOC) and total nitrogen (TN), constrained by radiocarbon dating
Carbonate terraces and platforms and their deeply incised paleochannels play an important role in this paleoenvironmental change

Summary

Introduction

Continental shelves are the main transport pathway of sediments from land to sea, playing an important role in the earth’s surface system. The sedimentary environment of low-latitude mixed siliciclastic–carbonate continental shelves is strongly influenced by sea-level change and fluvial processes (Dunbar and Dickens 2003; Schlager et al 1994; Webster et al 2012). Detailed research on sedimentary environments of continental shelves improves our understanding of monsoonal intensity and sea-level variability (Bourget et al 2012; Yokoyama et al 2000). The Bonaparte Gulf, northwestern Australia, is a broad continental shelf with a water depth shallower than ~200 m (Bourget et al 2013, 2014). The area of the shelf has varied with relative sea-level change during the late Quaternary (Yokoyama et al 2001a).

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